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2020 Authors: Lu Gong, Ling Zhang, Li Xiang, Jiawen Zhang, Vahidoddin Fattahpour, Mahdi Mamoudi, Morteza Roostaei, Brent Fermaniuk, Jing-Li Luo, and Hongbo Zeng Surface interactions between emulsion drops and substrate surfaces play an important role in many phenomena in industrial processes, such as fouling issues in oil production. Investigating the interaction forces between the water-in-oil emulsion drops with interfacially adsorbed asphaltenes and various substrates is of fundamental and practical importance in understanding the fouling mechanisms and developing efficient antifouling strategies. In this work, the surface interactions between water drops with asphaltenes and Fe substrates with or without an electroless nickel–phosphorus (EN) coating in organic media have been directly quantified using the atomic force microscope drop probe technique. The effects of asphaltene concentration, organic solvent type, aging time, contact time, and loading force were investigated. The results demonstrated that the adhesion between water drops and the substrates was enhanced with higher asphaltene concentration, better organic solvent to asphaltenes, longer aging time, longer contact time, and stronger loading force, which was due to the growing amount and conformational change of asphaltenes adsorbed at the water/oil interface. Meanwhile, the adhesion between the water drop and the EN substrate was much weaker than that with the Fe substrate. The bulk fouling tests also showed that EN coating had a very good antifouling performance, which was in consistence with the force measurement results. Our work sheds light on the fundamental understanding of emulsion-related fouling mechanisms in the oil industry and provides useful information for developing new coatings with antifouling performances. Download paper
2020 Authors: Chong Sun, Jiankuan Li, Vahidoddin Fattahpour, Morteza Roostaei, Mahdi Mahmoudi, Hongbo Zeng, Jing-Li Luo The erosion-enhanced corrosion behavior of electroless Ni–P coating was investigated by single particle impingement coupled with in-situ electrochemical measurements. The transient anodic dissolution of Ni–P coating induced by the single particle impingement is enhanced with the rising impact velocity, followed by a rapid repassivation that obeys a bi-exponential decaying law. The coating demonstrates a good erosion-corrosion resistance due to its strong capability of repassivation that is scarcely affected by the changing hydrodynamics under the test conditions. The erosion-enhanced corrosion rate of Ni–P coating in flowing slurry is well predicted based on the repassivation kinetic parameters determined from single particle impingement. Download paper
2020 Authors: Zhengbin Wang, Chong Sun, Linlin Li, Morteza Roostaei, Vahidoddin Fattahpour, Mahdi Mahmoudi, Hongbo Zeng, Yugui Zheng, Jing-Li Luo Repassivation time (tre) is a significant parameter when evaluating the repassivation property of material. Herein, we propose a new method to obtain tre by first theoretically unifying the repassivation current–time (i(t)) function for common film growth models, subsequently simplifying the unified i(t) function based on single particle impingement data, then deriving the completed repassivation current expression corresponding to tre using mathematical approximation methods, and finally verifying this method via comparing the obtained tre of three materials. The newly proposed method is reliable, universal and simple to compare repassivation properties of different materials without curve fitting and considering film growth mechanism. Download paper
2020 Authors: Jiankuan Li; Chong Sun; Morteza Roostaei; Mahdi Mahmoudi; Vahidoddin Fattahpour; Hongbo Zeng; Jing-Li Luo The electrochemical corrosion behavior of Ni-P coating in 3.5 wt% NaCl solution-containing CO2 and H2S was investigated using electrochemical methods and surface characterization techniques. The results show that the presence of H2S can enhance the CO2 corrosion of Ni-P coated carbon steel by affecting both anodic and cathodic processes. The H2PO2 adsorbed layer only exists in the very early stage of corrosion and barely improves the anticorrosion performance of the coating. The formation of corrosion products (NiO and Ni3S2) renders temporary protection during immersion, but the addition of H2S accelerates the diffusion process at the electrolyte/coating interface and promotes the electrolyte penetration through the coating, causing severe localized corrosion and coating disbondment. A corrosion model is proposed to illustrate the corrosion and degradation process of Ni-P coated steel in the CO2/H2S/Cl− environment. Download paper
2020 Authors: Ali Habibi (University of Alberta) | Charles Fensky (Blue Spark Energy) | Mike Perri (Blue Spark Energy) | Morteza Roostaei (RGL Reservoir Management Inc.) | Vahidoddin Fattahpour (RGL Reservoir Management Inc.) | Mahdi Mahmoudi (RGL Reservoir Management Inc.) | Ali Ghalambor (Oil Center Research International) | Mohtada Sadrzadeh (University of Alberta) | Hongbo Zeng (University of Alberta)
Previous studies showed that different parameters influence the plugging of completion tools. These parameters include (i) rock mineralogy, (ii) reservoir fluids properties, and (iii) type of completion tools. Although different methods have been used for unplugging these tools, there is still debate regarding performance of these methods on damage removal.
In this study, we assessed the performance of high-power shockwaves generated from an electro-hydraulic stimulation (EHS) tool on cleaning completion tools plugged during oil production. These devices were extracted from different wells in Canada, Europe, and the US. First, we evaluated the extent of cleaning for the plugged completion tools using an EHS tool at the lab-scale. We examined the slots/screens before and after the treatment to show the performance of the EHS tool. Next, we analyzed the mineral composition and morphology of the plugging materials removed after the treatment by conducting X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray Spectroscopy (EDS) analyses. Finally, we reviewed the pulsing stimulation treatment results applied to several field case studies.
The results of unplugging sand control devices at the lab-scale showed that more than 50% of plugged slots/screens were cleaned after 45 pulses of shockwaves. The characterization results showed that the main plugging materials are calcite, silicate, and iron-based components (corrosion products). The results of field case studies showed an improved oil production rate after the pulsing stimulation treatment.
This paper provides a better understanding of the performance of shockwaves on damage removal from plugged completion tools. The results could provide a complementary tool for production engineers to select a proper method for treating the plugged tools.
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2020 Authors: Jiankuan Li, Chong Sun, Morteza Roostaei, Mahdi Mahmoudi, Vahidoddin Fattahpour, Hongbo Zeng, Jing-Li Luo
The electroless Ni-Mo-P/Ni-P composite coating was applied on N80 carbon steel, and the effects of Mo addition and heat treatment on the corrosion resistance enhancement in CO2/H2S/Cl− brine were studied by electrochemical measurements and surface analysis techniques. The Mo addition in the as-deposited Ni-P coating causes the microstructural transformation from amorphous to crystalline due to the reduced P content, thereby suffering severe corrosion. The impaired corrosion performance of as-deposited Mo-incorporated coating is also originated from the absence of the oxide film on the coating surface. Nonetheless, the heat-treated Ni-Mo-P/Ni-P coating exhibits desirable corrosion resistance, which is reflected by the outstanding corrosion inhibition efficiency (η = 96.1%). Heat treatment facilitates the formation of Ni4Mo phase and more importantly, the growth of an oxide film consisting of nickel and molybdenum oxides (H2S-immuned MoO3) with better passivation properties, which accounts for the remarkable corrosion resistance improvement.
2020 Authors: Ali Habibi (University of Alberta) | Charles Fensky (Blue Spark Energy) | Morteza Roostaei (RGL Reservoir Management Inc.) | Mahdi Mahmoudi (RGL Reservoir Management Inc.) | Vahidoddin Fattahpour (RGL Reservoir Management Inc.) | Hongbo Zeng (University of Alberta) | Mohtada Sadrzadeh (University of Alberta)
Scale deposition and its treatment are crucial part of any thermal recovery method. High temperature variation, phase change associated with steam condensation and flashing, and complex flow dynamics of the wells make the thermal wells more susceptible to scale deposition. Several studies evaluated the type of scales collected from plugged sand screens; however, more investigation is required to address the reservoir conditions and wellbore hydraulics affecting the scaling potential of minerals at downhole conditions.
A laboratory workflow combined with a predictive modeling toolbox to evaluate scaling tendency of minerals for different downhole conditions has been developed. First, saturation indices (SI) for different minerals were calculated at reservoir temperature and pressure using water chemistry analysis and the Pitzer theory. Then, the mineral composition of deposited materials collected from thermal wells in Athabasca and Cold Lake area were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectrometry (EDS), Total Organic Carbon (TOC) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analyses. Finally, a comparison analysis was performed between predictive and characterization results.
The results of SI calculations showed that Mg-based silicates and Fe-based minerals are positive (SI>5) even at high temperatures (T>430 K). This indicates that the possibility of deposition for these minerals is high. Carbonates (calcite and aragonite) minerals are the most common depositing minerals. However, the extent of scaling index of carbonates is controlled by the concentration of Ca, HCO3, and CO3 in the water sample. The characterization results confirm the results of modeling part. The results of SEM/EDS, ICP-MS analyses showed that carbonates, Mg-based silicates, and Fe-based corrosion products are the most common depositing materials among all minerals.
The workflow presented in this study will help the industry to evaluate the scaling potential for thermal wells at different downhole conditions to make a proper decision to prevent plugging of the completion tools.
Intelligent mineral segmentation in thin section images of rocks still remains a challenging task in modern computational mineralogy. The objective of the paper is segmenting minerals in geological thin section’s images with special attention on altered mineral segmentation. In this paper, an efficient incremental-dynamic clustering algorithm is developed for segmentation of minerals in thin sections containing altered and non-altered minerals. In the clustering algorithm, there is no need for determining the number of clusters (minerals) existed in thin section images, and also it is able to deal with color changing and non-evident boundaries in altered minerals. We have solved two main existing limitations: segmentation of mineral pixels that are frequently labeled as background pixels, and segmentation of thin sections containing altered minerals. Moreover, we created an open database (Alborz Mineralogical Database), as a benchmark database in computational geosciences regarding image studies of mineral. The proposed method is validated based on the results provided by the segmentation maps, and experimental results indicate that the proposed method is very efficient and outperforms previous segmentation methods for altered minerals in thin section images. The proposed method can be applied in mining engineering, rock mechanics engineering, geotechnique engineering, mineralogy, petrography, and applications such as NASA’s Mars Rover Explorations (MRE). Download paper
Particle size distributions (PSDs) plays an important role in designing sand control screens. Using different techniques (Dry Sieving, LPSA, and Dynamic Image Analysis (DIA)), large number of PSDs could be measured for core samples in a certain project. Moreover, large-scale sand retention tests are becoming common practice in recent years. These tests usually use duplicated sand mixtures of representative PSDs. Therefore, clustering the PSD data is essential for sand control design and sand retention tests. Supervised and unsupervised machine learning algorithms are getting more attention in computational petroleum engineering. Usually there is no clear idea that how many clusters are supposed to be detected in each PSD database. Therefore, due to the limitation for setting the number of clusters, PSD clustering could not be accomplished using conventional clustering algorithms such as k-means or artificial neural networks. As a new approach, PSD clustering based on an incremental clustering algorithm is used here. The proposed algorithm has online incremental learning capability and it is based on adaptive resonance theory (ART). Besides, the number of clusters is not needed to be assigned as an input parameter in the algorithm. The algorithm, based on a self-adaptation approach, tries to minimize the number of clusters. Accordingly, it is appropriate for PSD clustering of big databases. The proposed algorithm can be used in industrial applications such as sand control design and sand control evaluation testing. Download paper
Inflow Control Devices (ICDs) have been adopted for commercial steam-assisted gravity drainage (SAGD) production for nearly ten years and yet the function they serve is not well understood, and field data evaluating their performance remains scant. Thus, the purpose of the current study is twofold: Firstly, the study derives a simplified analytical model demonstrating how increasing the dP across ICDs acts to improve conformance along a producing lateral. The resulting equation of the analysis acts as a simple rule of thumb for determining an appropriate pressure drop across ICDs to achieve conformance. Secondly, the study evaluates the performance of ICDs that had been installed in four wells, two of which had ICDs installed prior to circulation and two that adopted ICDs later in their lifecycle. The field data shows that ICDs increase production rates and improve conformance along the lateral. These improvements are achieved by an increased drawdown facilitated by the ICDs. This part of the study highlights how early-life results may differ between ICD bearing wells compared to their conventionally completed (slotted liner) offsets: ICD bearing wells exhibit improved conformance and an ability to develop more challenging reservoir resulting in different oil production profiles and composite SORs. Download paper
Over the past few years, an increasing number of operators in steam assisted gravity drainage (SAGD) in situ recovery of bitumen in the Alberta Oil Sands are becoming interested in the use of flow control devices (FCDs). Initial field trials by some operators of these devices have shown promise in improving steam chamber conformance, reducing incidences of steam breakthrough, high vapour production, and in addressing liner reliability concerns related to steam jetting.
While the application of FCDs is well-established in the conventional oil and gas industry to control gas and water coning, there are still a number of questions on how to implement FCDs optimally in SAGD. One major difference in the application of FCDs in SAGD compared to the conventional oil and gas industry is the high temperature environment with steam and elevated erosion risk.
The purpose of this paper is to present some practical considerations for the selection of FCDs and optimal completion FCD design for SAGD applications. In the first section, a discussion is presented on how to compare the performance of different flow control devices. Most devices have not been tested for SAGD, and there is a need for more comprehensive testing. The focus of the second section is on practical considerations for the installation of FCDs in a SAGD injection and production wells.
Given the high viscosity of the oil, bitumen from oil sands reservoirs in western Canada is recovered by using steam which, due to its temperature, lowers its viscosity. One of the key issues faced by the operators is the steam conformance of the depletion chamber around wells. The greater the fingering phenomena of steam at the edge of chamber, the worse is the chamber uniformity and utilization of the well, and the greater are the green house gas emissions and water use per unit oil recovered. Fingering has long been explained as the penetration of steam phase into the oil phase which arises from an unfavourable mobility ratio. In this paper, we introduce linear instability analyses (Orr-Sommerfeld and Rayleigh-Taylor/Saffman-Taylor instability) of the interface between steam and oil layers and conduct a series of numerical simulations to reveal that fingering in the steam-assisted heavy oil recovery at the top of the steam chamber is created due to solution gas exsolution whereas fingering at the chamber edge is due to viscous shear instability. The results show that non-ideal steam conformance is inevitable even in homogeneous reservoirs.
Effective Steam Assisted Gravity Drainage (SAGD) operation relies on subcool management to reduce the risk of steam breakthrough. Monitoring of several parameters is performed to assure uniform development of steam chamber and heating of reservoir. This paper discusses the application of Distributed Acoustic Sensing (DAS), a monitoring platform to achieve reliable reservoir and wellbore surveillance in SAGD projects.
In this study, a comprehensive review of DAS deployment in oil and gas industry was performed including vertical seismic profiling, hydraulic fracturing, well/pipe integrity and flow profiling applications. Then, SAGD flow monitoring was investigated in detail. To utilize DAS in SAGD projects, knowing completion designs are necessary. Therefore, various SAGD completion designs and corresponding flow regimes were discussed as well. Finally, four flow loop designs were proposed to accurately simulate the complex wellbore hydraulics of the SAGD producer using DAS recordings.
This work started with an overview of DAS systems in downhole monitoring including real time high resolution vertical seismic profiling, hydraulic fracturing characterization and optimization, well and pipe integrity, leak detection and assessing completion effectiveness. Then, flow profiling including flow rate, flow fractions and flow regimes determinations using DAS were discussed with focus on SAGD monitoring. Completion designs directly impact on SAGD monitoring and DAS recordings, more specifically on flow regimes inside the tubing and annulus. Therefore, various completion designs with their tubing and screen sizes were presented and corresponding flow regimes were determined in both tubing and annulus. It was observed that flow regimes vary with type of completion design, liquid flow rate, steam breakthrough locations and tubing/screen sizes. Eventually, four flow loop designs were proposed based on the discussions for future DAS application.
This paper discusses existing completion designs and possible flow regimes in SAGD projects. Consequently, novel designed flow loops are introduced for DAS deployment to better understand the complex wellbore hydraulic of the well and measure the key parameters in optimizing the production operation. This study is a design stage for future quantitative measuring of flow profiling using DAS systems.
Accurate prediction of flow regime and flow profile in wellbore is among the main interests of production engineers in the quest of optimizing wellbore production and increasing reliability of downhole completion tools especially in SAGD projects. This study introduces a methodology for wellbore monitoring by detecting flow phase and flow regime. In order to develop this method, an advanced multi-phase flow injection experiment was designed and commissioned.
A flow injection setup was developed to test distributed fiber optic sensor installation under different operating conditions, including multi-phase flow (oil, brine and gas), and flow fraction scenarios. Different signal processing methods were applied to extract meaningful features and filter the noise from the raw signals. A statistical analysis was performed to assess the trend of the driven data. Then, typical SAGD models were simulated to assess the results of experimental setup for scale-up purpose and determination of local breakthrough of steam along the well.
Results showed that the Distributed Acoustic Sensing (DAS) data contains different levels of signals for each phase and flow regime. We also found that some level of uncertainties is involved in relating the flow regime and DAS information which could be resolved by improving the sensor installation procedure. In addition, the application of data-driven machine learning methods was found necessary to interpret the signal patterns. Initial results have shown that steam breakthrough along the well can be detected using real time DAS high energy/frequency signals. It can be concluded that including the DAS along with Distributed Temperature Sensing (DTS) is necessary to provide a better picture of steam conformance and SAGD wellbore monitoring. The limitations of the current experimental setup restricted further conclusions regarding the hybrid DAS and DTS application.
This paper is a part of an ongoing project to address the application of the combined DAS and DTS in SAGD projects. The ultimate goal is a downhole monitoring system to oversee the flow phase, flow regime and sand ingress in thermal application. The next phase will address the required improvements for developing a flow loop to handle high temperatures, include sand production and mimic thermal operation conditions.
Studies that investigate and attempt to model the process of steam-assisted gravity drainage (SAGD) for heavy-oil extraction often adopt the single-phase-flow assumption or relative permeability of the moving phases as a continuous phase in their analyses. Looking at the emulsification process and the likelihood of its prevalence in SAGD, however, indicates that it forms an important part of the entire physics of the process. To explore the validity of this assumption, a review of prior publications that are related to the SAGD process and the modeling approaches used, as well as works that studied the emulsification process at reservoir conditions, is presented. Reservoir conditions are assessed to identify whether the effect of the emulsion is strong enough to encourage using a multiphase instead of a single-phase assumption for the modeling of the process. The effect of operating conditions on the stability of emulsions in the formation is discussed. The review also covers the nature and extent of effects from emulsions on the flow mechanics through pore spaces and other flow passages that result from the well completion and downhole tubing, such as sand/flow-control devices. The primary outcome of this review strengthens the idea that a multiphase-flow scenario needs to be considered when studying all flow-related phenomena in enhanced-oil-recovery processes and, hence, in SAGD. The presence of emulsions significantly affects the bulk properties of the porous media, such as relative permeability, and properties that are related to the flow, such as viscosity, density, and ultimately pressure drop. It is asserted that the flow of emulsions strongly contributed to the transport of fines that might cause plugging of either the pore space or the screen on the sand-control device. The qualitative description of these influences and their extents found from the review of this large area of research is expected to guide activities during the conception stages of research questions and other investigations.
The interactions of the bubbles in a loosely packed bubbly flow in a high viscous fluid approaching a pore space are studied using a shadowgraph imaging technique. The motion of the bubbles has been evaluated by considering shape analysis of their deformation and the variation in the velocity and pressure distribution of the phase. A comparison of two cases of a linear array and a matrix of bubbles emphasizes the importance of the arrangement on the deformation and motion of the dispersed phase in the pore space. The deformation of the bubbles in both cases results in a deceleration and acceleration process of the dispersed phase in the pore region. This process was a function of size, number of the bubbles competing in the pore throat and the arrangement of the competing bubbles. The variation in the motion of the dispersed phase will ultimately lead to different flow motion and phenomena at the entrance of the pore throat. The results also highlight that although bubbles had different motion approaching the pore throat, they follow similar deformation transition as they enter and exit the pore throat. This work contributes to existing knowledge of multi-phase flow in pore space by providing further understanding the effect of the interaction of phases based on the arrangement and their motion in a porous geometry.
An in-situ measurement technique to determine the rheology of a fluid based on the experimentally measured velocity profile of a flow in a mini-channel is introduced. The velocity profiles of a Newtonian and different shear-thinning fluids along a rectangular channel were measured using shadowgraph particle image velocimetry (PIV). Deionized water and different concentrations of a polyacrylamide solution were used as Newtonian and shear-thinning fluids, respectively and were studied at different Reynolds numbers. The flow indices of the fluids were determined by comparing the experimental velocity profile measurements with developed theory that takes into account the non-Newtonian nature of the fluids rheology. The results indicated that the non-Newtonian behavior of the shear-thinning fluid intensified at lower Reynolds numbers and it behaved more as a Newtonian fluid as the Reynolds number increased. A comparison between the power law index determined from experimental monitoring of the velocity profile at different Reynolds numbers and measurements from a rheometer reflected good agreement. The results from the study validate the new approach of the rheology measurement of Newtonian and non-Newtonian flows through straight, rectangular cross-section channels. The proposed approach can be further utilized using other methods such as X-ray PIV to characterize the rheology of non-transparent fluids and in general, for all non-Newtonian fluids.
The flow of dispersed gas bubbles in a viscous liquid can create a bubbly, slug bubble, or elongated bubble flow regime. A slug bubble flow, characterized by bubble sizes equal to the hydraulic diameter of the channel, is a transition regime with a complex local flow field that has received little attention in the past. In this study, dynamics of this flow regime in a square capillary with a cross-sectional area of 3 × 3 mm² was studied analytically and experimentally. The main geometric parameters of the flow field, such as film and corner thicknesses and volume fraction, were calculated for different flow conditions based on a semi-empirical approach. Using velocity fields from particle image velocimetry (PIV), combined with the analytical equations derived, local mean variations of the film and corner flow thicknesses and velocity were analyzed in detail. Analysis of the results reveals a linear relation between the bubble speed and the liquid slug velocity that was obtained using sum-of-correlation PIV. Local backflow, where the liquid locally flows in the reverse direction, was demonstrated to occur in the slug bubble flow, and the theoretical analysis showed that it can be characterized based on the bubble cross-sectional area and ratio of the liquid slug and bubble speed. The backflow phenomenon is only contributed to the channel corners, where the speed of liquid can increase to the bubble speed. However, there is no evidence of reverse flow in the liquid film for the flow conditions analyzed in this study.
Wire-wrapped screens (WWSs) are one of the most-commonly used devices by steam-assisted gravity drainage (SAGD) operators because of the capacity to control plugging and improve flow performance. WWSs offer high open-to-flow area (OFA) (6 to 18%) that allow a high release of fines, hence, less pore plugging and accumulation at the near-screen zone. Over the years, several criteria have been proposed for the selection of aperture sizes on the basis of different industrial contexts and laboratory experiments. Generally, existing aperture-sizing recommendations include only a single point of the particle-size distribution (PSD). Operators and academics rely on sand-control testing to evaluate the performance of sand-control devices (SCDs). Scaled laboratory testing provides a straightforward tool to understand the role of flow rate, flowing phases, fluid properties, stresses, and screen specifications on sand retention and flow impairment.
This study employs large-scale prepacked sand-retention tests (SRTs) to experimentally assess the performance of WWSs under variable single-phase and multiphase conditions. The experimental results and parametric trends are used to formulate a set of empirical equations that describe the response of the WWS. Several PSD classes with various fines content and particle size are tested to evaluate a broad range of PSDs. Operational procedures include the coinjection of gas, brine, and oil to emulate aggressive conditions during steam-breakthrough events.
The experimental investigation leads to the formulation of predictive correlations. Additional PSDs were prepared to verify the adequacy of the proposed equations. The results show that sanding modes are both flow-rate and flowing-phase dependent. Moreover, the severity or intensity of producing sand is greatly influenced by the ratio of grain size to aperture size and the ability to form stable bridges. During gas and multiphase flow, a dramatic amount of sanding was observed for wider apertures caused by high multiphase flow velocities. However, liquid stages displayed less-intense transient behaviors. Remarkably, WWSs rendered an excellent flow performance even for low-quality sands and narrow apertures. Although further and more complete testing is required, empirical correlations showed good agreement with experimental results.
This paper focuses on the study of proppant transport mechanisms in fractures during frac-packing operation. A multi-module, numerical proppant, reservoir and geomechanics simulator has been developed, which improves the current numerical modeling techniques for proppant transport. The modules are linked together and tailored to capture the processes and mechanisms that are significant in frac-pack operations. The proposed approach takes advantage of a robust and sophisticated numerical smeared fracture simulator and incorporates an in-house proppant transport module to calculate propped fracture dimensions and concentration distribution. In the development of software capability, the propped fracture geometry and proppant concentration, which are the output of the proppant module, are imported to the hydraulic fracture simulator through mobility modification. Complex issues of proppant transport in fractures that are addressed in the literature and captured by the current model are: hindered settling velocity (terminal velocity of proppant in the injection fluid), the effect of fracture walls, proppant concentration and inertia on settling (due to extra drag forces applied on particles, compared to single-particle motion in Stokes regime in unbounded medium), possible propped fracture porosity and also mobility change due to the presence of proppant, and fracture closure or extension during proppant injection. A sensitivity analysis is conducted using realistic parameters to provide guidelines that allow more accurate predictions of the proppant concentration and fluid flow. The main objective of this study is to link a numerical hydraulic fracture model to a proppant transport model to study the fracturing response and proppant distribution and to investigate the effect of proppant injection on fracture propagation and fracture dimensions. Download paper
Slotted liners have been widely used in steam-assisted gravity drainage (SAGD) wells owing to their low cost and superior mechanical integrity. Multiple factors affect the performance of slotted liners, such as particle size distribution (PSD) of formation sands, aperture size, slot density, fluid flow rate, and wellbore operational conditions. Currently, most of the existing design criteria formulate the lower and upper bounds of the aperture based on one or several points on the particle size distribution curve of oil sands. Most of these design criteria neglect the slot density, wellbore operational conditions, and shape of PSD curve.
This study carries out a series of large-scale pre-pack sand retention tests (SRT) in step rates. The aim is to investigate the impacts of aperture size, slot density, and fluid flow rate on the slotted liner performance. Comprehensive design criteria for determining the safe aperture window are presented to maintain the sanding and the wellbore plugging of the zone near the slotted liners within an acceptable level. Sand production governs the upper bound of the aperture size, and flow performance guides the lower bound of the aperture size. The new criteria are presented graphically to illustrate the optimal slot window as a function of the sand PSD, slot density, and fluid flow rate. The results of separate tests are used to demonstrate the performance of the new design criteria. The optimal slot window obtained via the new design criteria guides the slot liner selection in the SAGD process. Download paper
Final proppant distribution inside hydraulic fractures which depends on particle properties, movement and deposition highly impact wellbore productivity and consequently is crucial in modeling and design of hydraulic fracturing. This paper presents a thorough review of laboratory scale tests performed on proppant transport related to hydraulic fracturing treatments and governing physics behind its mechanisms.
The interaction between fluid (gas and liquid) and solid particles has been investigated in applied mathematics and physics. In such phenomena, there is always a relative motion between particles and fluids. In this work this relative motion during proppant movement, sedimentation and fluidization in both small- and large-scale lab tests have been assessed in detail. Existing correlations which relate proppant particles settling velocity to concentration of proppant particles, fracture wall and inertia effect in Newtonian and non- Newtonian fluid are presented as well.
Lab tests show that various parameters determine the proppant particles distribution inside the fractures. Particle settling velocity, an influential parameter in this regard, is impacted by fracture walls, inertia and the presence of other particles. Inertia changes the relation of drag coefficient and Reynold number. Fracture wall and particles concentration decrease settling velocity as drag force increases. At a certain level, concentration reaches to its limit. Proppant concentration, in addition, increases the suspension viscosity, fracture width and net pressure. However, it deceases the fracture length as more pressure loss occurs along the fracture. As a result, well productivity is highly impacted by the proppant settling and distribution.
Many studies have been devoted to identifying different aspects of hydraulic fracturing and proppant transport mechanisms in porous media. This study highlights the key parameters and their effects, existing correlations and physics behind them for better understanding and management of this mechanism. Download paper
A large-scale sand retention test (SRT) facility is used to investigate the flow performance of SAS. Duplicated sand samples with similar particle size distribution (PSD), shape, and mineralogy properties to the McMurray Formation oil sands are obtained by mixing different types of commercial sands, silts, and clays. Oil and brine are simultaneously injected into the sand-pack at different water-cut levels and liquid rates to emulate the changing inflow conditions in SAGD operations. The saturation levels in each flow stage are measured to determine the relative permeability values. Next, the relative permeability curves of the duplicated sand-pack sample are measured following the steady-state method. Finally, the pressure data obtained from the SRT in each flow stage are coupled with the relative permeability values to calculate the retained permeability as the indicator of flow performance of SAS'.
Generally, testing results show that single-phase oil flow generates minor and negligible permeability impairments in the near-screen zone of the sand-pack. An evident permeability reduction is observed once the water breakthrough happens, indicating that the wetting-phase fluid significantly mobilizes fine particles and causes pore plugging. Also, with the increase of flow rate and water cut, a further reduction in permeability is found as a result of the higher drag force and greater exposure area of fines to brine.
The proposed methodology presented in this study allows quantitative characterization of the formation damage under multi-phase flow condition and provides a practical and straightforward method for the evaluation of the SAS's flow performance.
Sieve analysis, sedimentation and laser diffraction have been the methods of choice in determining particle size distribution (PSD) for sand control design. However, these methods do not provide any information regarding the particle shape. In this study, we introduce the application of Dynamic Image Analysis (DIA) to characterize particle sizes and shape descriptors of sand bearing formations.
Dynamic Image Analysis, an advanced method of particle size and shape characterization, along with other PSD measurement methods, including sieving combined with sedimentation, and laser diffraction, was utilized to study size and shape variations of 372 unconsolidated formation sand samples from North America, Latin America, and the Middle East. Different methods were compared for the estimation of PSD and fines content, which is important for sand control design.
Through minimizing the sampling and measurement errors, the deviation between different PSD measurement techniques was attributed solely to the shape of the particles and the amount of fine fraction. For fines content measurement, the values obtained through Feret Min. parameter values (the minimum size of a particle along all directions) calculated by DIA and sieving measurement are comparable within a 5% confidence band. The deviation between the results of different methods becomes more significant by increasing fines content. Moreover, this deviation increases for less isodiametric grains. The fines and clay content show higher values when measured by any wet analysis. Laser diffraction also tends to overestimate the fines fraction and underestimate silt/sand fraction compared to other dry techniques. By comparing the deviation of the DIA and sieving at standard mesh sizes, an algorithm has been developed which chooses the equivalent sphere sizes of DIA with minimum deviation from sieving.
This study performs several measurements on formation sands to illustrate the real advantage of the new methods over traditional measurement techniques. Furthermore, particle shape descriptors were used to explain the deviation between the results of different PSD measurement methods.
Standalone screens (SAS) have been widely employed as the main sand control solution in thermal projects in Western Canada. Most of the test protocols developed to evaluate screen designs were based on the scaled screen coupons. There have been discussions regarding the reliability of such tests on scaled coupons. This paper presents the results of the tests on full-scale wire-wrapped screen (WWS) and slotted liner coupons for typical McMurray Formation sands.
A large-scale sand control evaluation apparatus has been designed and built to accommodate all common SAS with 3 1/2″ in diameter and 12″ in height. The set-up provides the capability to have the radial measurement of the pressure across the sand pack and liner, for three-phase flow. We outline certain challenges in conducting full-scale testing such as establishing uniform radial flow and measuring the differential pressure. Produced sand is also measured during the test. The main outputs of the test are to assess the sand control performance and the mode of sanding in different flow direction, flow rates and flow regimes.
We were able to establish uniform radial flow in both high and low permeability sand packs. However, the establishment of the radial flow in sand packs with very high permeability was extremely challenging. The pressure measurement in different points in radial direction around the liner indicated a uniform radial flow. Results of the tests on a representative PSD from McMurray Formation on the WWS and slotted liner coupons with commonly used specs in the industry have shown similar sanding and flow performances. We also included aperture sizes smaller and larger than the common practice. Similar to the previous large-scale tests, narrower apertures are proven to be less resistant to plugging than wider slots for both WWS and slotted liner. Accumulation of the fines close to screen causes significant pore plugging, when conservative aperture sizes were used for both WWS and slotted liner. On the other hand, using the coupon with larger aperture size than the industry practice, resulted in excessive sanding. The experiments under linear flow seems more conservative as their results show higher produced sand and lower retained permeability, in comparison to the full scaled testing under radial flow.
This work discusses the significance, procedure, challenges and early results of full-scale physical modeling of SAS in thermal operation. It also provides an insight into the fluid flow, fines migration, clogging and bridging in the vicinity of sand screens.
Kazakhstan owns one of the largest global oil reserves (~3%). This paper aims at investigating the challenges and potentials for production from weakly-consolidated and unconsolidated oil sandstone reserves in Kazakhstan.
We used the published information in the literature, especially those including comparative studies between Kazakhstan and North America. Weakly consolidated and unconsolidated oil reserves, in Kazakhstan, were studied in terms of the depth, pay-zone thickness, viscosity, particle size distribution, clay content, porosity, permeability, gas cap, bottom water, mineralogy, solution gas, oil saturation, and homogeneity of the pay zone. The previous and current experiences in developing these reserves were outlined. The stress condition was also discussed. Furthermore, geological condition, including the existing structures, layers and formations were addressed for different reserves.
Weakly consolidated heavy oil reserves in shallow depths (less than 500 m) with oil viscosity around 500 cP and thin pay zones (less than 10 m) have been successfully produced using cold methods, however, thicker zones could be produced using thermal options. Sand management is the main challenge in cold operations, while sand control is the main challenge in thermal operations. Tectonic history is more critical in comparison to the similar cases in North America. The complicated tectonic history, necessitates the geomechanical models to strategize the sand control especially in cased and perforated completion. These models are usually avoided in North America due to the less problematic conditions. Further investigation has shown that Inflow Control Devices (ICDs) could be utilized to limit the water breakthrough, as water coning is a common problem, which initiates and intensifies the sanding.
This paper provides a review on challenges and potentials for sand control and sand management in heavy oil reserves of Kazakhstan, which could be used as a guideline for service companies and operators. This paper could be also used as an initial step for further investigations regarding the sand control and sand management in Kazakhstan.
Designing/Selecting the proper sand control mechanism for horizontal wells in unconsolidated heavy-oil reservoirs tend to be under-looked in some cases. Stand-alone completions pose some sand control challenges, which could jeopardize the oil production or even lead to critical problems. Massive sand production, screen/formation plugging, formation of velocity hot-spots and mechanical integrity failures are some of the well-known issues. This study attempts to optimize the sand control design for horizontal wells in a heavy-oil field in Colombia.
A careful selection of representative core data was made to study the variation of sand Particle Size Distribution (PSD) within the development area. Reservoir fluid properties were analyzed. Based on PSD variation and current design criteria in the industry, several seamed slotted-liner configurations were proposed as an alternative completion for testing. Later, a series of large-scale Sand Retention Tests (SRTs) were performed to assess the selected alternatives under typical field production conditions. Effects of aperture size and open to flow area (OFA) were investigated to evaluate flow and sand control performance.
This investigation started by a detailed study of the PSD, particle shape variation and composition of fines in the development area. The PSDs were then classified into four distinct minor and major sand facies, ranging from medium to very coarse sand with different fines content. Further investigations have shown that current design is only suitable for a limited number of PSDs, while the overall PSD classes indicate requirement of wider slot aperture sizes. The results of the SRTs indicated that the flow performance of the screen is mainly controlled by the slot aperture. Choosing the optimized aperture size avoids unacceptable sanding even for the multiphase flow scenarios with gas. Results also indicated that by increasing the aperture size and application of the seamed slots for the studied formation, plugging could be mitigated. Finally, a detailed Finite Element Analysis (FEA) was conducted to compare the mechanical integrity of the current slotted liner design and the optimized design obtained from the experimental testing.
A comprehensive sand control design workflow for cold primary heavy oil production in horizontal wells is presented in this work. The current study is one of the first that investigates and compares conventional straight slotted liners with seamed slotted liners at larger scale for a field. Moreover, this study helps to better understand the effect of design parameters of seamed slotted liners on sand control, flow performance and mechanical strength.
Most of the test protocols developed to evaluate sand-screen designs were based on scaled-screen test coupons. There have been discussions regarding the reliability of such tests on scaled test coupons. This paper presents the results of tests on wire-wrapped screen (WWS) and slotted liner (SL) test coupons for typical onshore Canada McMurray formation sand.
A unique sand control evaluation apparatus has been designed and built to accommodate all common stand-alone screens that are 3.5 in. in diameter and 12 in. in height. This setup provides the capability to have a radial measurement of pressure across the sandpack and screen for three-phase flow. Certain challenges during testing such as establishing uniform radial flow and measuring the differential pressure are outlined. Produced sand is also measured during the test. The main outputs of the test are to assess the sand control performance and the mode of sanding in different flow directions, flow rates, and flow regimes.
It was possible to establish uniform radial flow in both high- and low-permeability sandpacks. However, the establishment of radial flow in sandpacks with very high permeability was challenging. The pressure measurement at different points in the radial direction around the screen indicated a uniform radial flow. Results of the tests on a representative particle size distribution (PSD) from the McMurray Formation on the WWS and SL test coupons with commonly used specifications in the industry (aperture sizes of 0.012, 0.014, and 0.016 in. for WWS and 0.012, 0.016, 0.018, and 0.020 in. for SL) have shown similar sanding and flow performances. We also included aperture sizes smaller and larger than the common practice. Similar to previous tests, narrower apertures are proven to be less resistant to plugging than wider slots for both WWS and SL. Accumulation of fines close to the screen causes significant pore plugging when conservative aperture sizes were used for both WWS and SL. In contrast, using the test coupon with a larger aperture size than the industry practice resulted in excessive sanding. The experiments under linear flow seem more conservative because their results show more produced sand and smaller retained permeability in comparison to the testing under radial flow.
This work discusses the significance, procedure, challenges, and early results of physical modeling of stand-alone screens in thermal operation. It also provides insight into the fluid flow, fines migration, clogging, and bridging in the vicinity of sand screens.
Erosion of standalone screens in thermal wells can lead to significant damage and reduction in production. The dominant failure mechanism is the development of localized high-velocity hot spots in the screen due to steam breakthrough or flashing of the steam across the screen. This study provides methods to assess the erosion potential of screen material devices to determine the allowable production conditions which avoid erosion.
In this study the effects of impact angle, flow rate, sand concentration, particle size, and fluid viscosity on erosion are systematically investigated through a multivariable study. Experimental impingement testing is performed on screens in different orientations. Erosion is accessed by collecting weight loss data of the screen. Empirical erosion models are calibrated to provide predictions of functional relationships between erosion rate and varied parameters. Computational Fluid Dynamic (CFD) simulations are performed prior to the experimental work to visualize particle flow paths through the screen and determine local flow and impact velocities and wear patterns.
The performance of five existing erosion models is assessed through experimental testing of sand control screens. In order to translate short-term, high-velocity laboratory test results into field erosion predictions, an empirical erosion model is then developed and employed to provide well flow guidelines and minimize erosion potential. This suggests that the use of erosion prediction models in situations in which due to lack of time/data tuning is not possible, may still provide a reasonable estimate for the rate of material loss of the screen. The model is used to obtain threshold superficial velocity curves for several conditions.
The main concern associated with existing erosion models is that they do not consider sand production, nor do they account for many other factors that affect erosion process. An erosion model, coupled with CFD simulation, has been developed, that account for factors such as geometry, size, material, fluid properties and rate, sand size, shape, and density in downhole flow conditions.
Primary Cold Heavy Oil Production with Sand (CHOPS) recovery factors are low (typically 8%) and most of the oil is left behind in the formation. Canadian Natural Resources Limited (Canadian Natural) is pursuing alternatives to primary recovery and secondary post CHOPS Enhanced Oil Recovery (EOR) to recover more of this stranded oil resource. Wire-wrapped screens were investigated, using a High-Pressure High Temperature Sand Retention Testing (HPHT-SRT) apparatus, for sand control and inflow performance in a CHOPS formation near Bonnyville, Alberta.
A new HPHT-SRT apparatus was designed/commissioned to better understand the role of oil viscosity on the capability of the standalone sand control screen. The facility allows to control the temperature of the fluid flowing across the sand pack and sand control coupon at different pressure drops. Each test is performed at constant pressure drops up to 300 psi. The temperatures up to 85 °C were tested. Coupons of wire-wrapped screen with three aperture sizes (0.008″, 0.010″, and 0.012″) were tested. Canadian Natural provided oil sand cores and crude oil from the target formation for this testing.
The results indicated a high dependency of the near screen flow performance on the temperature and oil viscosity. As the increase in temperature reduces the oil viscosity below 300 cP, the near screen pressure gradient falls 26% to 40% under constant pressure drop for different aperture sizes. As the screen aperture increases from 0.008″ to 0.012″, the flow rate increases up to 20% for the test stages at 85°C temperature and up to 162% for the test stages at 25°C, for the tested pressure drops. The results indicate that at higher viscosities, the aperture size is the dominant factor in screen flow performance where a slight increase in aperture increases the flow performance and reduces pressure drop. However, increasing the aperture size, up to 0.012″, led to an increase in the sanding over 0.20 lb per square feet of the screen (lb/sq.ft.), which exceeds the acceptable threshold of 0.12 to 0.15 lb/sq.ft. for typical SRTs. Based on the pressure drops and produced sand results, a 0.010″ aperture size was recommended for the target formation.
This paper outlines the results of the experiments with a HPHT-SRT, which is developed to better assess the function of sand control design for heavy oil assets. This phase of the work mainly focused on better understanding the role of the oil viscosity on sand control performance.
The historical challenges and high failure rate of using standalone screen in cased and perforated wellbores pushed several operators to consider cased hole gravel packing or frac-packing as the completion of the choice. Despite the reliability of these options, they are more expensive than standalone screen completion. Since several developments are not designed for cased hole gravel pack or frac-pack, purpose-driven sand control methods for cased and perforated wells are recommended.
This paper employs a combined physical lab testing and Computational Fluid Dynamics (CFD) for lab scale and field scale to assess the potential use of the standalone screen in completing the cased and perforated wells. The aim is to design a fit-to-purpose sand control method in cased and perforated wells and provide guidelines in perforation strategy and investigate screen and perforation characteristics. More specifically, the simultaneous effect of screen and perforation parameters, near wellbore conditions on pressure distribution and pressure drop are investigated in detail.
A common mistake in completion operation is to separately focus on the design of the screen based on the reservoir sand print and design of the perforation. If sand control deemed to be required, the perforation strategy and design must go hand in hand with sand control design. Several experiments and simulation models were designed to better understand the role of perforation density, the fill-up of annular gap between the casing and screen, perforation collapse and screen plugging on pressure drop. The experiments consisted of a series of step rate tests to investigate the role of fluid rate on pressure drop and sand production. There is a critical rate in which the sand filled annular gap will fluidize and also sanding would be different for different fluid density. Both test results and CFD simulation scenarios comparatively allow to establish the relation between wellbore pressure drop with screen and perforation parameters and determine the optimized design.
The results of this study highlight the workflow to optimize the standalone screen design for the application in cased and perforated completion. The proper design of standalone screen and perforation parameters allows maintaining cost-effective well productivity. Results of this work could be used for choosing the proper sand control and perforation strategy, rather than using gravel packing and frac-packing methods in cased and perforated completions.
A smeared fracture type hydraulic fracture simulator is developed through numerical coupling between an in-house reservoir simulator and a geomechanical commercial software (FLAC2D). The new package falls within the category of partially decoupled model and is versatile, flexible and efficient. This approach can be used to couple any other advanced commercial fluid flow or geomechanical simulators for an accurate description of the initiation and propagation of hydraulic fractures.
The paper contains a discussion of the partial coupling technique to link fluid flow and geomechanical calculations in modeling fracture initiation and propagation. The models use a common gridblock for the fracture and reservoir and use the deformation calculations to update the porosity and permeability. The method captures the interactive effects of the fracture on reservoir fluid flow and formation geomechanics through stress dependent permeability and porosity.
The developed smeared fracture model can capture both tensile and shear fractures in the formation. Major features of this model include modeling poroelasticity and plasticity, matrix flow, shear and tensile fracturing with concomitant permeability enhancement, saturation-dependent permeability, stress-dependent stiffness and gradual degradation of oil sands due to dilatant shear deformation. The model has been applied to numerically simulate field size hydraulic fracturing in oil sands during cold-water injection to show the predictive capability of the simulator.
Designing and selecting the proper sand control mechanism for horizontal wells in unconsolidated heavy-oil reservoirs tend to be underlooked in some cases. Standalone completions pose some sand control challenges, which could jeopardize the oil production or even lead to critical problems. Massive sand production, screen/formation plugging, hot spots, and mechanical integrity failures are some of the well-known issues. This study attempts to optimize the slotted liner design for horizontal wells in a heavy-oil field in Colombia.
A careful selection of representative core data was made to study the variation of sand particle-size distribution (PSD) within the development area. Reservoir fluid properties were analyzed. Based on PSD variation and current design criteria in the industry, several seamed slotted-liner configurations were proposed as an alternative completion for testing. Later, a series of large-scale sand retention tests (SRTs) were performed to assess the selected alternatives under typical field production conditions. The effects of aperture size and open-to-flow area were investigated to evaluate flow and sand control performance.
This investigation started with a detailed study of the PSD, particle shape variation, and composition of fines in the development area. The PSD then classified into four distinct minor and major sand facies, ranging from medium to very coarse sand with different fines content. Further investigations have shown that current design is only suitable for a limited number of the PSDs, while the overall PSD classes indicate the requirement for wider slot aperture sizes. The results of the SRTs indicated that the flow performance of the screen is mainly controlled by the slot aperture. Choosing the optimized aperture size avoids unacceptable sanding even for the multiphase flow scenarios with gas. Results also indicated that by increasing the aperture size and application of the seamed slots for the studied formation, plugging could be mitigated.
A comprehensive sand control design workflow for cold primary heavy-oil production in horizontal wells is presented in this work. The current study is one of the first that investigates and compares conventional straight slotted liners with seamed slotted liners at a larger scale for this field. Moreover, this study helps to better understand the effect of design parameters of seamed slotted liners on sand control, flow performance, and plugging tendency.
A large-scale pre-packed Sand Retention Tests (SRT) facility was employed to simulate SAGD well conditions. Brine with different NaCl salt concentrations was injected into synthetic sand-pack samples that are representative of the McMurray Formation. Flow rates were varied during the test, and fines migration along the sand-pack was traced. Differential pressures along the sand pack were recorded to calculate the permeability changes during the test. Samples of produced water were collected immediately below the coupon to measure the fines concentration. Testing parameters such as pH, clay mineralogy, temperature, and sand control specifications were kept constant in all tests.
Fines concentration in the produced water during the test and retained permeability were considered as the indicators of the fines migration inside the sand-pack. Results of step-rate testing display a jump in fines concentration in produced water right after each flow rate increase. Besides, fines concentration results show that fines migration was insignificant when using brine with high salt concentrations. Fines migration was stronger for a relatively narrow salinity range with low NaCl concentrations, resulting in the highest pore plugging. The findings in this research are consistent with past studies which relate clay dispersion to the zeta potential of clay materials: the higher the zeta potential, the stronger the fines dispersion and migration.
Based on this study, it is recommended that the operating companies monitor the chemical properties of the produced water. Field operators could preserve the reservoir productivity by manipulating the formation salinities to lower the dispersion and detachment of fines and their migration towards the production well.
The presence of both transverse and axial hydraulic fractures can cause significant near-wellbore tortuosity. Besides, the stress distribution around the perforation tunnel has a substantial impact on the fracture initiation pressure and thus the fracture geometry near the wellbore. The introduced analytical model was verified against existing models. The model has been successfully applied to different conditions of in-situ stress and wellbore orientations, which were not addressed in previous studies. The results can be used to obtain the optimum well and perforation design in deviated wellbores by providing the minimum fracture initiation pressure and the perforation orientation that minimizes the near-wellbore fracture tortuosity.
The standard cut point test was used to determine the micron rating of different meshes in order to categorize them in different classes based on the average pore size. Different mesh weaves, namely Dutch twill, reversed Dutch twill and square mesh screens with different micron rating were investigated in terms of filtration performance. In the next step, a dead-end filtration set-up was designed and commissioned to evaluate the flow performance and sand control capabilities of mesh screens. Additionally, a new, customized sand control device was designed and included in the testing matrix to compare its performance with the common mesh screens in the market.
Dead-end filtration results indicated that by choosing the proper combination of morphology, both optimized open to flow area (OFA) and sand control could be achieved. The custom designed hybrid screen performed better compared to other investigated mesh screens with similar micron rating, in terms of both flow and filtration performance. Therefore, the customization was found to be the key parameter to achieve the optimized design. This further emphasizes that by employing the hybrid benefits of surface size exclusion and depth filtration, one can reach the optimized sand control and flow performance. Regarding the weave of different mesh screens, the results did not show any trends that could lead to a conclusion of better performance of a certain weave. Further investigations are required under different testing condition to achieve a conclusive comparison between different mesh types.
This paper investigates the possibility of customized sand control design, which uses the hybrid benefits of surface size exclusion and depth filtration to reach the optimized sand control and flow performance.
A large-scale SRT facility was developed to investigate the performance of the gravel pack in two-phase flow regime. The testing set-up allows for co-injection of oil and brine at controlled flow rate and water cut level to emulate different scenarios for two-phase flow across the gravel pack and sand screen/liner. Testing measurements included produced sand, absolute pressures, and differential pressure drops across the slotted liner, gravel pack, gravel-sand pack interface and sand pack. The test procedure and test matrix were designed to enable an accurate assessment of the gravel pack and slotted liner performance for different fluid flow scenarios. Rolled-top and straight-cut slotted liner coupons were used for this study.
Test results showed negligible sand production for both rolled-top and straight-cut slotted liners, however the produced sand was slightly higher for the rolled-top profile. The pressure drop across the rolled-top liners were smaller than the straight-cut liners based on the analytical analysis presented in this study. The results have also shown that a key factor in gravel packing performance is the ratio of the gravel pack size to the formation sand (sand pack) size. Larger gravels allow an easier production of the fines, while smaller gravels may trap the fines and be plugged over time.
This work provides a robust testing facility to address the gravel pack performance in steam-drive producer wells. The results help the engineers with gravel pack and sand control design and an evaluation for the entire wellbore life.
A large-scale Sand Retention Test (SRT) was used to investigate the role of steam breakthrough in the sand control performance. Produced sand and pressure drops along the sand-pack were the main measurements during the tests. The test procedure and test matrix were designed to enable the examination of the impact of steam breakthrough on sand production for different steam rates.
Two possible sanding mechanisms are postulated in steam breakthrough events: (1) local grain disturbance caused by the high-velocity steam near the liner, (2) effect of the complex phase behavior of the steam and the subcool level. Two different testing procedures were designed to examine these mechanisms. The local grain disturbance mechanism was investigated by injecting air at a wide range of velocities. Results indicate that this mechanism could not lead to a significant sanding when there is a bit of effective stress near the liner. Hence, it looks like that the steam velocity poses a higher risk in early stages of SAGD production when the near-liner stress is very low. The effect of high-pressure high-temperature (HPHT), low- to high-quality steam flow and the subcool level will be investigated in the next phase of the study. This work addresses the effect of high-quality steam breakthrough on the sand control performance of the liner in SAGD producer wells. The findings in this paper help the researchers to direct their research to better understand the steam breakthrough. This research will eventually help the engineers in their liner design and evaluation for the entire wellbore life cycle as the near-well stress evolves.
In addition to a critical review of existing sand control testing approaches for SAGD, the paper also discusses the testing parameters in previous studies to evaluate their representativeness of the field conditions in terms of interstitial seepage and viscous forces, and flow geometry. Moreover, the paper reviews the analysis and results of sand control testing in the literature and assesses the sand control design criteria in terms of the level of acceptable sand production and plugging. Furthermore, the review evaluates the suitability of the sample size, sand preparation techniques, representation of the SCD in the testing, and experimental procedures.
The review shows variations in the existing sand control testing in SAGD, in terms of not only approach, sand control representation, and sample size, but also regarding operational test conditions, such as flow rates and pressures. Ideally, large-scale pre-packed tests that include the effects of temperature and radial flow geometry would more closely emulate the actual conditions of SAGD wells than most existing tests allow. High temperatures may affect sanding and plugging through changes in wettability, permeabilities, and mineral alterations. Further, the varying velocity profile in radial flow towards the SCD influences the fines migration pattern differently from the linear-flow conditions in the existing Sand Retention Tests (SRT). However, large-scale radial-flow tests are constrained by cost and complexity.
Most SRT experiments have employed high flow rates, exceeding the equivalent field rates. Utilizing realistic rates for the tests and appropriately capturing the actual fluids ratios, water cuts and steam breakthrough scenarios can improve the quality of testing data. Accordingly, existing SRT experiments can be designed to incorporate, if not all, but some of the relevant physics in SAGD by employing representative viscosities, flow rates, fluid properties and ratios, stress conditions and obtain suitable live and post-mortem measurements.
This critical review compiles various aspects of current sand retention tests and evaluates their applicability to SAGD well conditions. It serves as a starting point for future research by providing an overview of existing testing methods, highlighting the strengths and opportunities for improvements.
A large-scale sand retention testing facility was developed and employed to conduct a series of tests on slotted liner coupons with different slot widths and densities. These tests were tailored to simulate steam injection and backflow during the shut-in. Three representative particle size distributions for the McMurray Formation were used in this study ranging from coarse to fine sand. The experimental set-up allows to measure the amount of produced sand.
Since the produced sand in steam injection wells is not usually cleaned out, the acceptable threshold for sand production in the injector should be more conservative than the same for producer wells. Testing results indicate that the sand control performance of the liner is governed by the slot width and density, and formation particle size distribution. Results indicate a negligible amount of produced sand with gas backflow for a properly designed liner even at very high gas velocities.
Historically, there has been little attention to the sand control design for injector wells. This work highlights the significance of slot density and slot width in the sand control performance for steam injection wells. The paper provides the basis for the proper design of an effective sand control in SAGD injectors.
The study collected a large databank of PSDs from published SPE papers and historical drilling reports. These data indicate significant variations in the PSD for different reservoirs and geographical areas. The literature review identified more than 30 mathematical equations that have been developed and used to represent the PSD curves. Different statistical comparators, namely, adjusted R-squared, Akaike's Information Criterion (AIC), Geometric Mean Error Ratio, and Adjusted Root Mean Square Error were used to evaluate the match between the measured PSD data with the calculated PSD from the formulae. The curve fit performance of the equations for the overall data set as well as PSD measurement techniques were studied. A particular attention was paid towards investigating the effect of fines content on the match quality for the calculated versus measured curves.
It was found that certain equations are better suited for the PSD database used in this investigation. In particular, Modified Logestic Growth, Fredlund, Sigmoid and Weibull models show the best performance for a larger number of cases (highest adjusted R-squared, lowest Sum of Squared of Errors predictions (SSE), and very low AIC). Some of the models show superior performance for limited number of PSDs. Additionally, the performance of PSD parameterized models is affected by soil texture: For higher fines content, the performance of equations tends to deteriorate. Moreover, it appears the PSD measurement techenique can influence the performance of the equations. Since the majority of the PSD resources used here did not mention their method of measurement, the effect of measurement technique could only be tested for a limited data, which indicates the measurement technique may impact the match quality.
Fitting of parameterized models to measured PSD curves, although well known in sedimentology and soil sciences, is a relatively unexplored area in petroleum applications. Mathematical representation of the PSD curve improves the accuracy of D-values determination, hence, the sand control design. This mathematical representation could result in a more scientific classification of the PSDs for sand control design and sand control testing purposes.
This paper presents a new large-scale sand retention testing (SRT) facility to simulate the effect of pressure pulsation and backflow in injection wells on the sand control performance of SAS. The SRT facility can be used in the selection of the best sand control method for injector wells. It can be also used to provide further understanding on the impact of formation damage on well injectivity decline, as well as study the effect of water hammer pressure pulsation on sand production in injection wells.
Test results show a rapid fall off in the pressure and drastically high backflow rates due to the sudden shut-in. Higher pressure drops are observed to result in a greater backflow volume and a longer backflow period. Results also show that the slot width has a drastic influence on the sanding performance of the screen. Testing observations, for the studied PSD, indicate that the injection well requires narrower slots 1.4 D10 to meet the sand production requirements due to a high fluidization potential in the near-screen zone. Higher flow velocities during the backflow period and the tossing effect caused by the pressure waves increase the sanding potential. The produced sand during the backflow period, is observed to mainly relate to the ratio of the slot width to the mean formation grain size. It is observed that higher effective stresses around the screen work towards stabilizing the sand bridges and reducing the amount of produced sand.
This paper presents a new experimental test facility for the sand control type selection and evaluation for injection wells with the aim of limiting the amount of produced sand and sustaining the wellbore injectivity. The proposed testing facility allows the performance comparison of different sand control devices and designs.
A Scaled Completion Testing (SCT) facility was utilized to emulate multi-axial stress and multiphase flow conditions near the sand control liner. Brine, oil, and gas were used as flowing fluids. Sand-pack samples were prepared using commercial sands by matching the particle size, shape and, composition of the McMurray Formation oil sands. A constant lateral stress and several axial stresses were applied to simulate the stress conditions around the liner. The three-phase flow condition was used to evaluate the role of the steam breakthrough on the liner performance.
Experimental results indicate the critical role of stress conditions around the liner on its sanding and plugging responses. Results show gradual sand-pack compaction with the gradual increase of the axial stress. Higher axial stresses result in a smaller amount of produced sand, which can be attributed to the stronger inter-particle frictional resistance, hence, stronger and more stable sand bridges behind the slots. The higher compaction results in a lower porosity and permeability, hence, altering the plugging and sanding response of the liner. Also, higher retained permeabilities are found for stronger anisotropic stress conditions. Besides, it is found that the three-phase flow condition could cause a stronger fines migration and production, compared to single-phase flow.
The results of this study indicate that the stress and multiphase flow effects are crucial factors in the evaluation of slotted liner performance. The findings from the innovative experimental studies provide insights into the practicability of evaluating slotted liner performance with the consideration of sophisticated field conditions and optimizing the selection of the slotted liner aperture for the entire well lifespan.
Slotted liners have been extensively used as a sand control device in SAGD wells. Slotted liners must allow free flow through the slots with minimal plugging and acceptable amounts of sand production.
In our study, large-scale unconsolidated sand was packed over a multi-slot coupon of the slotted liner. The sand-pack was subjected to several stress conditions corresponding to the evolving stress conditions during the life cycle of a SAGD producer well. The testing program employed several multi-slot coupons to examine the flow performance under typical encountered stresses in SAGD wells. Cumulative produced sand was measured at the end of testing as an indicator of the sand control performance. The permeability evolution of the sand in the near-coupon zone was calculated by measurements of pressure differentials and considered as a measure of screen flow performance. Fines/clay concentration along the sand-pack was also quantified after the test to investigate the fines migration, a phenomenon which is considered to be the main reason for reduced wellbore productivity.
Experimental results show that the liner performance is significantly affected by the normal stress buildup on the liner. Experimental observations indicate sand-pack compaction due to the increase of effective stress around the liner leads to a lower porosity and permeability. The situation near the liner is further complicated by the fines accumulation that results in pore plugging and further permeability reduction. When it comes to sanding, however, higher stresses help stabilize the sand bridges behind the slots, leading to less sand production.
As for the design criteria, the lower and upper bounds of the slot size are governed by plugging and sand production, respectively. Considering the stress effect on plugging and sanding, testing data indicate that both the lower and upper bounds should be revised to larger slot aperture sizes.
Different reservoir geological settings and long horizontal wells impose limitations and operational challenges on the implementation of SAGD technology. Wellbore trajectory excursions or undulations- unintentionally generated trajectory deviations due to suboptimal drilling operations- are some of the complications that lead to non-uniform steam chamber conformance, high cumulative Steam-Oil Ratio (cSOR) and low bitumen recovery.
Conventional dual-string completion scheme (a short tubing landed at the heel, and a long tubing landed at the toe) has been widely adopted in most of the SAGD operations. Such configurations allow steam injection at two points: the toe and the heel sections of the horizontal well. However, these completions have demonstrated poor efficiency when reservoir/well complications exist. Tubing-deployed Flow Control Devices (FCD's) have been introduced to offer high flexibility in delivering specific amounts of steam to designated areas (such as low permeability zones) and ensure uniform development of steam chamber in the reservoir. The work in this thesis presents the results of a numerical effort for optimizing the design of Outflow Control Devices (OCD's) in SAGD wells for different scenarios of well pair trajectory excursions.
A coupled wellbore-reservoir SAGD simulation model was constructed to optimize the placement and number of ports in every single OCD. Three different cases were generated from the constructed basic SAGD model with each case having a specific well pair trajectory which causes variable lateral distances between the well pair.
Results of the optimized OCD's cases demonstrate a higher SAGD efficiency compared to their corresponding conventional dual-string cases. Those enhancements resulted in a higher steam chamber conformance, a higher cumulative oil production, and an improved Net Present Value (NPV).
The finite volume analysis evaluates the skin factor as a result of pressure drop in the gap between the casing wall and the slotted liner. This skin model accounts for: 1) the perforation density and phasing, 2) slotted liner specifications, and 3) different amount of sand accumulation in the annular space between the casing and the sand screen. A semi-analytical pressure drop model is also linked to the numerical model to incorporate the skin factor due to flow convergence behind the perforations.
The results of finite volume analysis reveal that a low perforation density would behave close to the open-hole completion for sand-free casing-liner annular space. Conversely, pressure drops were found to be significant for a partially or totally filled space. Additionally, it was found that the optimum completion design occurs if the slotted liner joints are in line with the casing joints. Besides, a partially perforated casing or a partially open sand screen increases the distance fluids have to travel in the annular space and intensifies the skin factor.
This paper provides skin models derived for vertical and perforated wells completed with slotted liner sand screens using the finite volume simulations. Each part of the model has been verified against existing numerical models in the literature. The model improves the understanding of flow performance of the sand screens and skin factor, which in turn leads to a better design of sand control completions.
In this research, a series of Sand Retention Tests (SRT) was conducted, and results were used to formulate a set of design criteria for slotted liners. The proposed criteria specify both the slot width and density for different operational conditions and different classes of Particle Size Distribution (PSD) for the McMurray oil sands. The goal is to provide a qualitative rationale for choosing the best liner design that keeps the produced sand and skin within an acceptable level. The test is performed at several flow rates to account for different operational conditions for Steam Assisted Gravity Drainage (SAGD) and Cyclic Steam Stimulation (CSS) wells. A Traffic Light System (TLS) is adopted for presenting the design criteria in which the red and green colors are used to indicate, respectively, unacceptable and acceptable design concerning sanding and plugging. Yellow color in the TLS is also used to indicate marginal design.
Testing results indicate the liner performance is affected by the near-wellbore flow velocities, geochemical composition of the produced water, PSD of the formation sand and fines content, and composition of formation clays. For low near-wellbore velocities and typical produced water composition, conservatively designed narrow slots show a similar performance compared to somewhat wider slots. However, high fluid flow velocities or unfavorable water composition results in excessive plugging of the pore space near the screen leading to significant pressure drops for narrow slots. The new design criteria suggest at low flow rates, slot widths up to three and half times of the mean grain size will result in minimal sand production. At elevated flow rates, however, this range shrinks to somewhere between one and a half to three times the mean grain size.
This paper presents novel design criteria for slotted liners using the results of multi-slot coupons in SRT testing, which is deemed to be more realistic compared to the single-slot coupon experiments in the previous tests. The new design criteria consider not only certain points on the PSD curve (e.g., D50 or D70) but also the shape of the PSD curve, water cut, and gas oil ratio and other parameters.
The study employs a large pre-packed SRT to assess the performance of WWS with different aperture sizes and standard wire geometries. The testing plan includes sand samples with two representative particle size distributions (PSD's) and fines contents. Testing procedures were designed to capture typical field flow rates, water cut, and steam-breakthrough scenarios. The amount of sand production and pressure drop across the zone of the screen and adjacent sand were measured and used to assess the screen performance. Furthermore, fines production was measured to evaluate plugging tendencies and flow impairment during production.
The experimental results and data analysis show that aperture selection of WWS is dominated by their sand retention ability rather than the flow performance. The relatively high open flow area (OFA) makes WWS less prone to plugging. There is an increase in flow impairment after finalizing the injection scheme (oil+water+gas); however, it is controlled over the acceptable margins even with a narrow aperture. Further, a comparison of initial and final turbidity measurements showed that fines mobilization and production during single-phase brine flow was higher than in two-phase brine-oil flow at the same liquid flow rate. Excessive produced sand was observed for wider slots during the multi-phase (brine, oil, and gas) flow when gas was present, highlighting the impact of the breakthrough of wet steam on sand control performance. Flow impairment and pressure drop evolution were strongly related to the mobilization and accumulation of fines particles in the area close to the screen coupon; it is critical to allow the discharge of fines to maintain a high-retained permeability. Results also signify the importance of adopting adequate flow rates and production scenarios in the testing since variable water cuts and GORs showed to impact both sanding and flow performances.
This research incorporates both single-phase and multiphase flow testing to improve design criteria for wire-wrapped screens and provide an insight into their performance in thermal recovery projects. An improved post-mortem analysis includes fines production measurements to correlate these to the retained permeability caused by the pore plugging, which has hardly been evaluated in previous studies.
Several failed standalone screens have been studied, which were collected from various fields and operational conditions. The screens were first inspected visually, and then certain sections of screens/pipes were selected for more detailed study on the failure mechanism. The liners/screens were cut into sections to be studied through SEM-EDX, reflective light microscopy, X-ray micro CT scan and petrographic thin sections to better understand the localized plugging mechanism. Through the studies of several polished sections, a statistical variation of the plugging zone was found. Moreover, we further focused on the critical zones such as the inlet and outlet of the aperture and the zone adjacent to the formation to better investigate the plugging mechanism.
The study on wire wrap screen samples revealed significant plugging of the annular space between the base pipe and the screen. Extensive clay/fines buildup in the annular space led to full to partial clogging in some sections. The base pipe corrosion study reveals that the corrosion mechanism is highly flow dependent since the perforation on the base pipe was enlarged to an oval shape from the original circular shape with its larger axis pointing toward the flow direction. The size of the plugged zone was significantly higher in the outer diameter section where a mixture of the clay and corrosion byproducts plugged the near screen pore space and the screen aperture. Examined premium mesh screen samples showed that the plugging mechanism is highly sensitive to the mesh size and assembly process. The highest pore impairments were associated with mesh screens in which the mesh was directly wrapped around the base pipe causing a reduced annular gap for the flow toward the perforations. The investigation of slotted liner samples showed widest plugging zone in the slot entrance and the lowest on the slot wall. A distinct interplay of the clay and corrosion byproduct led to the adsorption of clay, forming a compacted layer over the slot wall.
This paper reviews the plugging mechanism of the standalone sand control screen obtained from the field to provide first-hand evidence of the plugging mechanism and provides explanations for some of the poor field performances. The results could help engineers to better understand the micro-scale mechanisms leading to sand control plugging.
A large-scale wellbore simulator was developed to study the performance of the tubing deployed scab liner screen as remedial sand control, where the sand entry point, the concentration and PSD of the sand in addition to the flow rate and the ratio of different phases could be controlled precisely. Two-phase flow of oil and brine along with sand could be injected through different ports along the clear pipe, emulating the slurry flow entering into the wellbore. Clear pipe allows visualization of the sand transport and sand accumulation above the tubing deployed scab liner during the fluid injection. An experimental study of the performance of Wire Wrap Screen (WWS) with different aperture sizes is presented in this paper.
Results indicated the requirement of a different approach for designing the correct aperture size for remedial scab liners since using the current design sand control criteria leads to large amount of solid production. It seems that the design of aperture size for scab liners should be more toward the lower bound in comparison with the common screen designs in thermal applications. The sand entry point distance from the tubing deployed scab liner screen position was found to be the critical parameter in the sanding and flow performance of the remedial sand control. Fluid flow in the annulus causes the segregation of sand grains; finer grains are carried with fluid, while coarser grains settle closer to the injection ports. The slurry flow regime in the annulus results in continuous sand production until a stable bridge and later a stable sand bed is formed on top of the tubing deployed scab liner screen. Moreover, results showed that the main pressure drop happens across the nozzles on the tubing, while the pressure drop across the accumulated sand pack in the annulus and coupon was less significant.
This paper introduces an experimental tool for evaluating the tubing deployed scab liner performance as remedial sand control in thermal applications. The developed experimental testing and facility could help to better design and evaluate the remedial tubing deployed scab liner sand control solutions.
The proposed analytical skin factor model for slotted liners is based on slot width, slot density, the spatial distribution of slots, and near-liner permeability. The model also incorporates partial plugging of slots. The model is validated using experimental Sand Retention Testing (SRT) data. A series of SRT experiments were conducted at different flow rates for two Particle Size Distributions (PSD) from the McMurray Formation in Northern Alberta. The experiments were also modeled by the CFD to better understand the flow dynamic near the liner.
Results of the analytical model and experimental tests were generally in agreement. However, results of the analytical model deviate from experimental tests for narrow slots and high flow rates. In these cases, the analytical model predicts smaller skin than the experimental tests. For cases related to narrow slots and higher velocity the pore plugging close to the liner is significant which was not modeled in the analytical model. Moreover, for very fine sand (low permeability) sand-pack the deviation from the experimental results is higher in comparison with medium uniform sand (higher permeability) sand-pack. CFD simulations showed the effect of the slot width on the depth of the convergence zone, which is not included in the analytical model. Since the analytical model follows the experimental results for common flow rates in thermal production, the model could be used to assess the skin for different possible designs and choose the best slot specifications that minimize the skin.
This paper presents the details of an analytical model for the skin factor verified by experimental data and CFD simulation. This analytical model can be used to optimize the liner specification for the best flow performance. This paper also outlines the limitations of the analytical models for calculation the skin/pressure drop.
This paper is based on the analysis of 152 PSD curves for Alberta oil sands. To categorize these PSD's in a meaningful way, an algorithmic approach is presented which uses attributes that are widely used in sand control design (e.g. D10, D50, D70, fines content) and, subsequently screens and sorts the data to produce a finite number of PSD categories which represent the majority of the data. Rules are implemented in the algorithm to limit the number of categories (≤7), and require that each category cover a significant subset of the total data (≥10%).
A review of the published PSDs for oil sands across Alberta indicates a significant variation in the PSD curves even within the same reservoir. However, in spite of the fact that PSD data show a large variation, PSD categories can be identified to build representative oil sand samples for design and testing purposes. For the database used in this investigation, four major and two minor PSD classes were identified. These six PSD classes, cover more than 87% of the analyzed PSDs. Introduced classes and existing PSD classifications in the literature share interesting similarities. However, certain differences, such as the lack of very coarse ranges (D50~500 µm) was observed.
The method which is introduced for oil sand classification is based on the D-values which are commonly used in screen aperture design. This method provides a useful tool for both screen designers and researchers to categorize and focus their work on a specific set of representative PSDs, rather than a wide distribution of PSDs.
We set up a large-scale Sand Retention Testing (SRT) facility that accommodates a multi-slot liner coupon at the base of a sand-pack with representative grain shape and particle size distribution (PSD) of typical oil sands. Brine is injected at different flow rates and pressure differences across the coupon and the sand-pack as well as the mass and PSD of the produced sand and fines are measured during the test. Further, the PSD and concentration of migrated fines (<44 microns) along the sand-pack are determined in a post-mortem analysis. The testing results are used to assess the effect of slot size and slot density on the sand control performance as well as pore-plugging and permeability alterations near the sand-control liner.
We observed that the slot size, slot density and flow rate highly affect the concentration and PSD of produced fines as well as accumulated fines (pore clogging) above the screen. For the same flow rates and total injected pore volume, wider screen aperture and higher slot density result in lower fines accumulation above the screen but more sanding. Further, the variation of slot density alters the flow convergence behind the slots, hence, the size and concentration of mobilized fines. Results indicate that higher fines concentration near the screen reduces the retained permeability, hence, lowers the wellbore productivity.
This paper provides a new insight into pore plugging and fines migration adjacent the sand control liner. It also introduces a new testing method to optimize the design of sand control liners for minimum productivity impairment in SAGD projects.
The SRT facility was commissioned to improve the existing testing methods by (1) using multiple-slot rather than single-slot coupons, (2) using more realistic sand pack preparation/saturation procedures than the existing practices, (3) measuring the pressure drop along the sand pack and across the liner coupon to assess the retained permeability and flow convergence, and (4) post-mortem analysis of the sand pack to measure fines/clay content along the sand pack as a direct measure of fines migration. Several tests were performed by varying the slot size, slot density, and PSD of the sand pack, and flow rate. The testing data were used to validate and improve the current industrial design of slotted liners.
Test measurements and observations indicate that the sand pack preparation procedure highly affects the testing results. For typical field porosities and PSDs, we observed finite amount of sand production bellow the existing criteria for sanding during the SRT, for the screens designed based on existing models. Testing data also indicate smaller retained permeability for lower slot density due to converging flow. Moreover, measurements indicate lower retained permeability for narrower slot width, caused by the accumulation of fines and pore plugging in the liner's vicinity. However, larger slot width than a certain size contributes to higher levels of sanding. Three different sanding modes are identified: (1) initial sanding or sand occurrence, (2) flow rate dependent transient and (3) flow rate dependent continuous sanding. It is proposed that the sanding mode should be also included in the design criteria along with the acceptable sanding threshold. Test results indicate the combined effect of the slot size and density on both retained permeability and sand production. These findings lead to a new design approach for maximum retained permeability and acceptable sand retention.
This paper introduces a new set of design criteria for slotted liners based on the results of a novel large-scale testing to evaluate the sand control for thermal heavy oil production applications. Also it provides a better understanding of the sand production and the role of the slot width and slot density on the sand production. The paper also presents an improved understanding of the sanding and permeability evolution close to the liner in relation to several liners and flow parameters. The set-up, testing procedures, and measurement methods that are used in the experiments improve the existing methods in several fronts.
This study builds on existing experimental procedures and investigates fines migration, sand production and clogging tendency of slotted liner coupons in large-scale unconsolidated sand-packs. Sand-packs with controlled properties (grain size distribution, grain shape, and mineralogy) are packed on a multi-slot sand control coupon in a triaxial cell assembly. Varying levels of stress are applied to the sand-packs in directions parallel and perpendicular to the multi-slot coupon. For each stress level, brine is injected into the sand-pack from the top surface of the sample towards the coupon. Test measurements include pressure drops across the sand-pack and the coupon as well as the produced sand/fines mass for each stress level. Post-mortem analysis is performed to measure fines/clay concentration along the sand-pack as a direct measure of fines migration.
Experimental results show that under the subsequent increase in effective stresses, sand-packs experience considerable deformations in directions parallel and perpendicular to the multi-slot coupon; which result in a drastic drop in the porosity and retained permeability. Test results show that the maximum reduction in permeability occurs in the vicinity of the multi-slot coupons due to the fines accumulation and the higher compaction in that region. In comparison to experiments with no confining stress, the application of confining stress results in lower retained permeability in the sand-packs as well as reduced sand production.
This paper presents, for the first time, the effect of near wellbore effective stress on clogging tendency and sand retention characteristics of slotted liner completions. The tests allow the assessment of the adequacy of the use of existing design criteria over the life cycle of the well under variable stress conditions around the liner.
Twenty-three oil sands samples were collected from two wells in the McMurray Formation and cleaned using the Soxhlet extraction technique. The cleaned samples were examined using the image analysis technique and Scanning Electron Microscope (SEM) imaging to study their Particle Size Distribution (PSD), shape factors, mineralogy, and texture. Similar analysis was performed on eleven series of commercial sands to compare their shape, mineralogy, and texture with those of oil sands. Particle Size Distribution of 10 commercial fines was also analyzed with a particle sizer to cover the required fine/clay part of the duplicated samples. Direct shear and 1D consolidation were performed to compare the mechanical properties of the oil sands samples and the duplicated mixtures of commercial sands and fines.
The shape factors of the oil sand and the selected commercial sand samples are in close agreement. In addition to the common average/cumulative shape factor measurements, this paper also presents the variation of shape factors within each sample for different grain sizes. The results show the same sand shape characteristics among all oil sand samples as well as the tested commercial sands. Further, XRD results indicate a similar mineralogy for the commercial sands and the oil sands samples. The SEM images show random changes in the surface texture of both oil sands and commercial sands with no observable trends. We were able to use commercial sands and fines mixture with similar grain shape properties to duplicate the PSD of the oil sand samples. Direct shear and 1D consolidation testing of the oil sands and samples made of commercial sands and fines show similar consolidation and frictional properties for both the duplicated mixture and cleaned oil sands for the same compaction level (porosities).
This paper provides a procedure for duplicating the oil sands with commercial sands and fines. It also provides detailed information on the mineralogy, texture, and the variation of the shape characteristics for oil sands from the McMurray Formation.
Water with different pH, in the range of 6.8 to 8.8, and salinities, in the range of 0 to 1.4 % was injected into sand pack samples supported with multi-slot coupon in a Sand Retention Testing (SRT) facility. Measurements included pressure drops along the sand pack and across the slotted liner coupon as well as the produced sand/fines for different flow rates. These measurements were used to assess the effect of the pH and salinity on fines migration within the sand pack, capability of the slotted liner to produce the fines, pore and slot plugging, sand production and the retained permeability.
We observed that the pressure drops, fines production and the retained permeability are highly dependent on the pH and salinity of the injected fluid. In low pH and high salinity environment, clay is not mobilized resulting in low pressure drops and high retained permeabilities. On the other hand, an increase in pH value or a decrease in salinity leads to significant clay mobilization and a remarkable reduction in retained permeability.
This paper provides a thorough experimental investigation of the pH and salinity effect on slotted liner performance. The effect of the pH and salinity is usually ignored in screen control testing while it could highly control the clay mobilization and retained permeability. Results of this study could trigger wide reconsideration in sand control approaches particularly by altering the pH in the near wellbore zone.
In this paper we present the results of a comprehensive image analysis and laser sieve analysis on oil sand samples from the McMurray Formation to quantify geometrical grain characteristics (sphericity, aspect ratio, convexity and angularity) of the sand grains and establish the PSD of the samples. Direct shear tests were performed to assess the frictional characteristics of different oil sands around the liner under variable stress conditions during the SAGD well lifecycle.
Image analysis, PSD, and direct shear tests showed that natural mixture of oil sand could be successfully simulated with commercial sands in terms of size and shape of grains and mechanical properties. This conclusion is significant to those performing large-scale sand control evaluation tests that usually require large quantities of sands that are not readily available and require significant preparation.
This paper provides the first comprehensive investigation of the granular, and geomechanical characteristics of oil sand from the McMurray Formation. The paper discusses the missing parameters in the design of sand control device, and evaluates test methods that measure those parameters. The proposed testing program could be used as a benchmark for oil sand characterization in relation to the design and evaluation of sand control device.
In steam injection thermal recovery, it is essential to have a uniform flow to improve the recovery and to avoid the localized steam breakthrough which could lead to damage to well completion. In this paper, we propose three quantitative criteria to assess the performance of inflow control devices (ICD) based on computational fluid dynamics (CFD) modeling. The new performance criteria are exemplified in the evaluation of a few basic ICD designs.
To evaluate the response of the ICD to flow rate and fluid type, three new performance criteria, defined as (1) quadratic flow coefficient, (2) viscosity coefficient, and (3) erosion potential, are proposed and evaluated based on a set of CFD simulations. The first criterion measures the flow rate response and the ability of the ICD to restrict high velocity flow, the second quantifies the viscosity sensitivity, and the third predicts the potential for erosion in the device.
Four different liner deployed ICD designs, based on two passive design types (nozzle and channel) and one autonomous design type (Tesla flow diode), were analyzed using a rigorous CFD model. The model includes the surrounding slotted liner and inner tubing to identify any interactions of the ICD with the surrounding completion. The CFD model has been verified for grid and domain independence and it was applied to a range of flow rates representative of the field condition. In addition, simulations were run for a range of single-phase incompressible fluids with varying viscosities.
Using the newly proposed criteria, the ICDs were evaluated and compared. The comparison shows that, of these devices, the diode does the best job of restricting the flow at high flow speeds and low viscosities. At high viscosities, such as in the case of oil, the diode is the least restrictive device. Although the two straight nozzles tested are slightly worse at restricting the flow, they have the lowest erosion potential. Based on this comparison and the proposed criteria, the channel design performs poorly. At low viscosities it does not sufficiently restrict the flow, and at high viscosities it overly restricts the production of oil. It also has a high erosion potential, because of the steep entrance angle.
In this work, a new set of quantifiable criteria are defined and assessed that allow multiple aspects of different ICD designs to be compared simultaneously. Overall, these three criteria give a highly sensitive, quantitative means of comparing ICD designs. With these three criteria together, a more comprehensive comparison can be made in support of selection and improvement of ICDs.
The bubble formation frequency from a single-orifice nozzle subjected to the effects of a crossflowing liquid was investigated using high-speed shadowgraphy, combined with image analysis and signal processing techniques. The effects of the nozzle dimensions, orientation within the conduit, liquid cross-flow velocity, and gas mass flow rate were evaluated. Water and air were the working fluids. Existing expressions in the literature were compared to the experimental values obtained. The expressions showed modest agreement with the experimental mean average frequency magnitude. It was found that increasing the gas injection diameter could decrease the bubbling frequency approximately 12% until reaching a certain value (0.52 mm). Further increasing the nozzle dimensions increase the frequency by around 20%. Bubbling frequency is more sensitive to the liquid velocity where changes up to 63% occurred when the velocity was raised from 3.1 to 4.3 m/s. Increasing gas mass flow rates decreased the gas jet breakup frequency in all cases. This phenomenon was primarily attributed to changes in the bubbling mode from discrete bubbling to pulsating and jetting modes. The nozzle orientation plays a role in modifying the bubbling frequency, having a higher magnitude when oriented against gravity.
Computational fluid dynamics has been extensively used for fluid flow simulation and thus guiding the flow control device design. However, computational fluid dynamics simulation requires explicit geometry input and complicated solver setup, which is a barrier in case of the cyclic computer-aided design/computational fluid dynamics integrated design process. Tedious human interventions are inevitable to make up the gap. To fix this issue, this work proposed a theoretical framework where the computational fluid dynamics solver setup can be intelligently assisted by the simulation intent capture. Two feature concepts, the fluid physics feature and the dynamic physics feature, have been defined to support the simulation intent capture. A prototype has been developed for the computer-aided design/computational fluid dynamics integrated design implementation without the need of human intervention, where the design intent and computational fluid dynamics simulation intent are associated seamlessly. An outflow control device used in the steam-assisted gravity drainage process is studied using this prototype, and the target performance of the device is effectively optimized.
Multi-view feature modelling provides a specific view for each phase in product development. The analysis view should be fully integrated with CAD models in a multi-view product development environment for simulation-based design. In the development of fluid flow products, CFD (Computational Fluid Dynamics) is increasingly used as an advanced support. However, the successful application of CFD requires special knowledge and rich experience, which is a barrier for the conversion from the design view to the analysis view, and the maintenance of information consistency. Several approaches to multiple feature views have been proposed, such as design by features, feature recognition and feature conversion. In one-way feature conversion, features in a specific view are usually derived from the original design view. Bronsvoort and Noort put forward a multiple-way approach which enables a designer to modify the product model from an arbitrary view. In this paper, the CAE interface protocol is used to convert the features in the design view into the CAE boundary features [5] in the analysis view. Based on the physical knowledge, an expert system is established to further process those features and generate a robust simulation model with the help of fluid physics features and dynamic physics features in the analysis view.
One of the main methods of extracting oil from deep oil sands deposits is through the use of steam assisted gravity drainage (SAGD). For the best performance, inflow control devices (ICDs) are implemented along the SAGD production well to even out production and restrict unwanted fluids. Current methods of evaluating these devices rely on criteria that are dependent on the flow rate and fluid properties at which they are measured. In this study, three new criteria are proposed to evaluate and compare ICDs. These new criteria are derived from the physics of the flow in order to tie them to specific aspects of the flow and to have a reduced dependence on the flow rate and fluid properties. To further reduce the dependence of the criteria, they are calculated from a range of data, using a least squares fit. In order to evaluate the proposed criteria, detailed CFD models are developed for six fundamental ICD designs: a 15◦ nozzle, a 40◦ nozzle, a long channel, an expanding nozzle, a device based on Tesla’s fluidic diode, and a vortex based device. The CFD models are carefully tested to ensure they accurately model the flow. Using these simulations, the three criteria are calculated for each device. The criteria are then compared to the flow results and examined for flow and viscosity independence. Finally, the criteria are used to compare the six ICDs and identify the best design. The new criteria are not only better than existing criteria for comparing ICDs, but they are also specially adapted to support design development and optimization of new devices.
The complexity in configuring the CFD solver imposes a barrier for users to efficiently setup the solver and obtain satisfactory results. Such kind of deficiency becomes more obvious when it comes to simulation-based design where the CFD solver is expected to respond to design changes automatically. By applying artificial intelligence, expert systems can be used to capture the knowledge involved in CFD simulation and then assist the solver configuration. This paper proposes an expert system for both dry and wet steam simulation. According to the product design, the expert system is able to select the right module to model the steam flow. Based on the derived non-dimensional numbers, appropriate physics models can be selected to run the simulation. Grid adaption, higher order schemes, and a subroutine for advanced turbulence models help to improve the accuracy of the CFD model after rounds of simulation. The output of the expert system is a robust simulation model with accurate results which are guaranteed by flow regime validation, grid independence analysis, and error estimation. The effectiveness of the proposed system is demonstrated by the analysis of a contracted pipe. In dry steam simulation scenario, the error induced by the expert system is smaller than that of the traditional ANSYS batch mode. The results obtained by the expert system also match well the empirical results when it comes to wet steam simulation.
CFD (Computational Fluid Dynamics) requires strong expertise and extensive training to obtain accurate results. To improve the usability in the complex product development process, two new types of engineering features, fluid physics feature and dynamic physics feature, which convey the simulation intent, are proposed in this paper to achieve CFD solver setup automation and robust simulation model generation in an ideal CAD/CAE integration system. Further, the association between simulation intent and design intent is integrated with another newly defined fluid functional feature in order to achieve the consistency. Consequently, an optimal design could be achieved by considering production operation, manufacturability and cost analysis concurrently. A case study of steam assisted gravity drainage (SAGD) outflow control device (OCD) is presented to show the prospective benefits of the method.
A. Velayati, University of Alberta; M. Roostaei, RGL Reservoir Management Inc; V. Fattahpour, M. Mahmoudi, RGL reservoir Managment Inc.; A. Nouri, University of Alberta; A.B. Alkouh, College of Technological Studies; B. Fermaniuk, RGL Reservoir Management; M. Kyanpour, RGL reservoir Managment Inc. Several parameters affect the skin factor of the cased and perforated (C&P) wells completed with slotted liners. Existing skin factor models for slotted liners account for such factors as the flow convergence, pressure drop and partial production but neglect phenomena such as partial plugging of the screen or near-wellbore permeability alterations during the production. This paper discusses these factors and incorporates them into a skin model using a finite volume simulation. The finite volume analysis evaluates the skin factor as a result of pressure drop in the gap between the casing wall and the slotted liner. This skin model accounts for: 1) the perforation density and phasing, 2) slotted liner specifications, and 3) different amount of sand accumulation in the annular space between the casing and the sand screen. A semi-analytical pressure drop model is also linked to the numerical model to incorporate the skin factor due to flow convergence behind the perforations. The results of finite volume analysis reveal that a low perforation density would behave close to the open-hole completion for sand-free casing-liner annular space. Conversely, pressure drops were found to be significant for a partially or totally filled space. Additionally, it was found that the optimum completion design occurs if the slotted liner joints are in line with the casing joints. Besides, a partially perforated casing or a partially open sand screen increases the distance fluids have to travel in the annular space and intensifies the skin factor. This paper provides skin models derived for vertical and perforated wells completed with slotted liner sand screens using the finite volume simulations. Each part of the model has been verified against existing numerical models in the literature. The model improves the understanding of flow performance of the sand screens and skin factor, which in turn leads to a better design of sand control completions. Keywords: Slotted liners, Perforations, Skin, Skin pressure drop, Flow efficiency
M. Mahmoudi, V. Fattahpour, RGL reservoir Managment Inc.; M. Roostaei, RGL Reservoir Management Inc; M. Kyanpour, RGL reservoir Managment Inc.; B. Fermaniuk, RGL Reservoir Management; A.B. Alkouh, College of Technological Studies Sand control and sand management require a rigorous assessment of several contributing factors including the sand facies variation, fluid composition, near-wellbore velocities, interaction of the sand control with other completion tools and operational practices. A multivariate approach or risk analysis is required to consider the relative role of each parameter in the overall design for reliable and robust sand control. This paper introduces a qualitative risk factor model for this purpose. In this research, a series of Sand Retention Tests (SRT) was conducted, and results were used to formulate a set of design criteria for slotted liners. The proposed criteria specify both the slot width and density for different operational conditions and different classes of Particle Size Distribution (PSD) for the McMurray oil sands. The goal is to provide a qualitative rationale for choosing the best liner design that keeps the produced sand and skin within an acceptable level. The test is performed at several flow rates to account for different operational conditions for Steam Assisted Gravity Drainage (SAGD) and Cyclic Steam Stimulation (CSS) wells. A Traffic Light System (TLS) is adopted for presenting the design criteria in which the red and green colors are used to indicate, respectively, unacceptable and acceptable design concerning sanding and plugging. Yellow color in the TLS is also used to indicate marginal design. Testing results indicate the liner performance is affected by the near-wellbore flow velocities, geochemical composition of the produced water, PSD of the formation sand and fines content, and composition of formation clays. For low near-wellbore velocities and typical produced water composition, conservatively designed narrow slots show a similar performance compared to somewhat wider slots. However, high fluid flow velocities or unfavorable water composition results in excessive plugging of the pore space near the screen leading to significant pressure drops for narrow slots. The new design criteria suggest at low flow rates, slot widths up to three and half times of the mean grain size will result in minimal sand production. At elevated flow rates, however, this range shrinks to somewhere between one and a half to three times the mean grain size. This paper presents novel design criteria for slotted liners using the results of multi-slot coupons in SRT testing, which is deemed to be more realistic compared to the single-slot coupon experiments in the previous tests. The new design criteria consider not only certain points on the PSD curve (e.g., D50 or D70) but also the shape of the PSD curve, water cut, and gas oil ratio and other parameters. Keywords: Screen aperture size, Skin Factor, Open area to flow, Plugging tendency, Slotted liner design criteria
Several alloys and coating techniques have been used by industry for their anti-corrosion and anti-fouling properties in the industry. One of the major problems in thermal operation is related to silica and calcium carbonate scale. In this study, we intend to better understanding the relative scaling resistance performance of different coatings and alloys exposed to typical formation water in thermal operations. This paper provides a study on failed samples collected from various projects in Western Canada. Moreover, a review of research work on scaling properties of different materials in thermal applications will be presented. Different failed screens were collected from various projects in Western Canada. Thin section analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) joined with energy dispersive X-ray spectroscopy (EDX) were performed on collected failed pipeline samples to determine the composition of the scale material. Obtained results revealed that the main scaling materials are silicates and carbonates. Chert, clays and carbonates act as cement to bind sand grains (mainly quartz). Later, a review was performed on an ongoing investigation regarding the materials and coatings for improving the anti-scaling properties. Bulk scaling tests, Atomic Force Microscopy (AFM), and in-situ field trials were used to investigate the anti-scaling properties of two RGL proprietary grade materials, proRC05, and proRS06, as well as electroless nickel (EN) coating. Carbon steel L80, carbon steel 4140 and EN30B alloy steel were used for comparison. The microstructural change of the material surface was studied using complementary techniques (e.g., XRD, SEM, and EDX). The tests have been performed under a complex chemical environment that represents the chemistry of the near screen condition in thermal operation, to assess the relative performance of different coatings. Among proRC05, proRS06, 4140 carbon steel and EN30B alloy steel, the anti-scaling performance follows the order of proRC05 > proRS06 > 4140 carbon steel > EN30B alloy steel. Comparison between EN-coated and uncoated samples shows that the EN-coated carbon steel L80 provides better anti-corrosion and fouling resistance performance with a small amount of iron oxides and silica foulants. Field trials of EN-coated technology have been also proven to be effective. This work provides a detailed review on recent attempts on evaluating the anti-scaling properties of various materials and coatings to minimize the silica and calcium carbonate scale. Furthermore, field trials were reviewed for evaluating the scaling and corrosion properties in thermal production. The results of this study will help engineers select material for projects in which silica and calcium carbonate scaling could be a significant issue. Keywords: Silica scaling, Calcium carbonate scaling, Sand control screen, Electroless nickel coating, Thermal production, AFM/SEM/EDX
Y. Guo, University of Alberta; M. Roostaei, RGL Reservoir Management Inc; A. Nouri, University of Alberta; V. Fattahpour, RGL Reservoir Inc; M. Mahmoudi, RGL Reservoir Inc; H. Jung, University of Alberta Steam Assisted Gravity Drainage (SAGD) is the primary thermal recovery technology currently employed to extract heavy oil and high-viscosity bitumen from Alberta oil sands. In the near-wellbore region, the initial stresses are nearly zero, and as the SAGD chamber grows, the stresses tend to build up due to the thermal expansion of the formation. Also, melting of the bitumen and subsequent loss of the bonding between the grains leads to the collapse of the gap between the formation and sand control liner over time. The result will be effective stress buildup and gradual compaction of the oil sands around the liner.
As for the design criteria, the lower and upper bounds of the slot size are governed by plugging and sand production, respectively. Considering the stress effect on plugging and sanding, testing data indicate that both the lower and upper bounds should be revised to larger slot aperture sizes. View Publication
M. Mamoudi, RGL Reservoir Inc; M. Roostaei, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; A. Uzcatequi, RGL Reservoir Inc; J. Cyre, RGL Reservoir Inc; C. Sutton, RGL Reservoir Inc; Brent Fermaniuk, RGL Reservoir Inc. Although several workflows have been developed over the years for the design of the optimal sand control solutions in thermal applications, numerous sand control failures still occur every year. This paper aims at assessing the failure mechanism of different sand control techniques and the factors contributing to the failure by analyzing different failed sand control screen samples recovered from thermal and non-thermal wells.
This paper reviews the plugging mechanism of the standalone sand control screen obtained from the field to provide first-hand evidence of the plugging mechanism and provides explanations for some of the poor field performances. The results could help engineers to better understand the micro-scale mechanisms leading to sand control plugging. View Publication
J. D. M. Pallares, University of Alberta; C. Wang, University of Alberta; M. Haftani, University of Alberta; Y. Pang, University of Alberta; M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; A. Nouri, University of Alberta. This study presents an evaluation of Wire-Wrapped Screens (WWS) performance for SAGD production wells based on Pre-packed Sand Retention Testing (SRT). The impacts of features such as flow rates, water cut, steam-breakthrough events and fluid properties on flow performance and sand production are analyzed. The aim is to obtain a better understanding of WWS performance under several SAGD operational conditions for typical sand classes in the McMurray Formation in Western Canada.
This research incorporates both single-phase and multiphase flow testing to improve design criteria for wire-wrapped screens and provide an insight into their performance in thermal recovery projects. An improved post-mortem analysis includes fines production measurements to correlate these to the retained permeability caused by the pore plugging, which has hardly been evaluated in previous studies. View Publication
V. Fattahpour, RGL Reservoir Inc; M. Mahmoudi, RGL Reservoir Inc; M. Roostaei, RGL Reservoir Inc; P. Nolan, Canadian Natural Resources Limited; C. Sutton, RGL Reservoir Inc; B. Fermaniuk, RGL Reservoir Inc. With the aging of the SAGD projects and growing number of wells with hot-spot and sand production problems, there is a growing interest in the remedial completion with Inflow Control Device (ICD) and tubing deployed scab liner. The current study aims at better understanding the annular flow, sand transport in the annular space and the expected pressure drops and the produced sand for tubing deployed scab liner sand control solution using a large-scale experimental well simulator.
This paper introduces an experimental tool for evaluating the tubing deployed scab liner performance as remedial sand control in thermal applications. The developed experimental testing and facility could help to better design and evaluate the remedial tubing deployed scab liner sand control solutions. View Publication
X. Qiu, University of Alberta; M. Pan, University of Alberta; L. Gong, University of Alberta; J. Hang, University of Alberta; M. Mahmoudi, RGL Reservoir Inc; V.Fattahpour, RGL Reservoir Inc; C. Sutton, RGL Reservoir Inc; J.L. Luo, University of Alberta; H. Zeng, University of Alberta. Application of inflow control devices (ICDs) in a thermal producer has proven to be an effective solution to increase the wellbore performance and reduce production problems such as steam breakthrough. In challenging areas where the potential for scaling is greater, there is concern that the ICD could plug. Often, operators face severe nozzle plugging nozzles with silica and calcium carbonate scales. This work is intended to investigate the relative resistance of various materials to silica or calcium carbonate scaling. Bulk scaling tests on four types of coupons (4140 carbon steel, EN30B alloy steel, and two proprietary grades, proRC05 and proRS06) were conducted in the solution with similar chemical composition of common produced water in steam-assisted gravity drainage (SAGD), cyclic steam stimulation, and steamflood projects in Western Canada. Both silica scaling and calcium carbonate scaling tests were carried out to evaluate the anti-scaling performance of the material commonly used in manufacturing ICDs for these projects. The microstructure of the scale on the coupons after scaling tests were completed was investigated using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). Force measurement using the atomic force microscopy (AFM) colloidal probe technique was applied to interpret the microscopic interactions between different substrate surfaces and silica or calcium carbonate particles. The detailed investigation on evaluating the scaling resistance of different materials provides useful insights into the selection of suitable materials for projects where scaling exists as a major problem. View Publication
C. Wang, University of Alberta; Y. Pang, University of Alberta; J. Montero, Univeristy of Alberta; M. Haftani, University of Alberta; V. Fattahpour, RGL Reservoir Inc; M. Mahmoudi, RGL Reservoir Inc; A. Nouri, University of Alberta. Thermal stimulation techniques are widely used to exploit Western Canadian heavy oil assets. These techniques rely on injection of steam into the formation, inducing complex geomechanical stresses in the reservoir and surrounding strata during the life cycle of the project. In SAGD wells, the collapsed oil sand around the liner undergoes a stress buildup which causes gradual sand compaction. The stress buildup is influenced by several factors such as the in-situ stresses, reservoir poroelastic and thermal expansion, and reservoir shear dilation. However, the impact of stress level and anisotropy around the liner is not properly accounted for in previous research on slotted liner design. This paper investigates the effect of anisotropic stress buildup around slotted liners on their sanding and plugging performance under multiphase flow conditions.
The results of this study indicate that the stress and multiphase flow effects are crucial factors in the evaluation of slotted liner performance. The findings from the innovative experimental studies provide insights into the practicability of evaluating slotted liner performance with the consideration of sophisticated field conditions and optimizing the selection of the slotted liner aperture for the entire well lifespan. View Publication
L. Gong, University of Alberta; X. Qiu, University of Alberta; L. Zhang, University of Alberta; J. Huang, University of Alberta; W. Hu, University of Alberta; L. Xiang, University of Alberta; D. Zhu, RGL Reservoir Inc; R. Sabbagh, RGL RESERVOIR Inc; M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; J.L. L, University of Alberta, H. Zeng, University of Alberta. Fouling issues are highly undesirable in oil industries, and stable water–oil emulsion is one of the major causes of fouling on pipelines, upgrading equipment, and other surfaces in oil production. Studying the interfacial interactions between emulsion drops and various metal substrates is of significant importance in the fundamental understanding of fouling mechanisms. In this work, surface force measurements using a drop probe atomic force microscope technique and fouling tests were applied to investigate the fouling and antifouling mechanisms of electron-beam-deposited iron substrates with and without electroless nickel–phosphorus (EN) coatings. The effects of oil or aqueous solution conditions have been systematically investigated, including the asphaltene concentration, salinity, pH, and presence of divalent ions. A theoretical model based on the Reynolds lubrication equation and augmented Young–Laplace equation has been applied to analyze the measured force profiles. Our results indicate that the attractive van der Waals force plays an important role in the fouling phenomena, particularly under high-salinity conditions, while the repulsive electric double-layer interaction contributes to the antifouling behavior. Surface force measurements and fouling tests of Fe and EN substrates in toluene-in-water emulsions clearly demonstrate the excellent performance of the EN coating. Our work provides useful insights in the fundamental understanding of fouling/antifouling mechanisms of oil-in-water emulsions on different substrates, with implications to the development of efficient antifouling coatings and strategies in oil production processes. View Publication
WHOC, Oman Two-dimensional (2D) failure criteria such as Mohr-Coulomb are commonly used to determine the required injection pressure that result in shearing in the oil sands. Shear fractures could improve in-situ permeability and, therefore, could results in a successful in-situ recovery process. 2D failure criteria, which are usually calibrated with common triaxial tests, ignore the role of the medium principal stress. Three-dimensional (3D) failure criteria, on the other hand, consider all three principal stresses. In the current study, different three-dimensional failure criteria including Modified Lade, Modified Wiebols-Cook and Drucker-Prager were used to assess the required injection pressure to cause shear failure in oil sands. Moreover, consequences and limitation of using 3D failure criteria instead of 2D criteria are also discussed in the paper. Steam-Assisted Gravity Drainage (SAGD) projects in Alberta could be classified in three groups regarding the in-situ stress arrangement: shallow reservoirs where vertical stress is the minimum principal stress, mid-depth reservoirs where the vertical stress is the medium principal stress and deep reservoirs where the vertical stress is the maximum principal stress. For shallower SAGD projects the minimum horizontal stress (medium principal stress) is comparable in magnitude to the vertical stress (minimum principal stress). In such stress conditions, considering all three stresses in the failure criterion would not affect the injection pressure calculations significantly. However, for deeper SAGD reservoirs there is a considerable difference between the minimum and medium principal stress and application of the 3D failure criteria is more relevant. It seems that classic approach of using 2D failure criteria leads to conservative injection pressure values. On the other hand, based on the 3D failure criteria, higher injection pressures are required to cause shear failure in deeper SAGD projects. Keywords: Steam-Assisted Gravity Drainage (SAGD), 2D and 3D failure criteria, shear failure
D. Zhu, RGL Reservoir Inc; L. Gong, University of Alberta; Z. Qiu, University of Alberta; W. Hu, University of Alberta; J. Huang, University of Alberta; L. Zhang, University of Alberta; V. Fattahpour, RGL Reservoir Inc; M. Mahmoudi, RGL Reservoir Inc; J. Luo, University of Alberta; H. Zeng, University of Alberta. The scaling has been found to be a major problem in thermal production, such as in the Steam-Assisted Gravity Drainage (SAGD) operation. In addition to providing a favorite environment for corrosion, scaling could result in extreme plugging in sand control devices. Therefore, any coatings for the equipment and completion in thermal production should provide significant anti-scaling surface properties.
This paper presents a detailed study, including field and laboratory testing, on application of the Electroless Nickel Coating (EN-coating) in thermal production environment. Initially, EN-coated and uncoated carbon steel samples were tested in laboratory to assess the scale, hardness and adhesion of inorganic and organic materials.
Successful laboratory testing lead to a field testing plan, which involves deploying the EN-coated and uncoated samples into a horizontal well for thermal production. The specimens were recovered after certain time and a comprehensive X-ray Photoelectron Spectroscopy (XPS) and Energy-Dispersive Spectroscopy (EDS) were performed to assess accumulation of fouling substances on EN-coated and uncoated carbon steel.
This study suggests the application of the EN-coating technology to solve the problems caused by scale, and adhesion of organic and inorganic material in thermal production. The comprehensive laboratory testing and field data from the SAGD wells shows that EN-coating significantly improves the well integrity in the harsh thermal production environment. View Publication
M. Roostaei, RGL Reservoir Inc; A. Nouri, University of Alberta; V. Fattapour, RGL Reservoir Inc; D. Chan, University of Alberta. A central issue in hydraulic fracturing treatment in petroleum wells is the transport of proppant particles by the injection fluid. In this paper, we present an innovative proppant transport model in a fixed rectangular- and elliptic-shaped slots. The proposed model is an improvement to the current modeling of proppant transport by applying a non-oscillatory numerical scheme which has high accuracy everywhere in solution domain, even close to the steep gradients. In addition, inertia, fracture wall, and concentration effects on proppant settling along with slurry evolution as a function of proppant concentration has been considered.
This paper introduces the mathematical equations that govern the proppant transport phenomenon and discusses special front capturing numerical techniques, boundary conditions, coupling between proppant and slurry mass conservation equations and time stepping restrictions required for the solution stability. We incorporated published correlations obtained from proppant transport laboratory experiments in our numerical modelto better capture the physics of the problem. 5th- order WENO scheme was used to avoid oscillation and diffusion at the proppant front since traditional finite difference discretizationwas found to be insufficient in solving the hyperbolic transport partial differential equations. Results show that the technique used in this study can capture the proppant distribution with minimum oscillation and diffusion.
A series of sensitivity analysis was conducted to explore the legitimacy of these assumptions and to provide guidelines that allow more accurate predictions of the proppant and fluid transfer. Numerical results are presented to show how proppant distribution is impacted by the injection fluid viscosity, density difference between proppant particles and injection fluid, proppant size, and fluid flow injection rate. Results of the sensitivity analysis illustrate the significance of choosing appropriate viscosity of the injection fluid as small changes in the viscosity may cause noticeable effects on the concentration distribution. In addition, we found that variation of proppant size and density within a reasonable range have a modest effect on proppant concentration distribution.
Furthermore, we also investigated the amount of gravity driven vertical motion of proppant which is driven by density differences (convection) and compare it to a second gravity driven motion which is proppant settlement. Both of these two well recognized mechanisms can occur inside a fracture during proppant placement, however, the importance of each mechanism as a function of proppant injection design parameters is not fully understood. View Publication
V. Fattahpour, RGL Reservoir Inc; S. Azadbakht, University of Alberta; M. Mahmoudi, RGL Reservoir Inc; Y. Guo, University of Alberta; A. Nouri, University of Alberta; M. Leitch, University of Alberta. In SAGD wells, the gap between the oil sand and the sand control liner closes or collapses over time due to such factors as the oil sand thermal expansion, the melting of bitumen and the ensuing loss of the apparent bonding between the grains. The result is the buildup of effective stresses and the gradual compaction of the oil sands around the liner. Current practices for the sand control design do not account for the effect of time-dependent effective stress variation around the liner on the sand control performance. In this paper, we outline the results of an experimental study on the effect of near-liner effective stress on the performance of slotted liners. This study builds on existing experimental procedures and investigates fines migration, sand production and clogging tendency of slotted liner coupons in large-scale unconsolidated sand-packs. Sand-packs with controlled properties (grain size distribution, grain shape, and mineralogy) are packed on a multi-slot sand control coupon in a triaxial cell assembly. Varying levels of stress are applied to the sand-packs in directions parallel and perpendicular to the multi-slot coupon. For each stress level, brine is injected into the sand-pack from the top surface of the sample towards the coupon. Test measurements include pressure drops across the sand-pack and the coupon as well as the produced sand/fines mass for each stress level. Post-mortem analysis is performed to measure fines/clay concentration along the sand-pack as a direct measure of fines migration. Experimental results show that under the subsequent increase in effective stresses, sand-packs experience considerable deformations in directions parallel and perpendicular to the multi-slot coupon; which result in a drastic drop in the porosity and retained permeability. Test results show that the maximum reduction in permeability occurs in the vicinity of the multi-slot coupons due to the fines accumulation and the higher compaction in that region. In comparison to experiments with no confining stress, the application of confining stress results in lower retained permeability in the sand-packs as well as reduced sand production. This paper presents, for the first time, the effect of near wellbore effective stress on clogging tendency and sand retention characteristics of slotted liner completions. The tests allow the assessment of the adequacy of the use of existing design criteria over the life cycle of the well under variable stress conditions around the liner. View Publication
M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; A. Nouri, University of Alberta; T. Yao, University of Hong Kong; B.A. Baudet, University of Hong Kong; M. Leitch, University of Alberta. Oil sand characterization tests are essential for the selection and evaluation of sand control devices. Current approaches for screen selection and evaluation usually rely on Particle Size Distribution (PSD) and neglect the effect of important parameters such as porosity, grain shape and frictional properties. One aim of this study is to characterize oil sand’s mechanical, geometrical and size characteristics that should be considered in the completion design. Another objective is to determine if natural mixture of oil sand could be reasonably replicated with commercial sands for large-scale sand control evaluation tests. In this paper we present the results of a comprehensive image analysis and laser sieve analysis on oil sand samples from the McMurray Formation to quantify geometrical grain characteristics (sphericity, aspect ratio, convexity and angularity) of the sand grains and establish the PSD of the samples. Direct shear tests were performed to assess the frictional characteristics of different oil sands around the liner under variable stress conditions during the SAGD well lifecycle. Image analysis, PSD, and direct shear tests showed that natural mixture of oil sand could be successfully simulated with commercial sands in terms of size and shape of grains and mechanical properties. This conclusion is significant to those performing large-scale sand control evaluation tests that usually require large quantities of sands that are not readily available and require significant preparation. This paper provides the first comprehensive investigation of the granular, and geomechanical charac- teristics of oil sand from the McMurray Formation. The paper discusses the missing parameters in the design of sand control device, and evaluates test methods that measure those parameters. The proposed testing program could be used as a benchmark for oil sand characterization in relation to the design and evaluation of sand control device. View Publication
M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; A. Nouri, Univeristy of Alberta; M. Leitch, University of Alberta. The quantification of fines migration in the vicinity of sand control screens in SAGD wells is of paramount importance to operating companies, who require the wells to operate under optimum conditions for a period of 10-15 years. Fines migration can lead to the plugging of pore spaces around the liner and result in reduced permeability in the liner’s vicinity, hence, lowering the wellbore productivity. This paper investigates the fines migration in relation to slot width and density in SAGD wells. A series of laboratory experiments was performed by using a Sand Retention Testing (SRT) facility which accommodates a sand pack sample and a multi-slot coupon to represent the near-wellbore high-porosity zone and sand control liner, respectively. As fluid was pumped through the sand pack and across the slotted coupon, the pressure drop across the sand pack and coupon was measured, along with the mass and Particle Size Distribution (PSD) of produced fines and sand. After the flow test, the sand pack was dissected, and the PSD of fines portion of sand pack was measured to assess the movement and concentration of fines over the course of the test. Test observations indicate that the slot width, slot density, and the flow rate highly affect the fines migration/production and the PSD of the migrated and produced fines. Larger slot widths increase the mass of the produced and migrated fines. Further observations indicate that the mass and size of produced fines is highly dependent on the flow rate and that there is a critical rate below which little amounts of fines are produced or move in the porous medium. View Publication
M. Mahmoudi, RGL Reservoir Management Inc; S. Nejadi, University of Alberta; M. Roostaei, RGL Reservoir Management Inc; J. Olsen, University of Alberta; V. Fattahpour, RGL Reservoir Management Inc; C. F. Lange, University of Alberta; D. Zhu, RGL Reservoir Management Inc; B. Fermaniuk, RGL Reservoir Management Inc; A. Nouri, University of Alberta. The term skin is used to describe pressure drop caused by a flow restriction near the wellbore. The skin factor of wells completed using slotted liners can be explained by a number of phenomena including: the flow across the slots, flow convergence towards slots, near wellbore permeability, and occlusion of liner open area due to corrosion and scale deposition. This paper introduces an analytical skin model for the slotted liner, which incorporates these phenomena, and can be used to optimize the slotted liner design. The introduced analytical model was verified by physical and Computational Fluid Dynamics (CFD) models. The proposed analytical skin factor model for slotted liners is based on slot width, slot density, the spatial distribution of slots, and near-liner permeability. The model also incorporates partial plugging of slots. The model is validated using experimental Sand Retention Testing (SRT) data. A series of SRT experiments were conducted at different flow rates for two Particle Size Distributions (PSD) from the McMurray Formation in Northern Alberta. The experiments were also modeled by the CFD to better understand the flow dynamic near the liner. Results of the analytical model and experimental tests were generally in agreement. However, results of the analytical model deviate from experimental tests for narrow slots and high flow rates. In these cases, the analytical model predicts smaller skin than the experimental tests. For cases related to narrow slots and higher velocity the pore plugging close to the liner is significant which was not modeled in the analytical model. Moreover, for very fine sand (low permeability) sand-pack the deviation from the experimental results is higher in comparison with medium uniform sand (higher permeability) sand-pack. CFD simulations showed the effect of the slot width on the depth of the convergence zone, which is not included in the analytical model. Since the analytical model follows the experimental results for common flow rates in thermal production, the model could be used to assess the skin for different possible designs and choose the best slot specifications that minimize the skin. This paper presents the details of an analytical model for the skin factor verified by experimental data and CFD simulation. This analytical model can be used to optimize the liner specification for the best flow performance. This paper also outlines the limitations of the analytical models for calculation the skin/ pressure drop. View Publication
M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; A. Nouri, University of Alberta; T. Yao, University of Hong Kong; B.A. Baudet, University of Hong Kong; M. Leitch, Univeristy of Alberta; B. Fermaniuk, RGL Reservoir Inc. Abstract This paper presents the results of several large-scale Sand Retention Tests (SRTs), which are used to test and refine the criteria used for slotted liner design. The paper also presents the analysis of test measurements to improve the understanding of the parameters that influence the sand control performance. The parameters include Particle Size Distribution (PSD), flow rate, slot opening size and slot density. The SRT facility was commissioned to improve the existing testing methods by (1) using multiple-slot rather than single-slot coupons, (2) using more realistic sand pack preparation/saturation procedures than the existing practices, (3) measuring the pressure drop along the sand pack and across the liner coupon to assess the retained permeability and flow convergence, and (4) post-mortem analysis of the sand pack to measure fines/clay content along the sand pack as a direct measure of fines migration. Several tests were performed by varying the slot size, slot density, and PSD of the sand pack, and flow rate. The testing data were used to validate and improve the current industrial design of slotted liners. Test measurements and observations indicate that the sand pack preparation procedure highly affects the testing results. For typical field porosities and PSDs, we observed finite amount of sand production bellow the existing criteria for sanding during the SRT, for the screens designed based on existing models. Testing data also indicate smaller retained permeability for lower slot density due to converging flow. Moreover, measurements indicate lower retained permeability for narrower slot width, caused by the accumulation of fines and pore plugging in the liner's vicinity. However, larger slot width than a certain size contributes to higher levels of sanding. Three different sanding modes are identified: (1) initial sanding or sand occurrence, (2) flow rate dependent transient and (3) flow rate dependent continuous sanding. It is proposed that the sanding mode should be also included in the design criteria along with the acceptable sanding threshold. Test results indicate the combined effect of the slot size and density on both retained permeability and sand production. These findings lead to a new design approach for maximum retained permeability and acceptable sand retention. This paper introduces a new set of design criteria for slotted liners based on the results of a novel large-scale testing to evaluate the sand control for thermal heavy oil production applications. Also it provides a better understanding of the sand production and the role of the slot width and slot density on the sand production. The paper also presents an improved understanding of the sanding and permeability evolution close to the liner in relation to several liners and flow parameters. The set-up, testing procedures, and measurement methods that are used in the experiments improve the existing methods in several fronts. View Publication
In this paper, we present the results of an experimental investigation on the effect of pH and salinity on slotted liner performance in terms of sanding and retained permeability for heavy oil thermal production. This work is an advancement of the existing knowledge in the literature which indicates that pH and salinity could highly affect the mobilization, flocculation and deflocculating of clays (mainly Illite and Kaolinite) in oil sands formations. Water with different pH, in the range of 6.8 to 8.8, and salinities, in the range of 0 to 1.4 % was injected into sand pack samples supported with multi-slot coupon in a Sand Retention Testing (SRT) facility. Measurements included pressure drops along the sand pack and across the slotted liner coupon as well as the produced sand/fines for different flow rates. These measurements were used to assess the effect of the pH and salinity on fines migration within the sand pack, capability of the slotted liner to produce the fines, pore and slot plugging, sand production and the retained permeability. We observed that the pressure drops, fines production and the retained permeability are highly dependent on the pH and salinity of the injected fluid. In low pH and high salinity environment, clay is not mobilized resulting in low pressure drops and high retained permeabilities. On the other hand, an increase in pH value or a decrease in salinity leads to significant clay mobilization and a remarkable reduction in retained permeability. This paper provides a thorough experimental investigation of the pH and salinity effect on slotted liner performance. The effect of the pH and salinity is usually ignored in screen control testing while it could highly control the clay mobilization and retained permeability. Results of this study could trigger wide reconsideration in sand control approaches particularly by altering the pH in the near wellbore zone.
M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; A. Nouri, Univeristy of Alberta; S. Rasoul, University of Alberta; T. Yao, University of Hong Kong; B.A. Baudet, University of Hong Kong; Michael Leitch, RGL University of Alberta; M. Souroush, Univseristy of Trinidad and Tobago. This paper presents the characterization of oil sands from the McMurray Formation. The main objective of this paper is to investigate the possibility of replicating the oil sands by the mixtures of commercial sands and fines for large-scale testing. There is a growing interest in large-scale evaluation testing for sand control devices that require considerable amounts of representative oil sands materials. However, natural representative oil sands samples are usually not available or are limited in quantity. Therefore, replicating the oil sands is essential for such tests. Twenty-three oil sands samples were collected from two wells in the McMurray Formation and cleaned using the Soxhlet extraction technique. The cleaned samples were examined using the image analysis technique and Scanning Electron Microscope (SEM) imaging to study their Particle Size Distribution (PSD), shape factors, mineralogy, and texture. Similar analysis was performed on eleven series of commercial sands to compare their shape, mineralogy, and texture with those of oil sands. Particle Size Distribution of 10 commercial fines was also analyzed with a particle sizer to cover the required fine/clay part of the duplicated samples. Direct shear and 1D consolidation were performed to compare the mechanical properties of the oil sands samples and the duplicated mixtures of commercial sands and fines. The shape factors of the oil sand and the selected commercial sand samples are in close agreement. In addition to the common average/cumulative shape factor measurements, this paper also presents the variation of shape factors within each sample for different grain sizes. The results show the same sand shape characteristics among all oil sand samples as well as the tested commercial sands. Further, XRD results indicate a similar mineralogy for the commercial sands and the oil sands samples. The SEM images show random changes in the surface texture of both oil sands and commercial sands with no observable trends. We were able to use commercial sands and fines mixture with similar grain shape properties to duplicate the PSD of the oil sand samples. Direct shear and 1D consolidation testing of the oil sands and samples made of commercial sands and fines show similar consolidation and frictional properties for both the duplicated mixture and cleaned oil sands for the same compaction level (porosities). This paper provides a procedure for duplicating the oil sands with commercial sands and fines. It also provides detailed information on the mineralogy, texture, and the variation of the shape characteristics for oil sands from the McMurray Formation. View Publication
There is a growing interest in physical model testing of the reservoir and large-scale sand control testing for oil sands. These experiments require the synthesization of representative sand-packs. Particle size distributions (PSDs) of these sand-packs ought to be comparable to the PSD of target oil sands. For practical and economic reasons, it is favorable to test samples with a limited number of PSDs, yet representative of a spectrum of oil sands. The aim of this paper is to categorize the PSD of Alberta oil sands to a limited but representative number for use in laboratory research. This paper is based on the analysis of 152 PSD curves for Alberta oil sands. To categorize these PSD's in a meaningful way, an algorithmic approach is presented which uses attributes that are widely used in sand control design (e.g. D10, D50, D70, fines content) and, subsequently screens and sorts the data to produce a finite number of PSD categories which represent the majority of the data. Rules are implemented in the algorithm to limit the number of categories (≤7), and require that each category cover a significant subset of the total data (≥10%). A review of the published PSDs for oil sands across Alberta indicates a significant variation in the PSD curves even within the same reservoir. However, in spite of the fact that PSD data show a large variation, PSD categories can be identified to build representative oil sand samples for design and testing purposes. For the database used in this investigation, four major and two minor PSD classes were identified. These six PSD classes, cover more than 87% of the analyzed PSDs. Introduced classes and existing PSD classifications in the literature share interesting similarities. However, certain differences, such as the lack of very coarse ranges (D50~500 µm) was observed. The method which is introduced for oil sand classification is based on the D-values which are commonly used in screen aperture design. This method provides a useful tool for both screen designers and researchers to categorize and focus their work on a specific set of representative PSDs, rather than a wide distribution of PSDs. View Publication
M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; M. Roostaei, RGL Reservoir Inc; O. Kotb, University of Alberta; C. Wang, University of Alberta, A. Nouri, University of Alberta; C. Sutton, RGL Reservoir Inc; B. Fermaniuk, RGL Reservoir Inc. The term skin is used to describe pressure drop caused by a flow restriction near the wellbore. The skin factor of wells completed using slotted liners can be explained by a number of phenomena including: the flow across the slots, flow convergence towards slots, near wellbore permeability, and occlusion of liner open area due to corrosion and scale depo"In Steam Assisted Gravity Drainage (SAGD) projects, it is essential to heat the reservoir evenly to minimize the potential for the localized steam breakthrough. Steam breakthrough can cause erosive damage to the sand control liner by the flow of high-velocity wet steam, and, in extreme cases, can compromise the mechanical integrity of the liner. This research investigates the sanding mechanism during the high-quality steam injection into the SAGD production wells. A large-scale Sand Retention Test (SRT) was used to investigate the role of steam breakthrough in the sand control performance. Produced sand and pressure drops along the sand-pack were the main measurements during the tests. The test procedure and test matrix were designed to enable the examination of the impact of steam breakthrough on sand production for different steam rates. Two possible sanding mechanisms are postulated in steam breakthrough events: (1) local grain disturbance caused by the high-velocity steam near the liner, (2) effect of the complex phase behavior of the steam and the subcool level. Two different testing procedures were designed to examine these mechanisms. The local grain disturbance mechanism was investigated by injecting air at a wide range of velocities. Results indicate that this mechanism could not lead to a significant sanding when there is a bit of effective stress near the liner. Hence, it looks like that the steam velocity poses a higher risk in early stages of SAGD production when the near-liner stress is very low. The effect of high-pressure high-temperature (HPHT), low- to high-quality steam flow and the subcool level will be investigated in the next phase of the study. This work addresses the effect of high-quality steam breakthrough on the sand control performance of the liner in SAGD producer wells. The findings in this paper help the researchers to direct their research to better understand the steam breakthrough. This research will eventually help the engineers in their liner design and evaluation for the entire wellbore life cycle as the near-well stress evolves. View Publication
J.D. Montero, University of Alberta; S. Chissonde, University of Alberta; O. Kotb, University of Alberta; C. Wang, University of Alberta; M. Roostaei, RGL Reservoir Inc; A. Nouri, University of Alberta; M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc. This paper presents a critical review of current evaluation techniques for the selection and design of sand control devices (SCD) for Steam Assisted Gravity Drainage (SAGD) wells. With the industry moving towards exploiting more difficult reservoirs, there is a need to review the current testing methods and assess their adequacy for sand control evaluation for different operational and geological conditions. In addition to a critical review of existing sand control testing approaches for SAGD, the paper also discusses the testing parameters in previous studies to evaluate their representativeness of the field conditions in terms of interstitial seepage and viscous forces, and flow geometry. Moreover, the paper reviews the analysis and results of sand control testing in the literature and assesses the sand control design criteria in terms of the level of acceptable sand production and plugging. Furthermore, the review evaluates the suitability of the sample size, sand preparation techniques, representation of the SCD in the testing, and experimental procedures. The review shows variations in the existing sand control testing in SAGD, in terms of not only approach, sand control representation, and sample size, but also regarding operational test conditions, such as flow rates and pressures. Ideally, large-scale pre-packed tests that include the effects of temperature and radial flow geometry would more closely emulate the actual conditions of SAGD wells than most existing tests allow. High temperatures may affect sanding and plugging through changes in wettability, permeabilities, and mineral alterations. Further, the varying velocity profile in radial flow towards the SCD influences the fines migration pattern differently from the linear-flow conditions in the existing Sand Retention Tests (SRT). However, large-scale radial-flow tests are constrained by cost and complexity. Most SRT experiments have employed high flow rates, exceeding the equivalent field rates. Utilizing realistic rates for the tests and appropriately capturing the actual fluids ratios, water cuts and steam breakthrough scenarios can improve the quality of testing data. Accordingly, existing SRT experiments can be designed to incorporate, if not all, but some of the relevant physics in SAGD by employing representative viscosities, flow rates, fluid properties and ratios, stress conditions and obtain suitable live and post-mortem measurements. This critical review compiles various aspects of current sand retention tests and evaluates their applicability to SAGD well conditions. It serves as a starting point for future research by providing an overview of existing testing methods, highlighting the strengths and opportunities for improvements. View Publication
V. Fattahpour, RGL Reservoir Inc; M. Mahmoudi, RGL Reservoir Inc; M. Roostaei, RGL Reservoir Inc; C. Wang, University of Alberta; O. Kotb, University of Alberta; A. Nouri, University of Alberta; C. Sutton, RGL Reservoir Inc; B. Fermaniuk, RGL Reservoir Inc. Injector wells in thermal field developments in Western Canada are usually completed by slotted liners. The purpose of liner installation is preventing sand production after a shut-in, keeping a stable wellbore, and providing an appropriate steam distribution. The objective of this paper is to quantify the role of slot width and slot density on the sanding performance of the liner in cycles of injection and shut-in in a SAGD injection well, through a series of laboratory sand control tests. A large-scale sand retention testing facility was developed and employed to conduct a series of tests on slotted liner coupons with different slot widths and densities. These tests were tailored to simulate steam injection and backflow during the shut-in. Three representative particle size distributions for the McMurray Formation were used in this study ranging from coarse to fine sand. The experimental set-up allows to measure the amount of produced sand. Since the produced sand in steam injection wells is not usually cleaned out, the acceptable threshold for sand production in the injector should be more conservative than the same for producer wells. Testing results indicate that the sand control performance of the liner is governed by the slot width and density, and formation particle size distribution. Results indicate a negligible amount of produced sand with gas backflow for a properly designed liner even at very high gas velocities. Historically, there has been little attention to the sand control design for injector wells. This work highlights the significance of slot density and slot width in the sand control performance for steam injection wells. The paper provides the basis for the proper design of an effective sand control in SAGD injectors. View Publication
V. Fattahpour, RGL Reservoir Inc; M. Mahmoudi, RGL Reservoir Inc; C. Wang, University of Alberta; O. Kotb, University of Alberta; M. Roostaei, RGL Reservoir Inc; A. Nouri, University of Alberta; B. Fermaniuk, RGL Reservoir Inc; A. Sauve, RGL Reservoir Inc; C. Sutton, RGL Reservoir Inc. Stand-alone sand screen (SAS) is proven to be effective for sand control in unconsolidated sands in thermal wells. The characteristic design parameter to specify SAS is the aperture size, while the Open to Flow Area (OFA) is chosen to balance between the mechanical integrity of the screen, the completion cost, and the plugging risk. The objective of this study is to compare the performance of common SAS types for a certain geological condition. A series of three-phase large-scale sand retention tests (SRTs) is performed on slotted liner, wire-wrapped screen, and punched screen coupons. The tests are performed using two common representative PSDs of the McMurray Formation. The test matrix includes the common aperture sizes and OFA for each screen and PSD based on the current best practices in the industry. The test procedure is designed to mimic the near wellbore flow velocities, with three-phase flow ranging from 0%-100% water cut and produced gas-oil ratio ranging from 0-277 scf/bbl. The gas flow was supposed to simulate the steam breakthrough incidents. Live measurements are obtained of the sanding amount and pressure drops along the sand-pack and across the screen. Screen plugging is assessed after the completion of each test. The sanding and flow performance are shown to be a function of the aperture size, PSD, near-wellbore flow velocities, and the water cut. In low fluid flow rates, all the screen types show minimal pressure drops and perform similarly. As near-wellbore velocities increase or gas flow occurs, pressure drops show a significant increase for all devices. Results show OFA, aperture size, and screen type affect the pressure drop and sanding. In all cases, the produced sand in three-phase flow is the determining design parameter for the upper-bound acceptable aperture. The gas flow is observed to accompany large amounts of sanding for larger aperture sizes. Further, test results indicate high pressure drops for three-phase flow conditions. Test results reveal the complexity of the interaction between different design parameters, which affect the sand and flow performance, hence, necessitating an SRT test for each specific case. This paper presents the results of physical model testing of different standalone screens in terms of flow performance and sand control. This will help to identify the main factors that influence the performance of each specific screen type and develop the rationale for the screen type selection in new developments. View Publication
C. Sun, University of Alberta; S. Shuang, University of Alberta; H. Zeng, University of Alberta; V. Fattahpour, RGL REservoir Inc; M. Mahmoudi, RGL REservoir Inc; J.L. Luo, University of Alberta. In this study, a high-phosphorus Ni-P coating was prepared by electroless deposition method. The characteristics and corrosion property of electroless Ni-P coating were investigated by surface analysis techniques and electrochemical measurements, and compared with L80 steel, corrosion resistant alloys such as 13Cr steel, 316L stainless steel, Inconel and 28Cr steel. The results showed that the high- phosphorus Ni-P coating with amorphous structure contained 88.3 wt.% Ni and 11.7 wt.% P, and improved the corrosion resistance of L80 steel substrate by more than 90 % in Cl-containing medium. The corrosion resistance of Ni-P coating was close to 13Cr steel but lower than Inconel, 316L stainless steel and 28Crsteel. Nevertheless Ni-P coating, similar to Inconel and 28Crsteel, had better resistance to pitting corrosion than 13Cr steel and 316L stainless steel in Cl-containing environment. View Publication
M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; A. Nouri, University of Alberta; M. Leitch, University of Alberta. This paper presents the results of an experimental investigation to determine the mechanisms of pore plugging and permeability reduction near SAGD screen liners. The aim is to arrive at a liner design that maximizes wellbore productivity without compromising the sand control function of the liner. We set up a large-scale Sand Retention Testing (SRT) facility that accommodates a multi-slot liner coupon at the base of a sand-pack with representative grain shape and particle size distribution (PSD) of typical oil sands. Brine is injected at different flow rates and pressure differences across the coupon and the sand-pack as well as the mass and PSD of the produced sand and fines are measured during the test. Further, the PSD and concentration of migrated fines (<44 microns) along the sand-pack are determined in a post-mortem analysis. The testing results are used to assess the effect of slot size and slot density on the sand control performance as well as pore-plugging and permeability alterations near the sand-control liner. We observed that the slot size, slot density and flow rate highly affect the concentration and PSD of produced fines as well as accumulated fines (pore clogging) above the screen. For the same flow rates and total injected pore volume, wider screen aperture and higher slot density result in lower fines accumulation above the screen but more sanding. Further, the variation of slot density alters the flow convergence behind the slots, hence, the size and concentration of mobilized fines. Results indicate that higher fines concentration near the screen reduces the retained permeability, hence, lowers the wellbore productivity. This paper provides a new insight into pore plugging and fines migration adjacent the sand control liner. It also introduces a new testing method to optimize the design of sand control liners for minimum productivity impairment in SAGD projects. View Publication
M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; C. Wang, Universtiy of Alberta; O. Kotb, University of Alberta; M. Roostaei, Univeristy of Alberta; A. Nouri, Univeristy of Alberrta, B. Fermaniuk, RGL Reservoir Inc; A. Sauve, RGL Reservoir Inc; C. Sutton, RGL Reservoir Inc. Sand production is not usually considered a major concern during the injection phase in injection wells. However, well shut-in for service requirements or sudden pump failure, hence the backflow towards the wellbore and potential generation of water hammer pressure pulsing, can lead to massive sand production under favorable conditions. With the aim of sanding prevention, this paper examines the design criteria for standalone screens (SAS) in injection wells using a novel sand control testing facility. This paper presents a new large-scale sand retention testing (SRT) facility to simulate the effect of pressure pulsation and backflow in injection wells on the sand control performance of SAS. The SRT facility can be used in the selection of the best sand control method for injector wells. It can be also used to provide further understanding on the impact of formation damage on well injectivity decline, as well as study the effect of water hammer pressure pulsation on sand production in injection wells. Test results show a rapid fall off in the pressure and drastically high backflow rates due to the sudden shut-in. Higher pressure drops are observed to result in a greater backflow volume and a longer backflow period. Results also show that the slot width has a drastic influence on the sanding performance of the screen. Testing observations, for the studied PSD, indicate that the injection well requires narrower slots 1.4 D10 to meet the sand production requirements due to a high fluidization potential in the near-screen zone. Higher flow velocities during the backflow period and the tossing effect caused by the pressure waves increase the sanding potential. The produced sand during the backflow period, is observed to mainly relate to the ratio of the slot width to the mean formation grain size. It is observed that higher effective stresses around the screen work towards stabilizing the sand bridges and reducing the amount of produced sand. This paper presents a new experimental test facility for the sand control type selection and evaluation for injection wells with the aim of limiting the amount of produced sand and sustaining the wellbore injectivity. The proposed testing facility allows the performance comparison of different sand control devices and designs. View Publication
M. Roostaei, RGL Reservoir Inc; O. Kotb, University of Alberta; M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; C. Wang, Universityof Alberta; A. Nouri, University of Alberta; B. Fermaniuk, RGL Reservoir Inc. Open hole gravel pack (OHGP) has been broadly used for completion of steam-drive production wells. However, some failures have been observed with the gravel pack in such complex completions. This paper aims to better understand the OHGP performance in steam-drive production wells and examine the performance of rolled-top and straight-cut slotted liners using a large-scale Sand Retention Testing (SRT). A large-scale SRT facility was developed to investigate the performance of the gravel pack in two-phase flow regime. The testing set-up allows for co-injection of oil and brine at controlled flow rate and water cut level to emulate different scenarios for two-phase flow across the gravel pack and sand screen/liner. Testing measurements included produced sand, absolute pressures, and differential pressure drops across the slotted liner, gravel pack, gravel-sand pack interface and sand pack. The test procedure and test matrix were designed to enable an accurate assessment of the gravel pack and slotted liner performance for different fluid flow scenarios. Rolled-top and straight-cut slotted liner coupons were used for this study. Test results showed negligible sand production for both rolled-top and straight-cut slotted liners, however the produced sand was slightly higher for the rolled-top profile. The pressure drop across the rolled-top liners were smaller than the straight-cut liners based on the analytical analysis presented in this study. The results have also shown that a key factor in gravel packing performance is the ratio of the gravel pack size to the formation sand (sand pack) size. Larger gravels allow an easier production of the fines, while smaller gravels may trap the fines and be plugged over time. This work provides a robust testing facility to address the gravel pack performance in steam-drive producer wells. The results help the engineers with gravel pack and sand control design and an evaluation for the entire wellbore life. View Publication
V. Fattahpour, RGL Reservoir Inc; M. Mahmoudi, RGL Reservoir Inc; A. Nouri, University of Alberta; M. Leitch, University of Alberta. Several sand control techniques have been used in SAGD wells in Western Canada. For most projects, slotted liners have been the sand control of choice for its economics, ease of use, and acceptable performance. Careful design of the slot geometry is crucial to maintaining long-term wellbore performance but is not an easy task in formations with high fines content and other challenging characteristics, such as in Grand Rapids or shoreface at the upper member of McMurray. The primary objective in the design of sand control is to minimize the production of sand and maximize the retained permeability in the liner’s vicinity by allowing the production of any mobilized fines, avoiding extreme pressure drops by minimizing the curvature of flow streamlines around the slots, and avoiding the plugging of slots over time. Design practices for sand control in SAGD wells are currently based mostly on Particle Size Distribution (PSD) and the fines (<44um) content. Where designers focus principally on retaining sand rather than maximizing the retained permeability in the liner’s vicinity, there is an increased risk of underperforming completion designs. However, long-term well performance requires a reasonable tolerance for solids production. This paper provides a critical review of existing design criteria and the experimental testing and techniques for assessing the sand control design for SAGD production wells. It reviews the mechanisms which cause sand production and fines migration in relation to the PSD of oil sands and the formation clay and silt content. In addition, the paper presents field failure cases from the literature and examines the common problems with different types of sand control. Finally, practical recommendations are presented to further improve the sand control experiments and the current design criteria to achieve higher productivity index, lower skin buildup, and greater durability of sand control screens. View Publication
M. Roostaei, University of Alberta; A. Nouri, University of Alberta; V. Fattahpour, University of Alberta; M. Mahmoudi, University of Alberta; M. Izadi, Louisiana State University; A. Ghalambor, Oil Center Research International; B. Fermaniuk, RGL Reservoir Inc. Standalone screen (SAS) design conventionally relies on particle size distribution (PSD) of the reservoir sands. The sand control systems generally use D-values, which are certain points on the PSD curve. The D- values are usually determined by a linear interpretation between adjacent measured points on the PSD curve. However, the linear interpretation could result in a significant error in the D-value estimation, particularly when measured PSD points are limited and the uniformity coefficient is high. Using the mathematical representation of the PSD is an efficient method to mitigate these errors. The aim of this paper is to assess the performance of different mathematical models to find the most suitable equation that can describe a given PSD. The study collected a large databank of PSDs from published SPE papers and historical drilling reports. These data indicate significant variations in the PSD for different reservoirs and geographical areas. The literature review identified more than 30 mathematical equations that have been developed and used to represent the PSD curves. Different statistical comparators, namely, adjusted R-squared, Akaike's Information Criterion (AIC), Geometric Mean Error Ratio, and Adjusted Root Mean Square Error were used to evaluate the match between the measured PSD data with the calculated PSD from the formulae. The curve fit performance of the equations for the overall data set as well as PSD measurement techniques were studied. A particular attention was paid towards investigating the effect of fines content on the match quality for the calculated versus measured curves. It was found that certain equations are better suited for the PSD database used in this investigation. In particular, Modified Logestic Growth, Fredlund, Sigmoid and Weibull models show the best performance for a larger number of cases (highest adjusted R-squared, lowest Sum of Squared of Errors predictions (SSE), and very low AIC). Some of the models show superior performance for limited number of PSDs. Additionally, the performance of PSD parameterized models is affected by soil texture: For higher fines content, the performance of equations tends to deteriorate. Moreover, it appears the PSD measurement techenique can influence the performance of the equations. Since the majority of the PSD resources used here did not mention their method of measurement, the effect of measurement technique could only be tested for a limited data, which indicates the measurement technique may impact the match quality. Fitting of parameterized models to measured PSD curves, although well known in sedimentology and soil sciences, is a relatively unexplored area in petroleum applications. Mathematical representation of the PSD curve improves the accuracy of D-values determination, hence, the sand control design. This mathematical representation could result in a more scientific classification of the PSDs for sand control design and sand control testing purposes. View Publication
M. Mahmoudi, University of Alberta. This thesis presents experimental results obtained using a novel Sand Retention Testing (SRT) facility. The testing results and interpretations provide an improved understanding of the parameters that affect sand control performance in Steam Assisted Gravity Drainage (SAGD) operations. The SRT testing data are used to develop a set of new design criteria for slotted liners based on parametric testing. The SRT facility was designed and commissioned to address limitations in existing testing methods for sand control evaluation. The facility uses multiple slots in the slotted liner coupon instead of a single slot in the existing facilities. Measurements are also improved by obtaining pore pressures along the sand pack in addition to the pressure drop across the liner coupon to assess the retained permeability and flow convergence. More realistic methods are designed and used for sand pack preparation, fluid injection, and sample saturation than the existing practices. The testing also includes post-mortem analysis to measure fines/clay content above the screen and in the produced fluids to evaluate fines migration and the potential for pore plugging. Slotted liner coupons in this research vary in slot size and density and are tested for select PSDs. Testing data are analyzed to evaluate existing heuristic liner design models and propose new design criteria. Test measurements and observations indicate that the sand packs preparation procedure, injected fluid velocity, and ionic concentrations highly affect the testing results. For typical field porosities and PSDs, sand production is observed to stay within acceptable limits for the screens designed based on existing models. View Publication
L. Li, University of Alberta; C.F. Lange, University of Alberta; Y. Ma, University of Alberta. Multiple-view feature modeling is supposed to keep the information consistency during product development. However, for products involving fluid flow, the information consistency is difficult to keep because the application of CFD (Computational Fluid Dynamics) requires specific knowledge and rich experience. To conquer this deficiency, intelligent CFD solver functions toward an expert system are proposed to update the CFD analysis view in response to the changes in the design view which is embedded in the CAD fluid functional features. The CAE interface protocol is used to convert the features in the design view into the CAE boundary features in the CFD analysis view. The CFD analysis view also includes the fluid physics features and dynamic physics features which support the intelligent CFD solver functions. The intelligent CFD solver is enhanced with the capability to model complex turbulent phenomena and estimate the discretization error. A case study of contracted pipe is illustrated to show the effectiveness of the proposed multiple-view feature modeling method by comparing with empirical results. View Publication
L. Li, University of Alberta; C.F. Lange, University of Alberta; Y. Ma, University of Alberta. Computational fluid dynamics has been extensively used for fluid flow simulation and thus guiding the flow control device design. However, computational fluid dynamics simulation requires explicit geometry input and complicated solver setup, which is a barrier in case of the cyclic computer-aided design/computational fluid dynamics integrated design process. Tedious human interventions are inevitable to make up the gap. To fix this issue, this work proposed a theoretical framework where the computational fluid dynamics solver setup can be intelligently assisted by the simulation intent capture. Two feature concepts, the fluid physics feature and the dynamic physics feature, have been defined to support the simulation intent capture. A prototype has been developed for the computer-aided design/computational fluid dynamics integrated design implementation without the need of human intervention, where the design intent and computational fluid dynamics simulation intent are associated seamlessly. An outflow control device used in the steam-assisted gravity drainage process is studied using this prototype, and the target performance of the device is effectively optimized. View Publication
L. Li, University of Alberta; Y. Ma, University of Alberta; C. F. Lange, University of Alberta. CFD (Computational Fluid Dynamics) requires strong expertise and extensive training to obtain accurate results. To improve the usability in the complex product development process, two new types of engineering features, fluid physics feature and dynamic physics feature, which convey the simulation intent, are proposed in this paper to achieve CFD solver setup automation and robust simulation model generation in an ideal CAD/CAE integration system. Further, the association between simulation intent and design intent is integrated with another newly defined fluid functional feature in order to achieve the consistency. Consequently, an optimal design could be achieved by considering production operation, manufacturability and cost analysis concurrently. A case study of steam assisted gravity drainage (SAGD) outflow control device (OCD) is presented to show the prospective benefits of the method. View Publication
L. Li, University of Alberta; Y. MA, University of Alberta; M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; C.F. Lange, University of Alberta. Effective steam distribution in the injector is the key to achieve efficient and uniform reservoir heat up in SAGD operation. The focus of this research is on simulating the flow dynamics in outflow control device (OCD), the annular space between the liner and tubing, the slots, and the gap between the slotted liner and formation, using computational fluid dynamics (CFD). The objective is to use the approximated metamodel to optimize the OCD design and achieve more even steam distribution through the slots. A CFD model of the steam is developed through a systematic investigation of different domain sizes to study the effect of the pressure drop across the nozzle and the steam distribution. An evenness factor is proposed to quantify the overall steam distribution and to identify problematic slot areas. Based on the developed model, the OCD design is simplified and parameterized to conduct optimization efficiently. With the CFD expert system for steam simulation, the robust simulation models corresponding to different designs are obtained, providing accurate simulation results to the optimization algorithm. Using metamodeling, the response to the five design variables is derived, and the optimum is obtained subsequently. A cylindrical region representing the vicinity of the liner is added to the periphery of the slots to translate the optimization results into the realistic design. The CFD simulation and OCD design optimization show that the steam distribution is highly controlled by the OCD design, mainly by the nozzles’ distance to the central plane. The novel evenness factor provides a quantitative assessment of the effect of design changes and it enables the application of advanced design optimization algorithms. Fifty-five numerical experiments are conducted to obtain the relationship between the proposed evenness factor and the design variables. The overall design of the OCD can be fine-tuned to account for the steam distribution. At the beginning of the heating cycle, some flow reversal is found in some specific slots, which may lead to sand production, plugging and erosion. When the distance between the two sets of nozzles is extended to 50 mm, the normalized evenness factor shows that the steam distribution can be improved by 12.5% from the original design in which the distance used to be zero. Moreover, the velocity magnitudes in the reverse flow affected region are also reduced in the optimized design. The CFD simulation is a powerful tool to understand the flow dynamics through OCDs. This study applies a robust CFD model to investigate the complex flow interactions that affect steam distribution through OCDs to improve their design and thus to improve the steam distribution. The provided model and the design optimization algorithm could ultimately improve the heating efficiency. View Publication
L. Li, University of Alberta; Y. Ma, University of Alberta; C.F. Lange, Univeristy of Alberta. The complexity in configuring the CFD solver imposes a barrier for users to efficiently setup the solver and obtain satisfactory results. Such kind of deficiency becomes more obvious when it comes to simulation-based design where the CFD solver is expected to respond to design changes automatically. By applying artificial intelligence, expert systems can be used to capture the knowledge involved in CFD simulation and then assist the solver configuration. This paper proposes an expert system for both dry and wet steam simulation. According to the product design, the expert system is able to select the right module to model the steam flow. Based on the derived non-dimensional numbers, appropriate physics models can be selected to run the simulation. Grid adaption, higher order schemes, and a subroutine for advanced turbulence models help to improve the accuracy of the CFD model after rounds of simulation. The output of the expert system is a robust simulation model with accurate results which are guaranteed by flow regime validation, grid independence analysis, and error estimation. The effectiveness of the proposed system is demonstrated by the analysis of a contracted pipe. In dry steam simulation scenario, the error induced by the expert system is smaller than that of the traditional ANSYS batch mode. The results obtained by the expert system also match well the empirical results when it comes to wet steam simulation. View Publication
L. Li, University of Alberta; C.F. Lange, University of Alberta; Y. Ma, Univeristy of Alberta. Outflow Control Device (OCD) is applied in Steam Assisted Gravity Drainage (SAGD) to control the steam split to the formation from the injection well. The detailed analysis of OCD with CFD is desired to obtain comprehensive understanding of the flow in the device and guide design optimization. The simulation presented here is based on a commercial OCD product applied in industry. With ANSYS/CFXTM, the simulation research was carried out by phases. According to the analysis of OCD application conditions, the simulation of a small quarter domain is conducted to test the boundary conditions and the OCD flow behavior corresponding to different pressure drops. The steam distribution is believed to have an effect on the efficiency of heating. To evaluate the effect of different design on steam distribution, the simulation of half domain with different gap sizes was further processed; two parameters have been identified to quantify the steam distribution. A simulation scenario of a 360°domain is introduced at last to discover the interaction between the steam flowing through the four orifices. View Publication
Steam Assisted Gravity Drainage (SAGD) has been applied as a reliable oil recovery technology in the oil sand industry. In order to increase the productivity of the SAGD process, Outflow Control Devices (OCD) are used to control the injection of steam into the formation. Our work aims at the modelling of OCD with Computational Fluid Dynamics (CFD). In this paper, CFD simulation of OCD has been done based on a simplified model. The mechanism how OCD controls the flow is studied through a series of test simulations. Different models have been compared to study the effect of the setup details on the OCD flow. In the future, more accurate models will be established evolving from the results obtained currently and further investigation to be done into the problem.
M. Miersa, University of Alberta; M. Mahmoudi, RGL Reservoir Inc; V. Fattahpour, RGL Reservoir Inc; L. Li, University of Alberta; C.F. Lange, University of Alberta. In steam injection thermal recovery, it is essential to have a uniform flow to improve the recovery and to avoid the localized steam breakthrough which could lead to damage to well completion. In this paper, we propose three quantitative criteria to assess the performance of inflow control devices (ICD) based on computational fluid dynamics (CFD) modeling. The new performance criteria are exemplified in the evaluation of a few basic ICD designs. To evaluate the response of the ICD to flow rate and fluid type, three new performance criteria, defined as (1) quadratic flow coefficient, (2) viscosity coefficient, and (3) erosion potential, are proposed and evaluated based on a set of CFD simulations. The first criterion measures the flow rate response and the ability of the ICD to restrict high velocity flow, the second quantifies the viscosity sensitivity, and the third predicts the potential for erosion in the device. Four different liner deployed ICD designs, based on two passive design types (nozzle and channel) and one autonomous design type (Tesla flow diode), were analyzed using a rigorous CFD model. The model includes the surrounding slotted liner and inner tubing to identify any interactions of the ICD with the surrounding completion. The CFD model has been verified for grid and domain independence and it was applied to a range of flow rates representative of the field condition. In addition, simulations were run for a range of single-phase incompressible fluids with varying viscosities. Using the newly proposed criteria, the ICDs were evaluated and compared. The comparison shows that, of these devices, the diode does the best job of restricting the flow at high flow speeds and low viscosities. At high viscosities, such as in the case of oil, the diode is the least restrictive device. Although the two straight nozzles tested are slightly worse at restricting the flow, they have the lowest erosion potential. Based on this comparison and the proposed criteria, the channel design performs poorly. At low viscosities it does not sufficiently restrict the flow, and at high viscosities it overly restricts the production of oil. It also has a high erosion potential, because of the steep entrance angle. In this work, a new set of quantifiable criteria are defined and assessed that allow multiple aspects of different ICD designs to be compared simultaneously. Overall, these three criteria give a highly sensitive, quantitative means of comparing ICD designs. With these three criteria together, a more comprehensive comparison can be made in support of selection and improvement of ICDs. View Publication
M. Miersma, University of Alberta. One of the main methods of extracting oil from deep oil sands deposits is through the use of steam assisted gravity drainage (SAGD). For the best performance, inflow control devices (ICDs) are implemented along the production well to even out production and restrict unwanted fluids. To compare and evaluate these devices, three criteria are proposed: the quadratic flow coefficient, the viscosity sensitivity, and the erosion potential. These criteria are designed to be tied to specific aspects of the flow. The dependence of the criteria on the flow and viscosity is reduced by calculating the criteria from a range of data, using a least squares fit. To test the criteria, CFD simulations are performed for six devices: a 15 degree nozzle, a 40 degree nozzle, a long channel, an expanding nozzle, a device based on Tesla’s fluidic diode, and a vortex based device. Using these simulations, the three criteria are calculated for each device. The criteria are then compared to the flow results and examined for flow and viscosity independence. Although the criteria still show some dependence, they provide an improved means of comparing and analyzing ICDs. View Publication
In steam injection thermal recovery, it is essential to have a uniform flow to improve the recovery and to avoid the localized steam breakthrough which could lead to damage to well completion. In this paper, we propose three quantitative criteria to assess the performance of inflow control devices (ICD) based on computational fluid dynamics (CFD) modeling. The new performance criteria are exemplified in the evaluation of a few basic ICD designsComputational fluid dynamics (CFD) has been extensively used for fluid flow simulation and thus, guiding the flow control device design. However, CFD simulation requires explicit geometry input and complicated solver setup, which is a barrier in case of the cyclic CAD/CFD integrated design process. So far, tedious human interventions are inevitable to fill the gap. To fix this issue, this research proposes a theoretical framework where the CFD solver setup can be intelligently assisted by the simulation intent capture. Five innovative feature concepts are proposed. The fluid functional feature is used to capture the design intent while the fluid physics feature and dynamic physics feature present the simulation intent. The inter-feature associations are established by CAE boundary features and effect features. These feature concepts are defined based on the need of CAD/CFD integration and intelligent CFD solver functions for steam simulation. A prototype software tool has been developed for intelligent CAD/CFD integration, where the design intent and CFD simulation intent are associated seamlessly. An outflow control device (OCD) model, used in the steam assisted gravity drainage (SAGD) process, is studied by applying this prototype, and the target performance of this design is effectively reflected and virtually improved. The optimization result is further validated by a realistic OCD model from the industry, which confirms the software tool can provide design guidance for better steam even distribution. Therefore, it proves that the proposed method is capable of supporting complex design optimization in practice.. To evaluate the response of the ICD to flow rate and fluid type, three new performance criteria, defined as (1) quadratic flow coefficient, (2) viscosity coefficient, and (3) erosion potential, are proposed and evaluated based on a set of CFD simulations. The first criterion measures the flow rate response and the ability of the ICD to restrict high velocity flow, the second quantifies the viscosity sensitivity, and the third predicts the potential for erosion in the device. Four different liner deployed ICD designs, based on two passive design types (nozzle and channel) and one autonomous design type (Tesla flow diode), were analyzed using a rigorous CFD model. The model includes the surrounding slotted liner and inner tubing to identify any interactions of the ICD with the surrounding completion. The CFD model has been verified for grid and domain independence and it was applied to a range of flow rates representative of the field condition. In addition, simulations were run for a range of single-phase incompressible fluids with varying viscosities. Using the newly proposed criteria, the ICDs were evaluated and compared. The comparison shows that, of these devices, the diode does the best job of restricting the flow at high flow speeds and low viscosities. At high viscosities, such as in the case of oil, the diode is the least restrictive device. Although the two straight nozzles tested are slightly worse at restricting the flow, they have the lowest erosion potential. Based on this comparison and the proposed criteria, the channel design performs poorly. At low viscosities it does not sufficiently restrict the flow, and at high viscosities it overly restricts the production of oil. It also has a high erosion potential, because of the steep entrance angle. In this work, a new set of quantifiable criteria are defined and assessed that allow multiple aspects of different ICD designs to be compared simultaneously. Overall, these three criteria give a highly sensitive, quantitative means of comparing ICD designs. With these three criteria together, a more comprehensive comparison can be made in support of selection and improvement of ICDs.
L. Li, University of Alberta; C.F. Lange, University of Alberta; Y. Ma, Univeristy of Alberta. Multi-view feature modelling provides a specific view for each phase in product development. The analysis view should be fully integrated with CAD models in a multi-view product development environment for simulation-based design. In the development of fluid flow products, CFD (Computational Fluid Dynamics) is increasingly used as an advanced support. However, the successful application of CFD requires special knowledge and rich experience, which is a barrier for the conversion from the design view to the analysis view, and the maintenance of information consistency. Several approaches to multiple feature views have been proposed, such as design by features, feature recognition and feature conversion. In one-way feature conversion, features in a specific view are usually derived from the original design view [4]. Bronsvoort and Noort put forward a multiple-way approach which enables a designer to modify the product model from an arbitrary view. In this paper, the CAE interface protocol is used to convert the features in the design view into the CAE boundary features in the analysis view. Based on the physical knowledge, an expert system is established to further process those features and generate a robust simulation model with the help of fluid physics features and dynamic physics features in the analysis view. View Publication
H. Soltani, University of Alberta; L. Zhong, University of Alberta; D. Nobes, University of Alberta. The passage of air bubbles and oil droplets with net co-flow through a vertical straight rectangular flow channel is investigated experimentally and analytically in this research. A flow channel, varying from 22 mm × 5.84 mm to 3 mm × 5.84 mm (width × thickness) cross-sectional geometry was used in the present experimental investigation. This flow channel allows the passage of bubbles and oil droplets from a region through two parallel plates into a confined rectangular region. In the rising bubble experiments, the characteristics of bubbles varied from 0.75 mm to 3.2 mm diameter rising in a water/glycerol mixture were captured. Results show that in the parallel plates region, the flow can be described by the available theory. In this region, as bubbles become larger in size, their terminal velocity increase due to the relatively higher buoyancy force (comparing to the smaller bubbles) on the bubbles in the flow and negligible effect of confining geometry on bubble terminal velocity. On entering the rectangular confinement, however, bubbles of relatively large size compared to the rectangular confinement geometry, decelerate to a much lower terminal velocity due to the drag force expressed by the confining walls. A semi-empirical model for determining the bubble terminal velocity in a rectangular geometry is developed to predict this motion. The flow around air bubbles have been investigated using two image processing approaches of PIV and PTV. Because the PTV data was cluttered and the fluid velocity profile cannot be seen, the PTV sparse field was interpolated onto a regular gird. Quantitatively, it was shown that the PIV and interpolated PTV processing results were approximately the same. A theoretical model for streamlines in the flow surrounding bubbles has been developed to be compared against the experimental data. Results showed that the tangential fluid velocity at the bubbles interface matched well with the developed analytical mode. Flow of an oil droplet in a net fluid co-flow through a vertical rectangular confinement is investigated in this study. Five fluid fluxes were provided to flow along with the droplets through the rectangular confinement and two droplet sizes at each fluid flux were chosen to be investigated. Transparent canola oil was used as the oil droplet and glycerol was chosen to be the working fluid as it allowed the refractive index of both phases to be matched. Similar to the rising bubble experiment, to quantify the velocity vector field, PIV and PTV processing approaches were employed to analyze the displacement of tracer particles in the oil droplet and surrounding fluid. An interesting observation was two counter-rotating vortices on either sides of the rising droplet, because of the mechanical force exerted on the droplet from the surrounding fluid and the confining walls. Results showed that as the fluid flux increased, the counter-rotating vortices became stronger, because of increase in the momentum on the rising droplet. The fluid velocity at the rectangular confinement centerline has been derived from both PIV and PTV processing. It was shown that the fluid velocity at centerline is the maximum magnitude at the droplet center and farther from the droplet center, the centerline velocity decreases. View Publication
Air bubbles, liquid droplets and solid particles are highly ranked in terms of fundamental importance. Dispersion of air bubbles and oil droplets in a liquid medium leads to mass transfer, which is the basis of fluid-fluid extraction [1]. Bubbles rising in a fluid medium are also important and practical to many chemical and food processes for improving mass and heat transfer [2]. Terminal velocity and shape regime of a rising bubble depend on fluid medium characteristics such as fluid impurity and flow rate, and the dispersed phase’s shape and size [2]. Some researchers have predicted the terminal velocity of bubble rising in a bounded medium [2] and the velocity field around a single bubble using imaging techniques such as particle image velocimetry (PIV) [3]. However, little information on the flow around bubbles and their rising velocity as passing through rectangular orifices appears in the literature. In this study, the flow of air in a vertical narrow straight slot in the opposite direction of gravity are imaged in a shadowgraph configuration. These images can be processed to calculate size and rising velocity of bubbles passing through the mini-slot. To quantify the velocity field in the fluid surrounding the bubble analysis of seed particles can be undertaken using PIV and particle tracking velocimetry (PTV). This paper will report how this analysis can be undertaken and the effect of the different processing methods has on other derived parameters such as vorticity and fluid shear. View Publication
Steam assisted gravity drainage (SAGD) is of the methods used to recover heavy oils from oilsand reservoir formation. The production of heavy oil also results in the transport of other fluids (steam, brine) generally in emulsions and the production of sand, all of which may have different surface charges. Such a mixture travels through slotted liners which are used as sand control devices. The movement of the charged particles results in electro-osmosis and electro-phoresis phenomena which may intensify the particles buildup on the corroded surface of the slots. This results in fouling, plugging of the slots and decrease in bitumen production which may cause well failure in the life time of SAGD processes. Knowledge of the electro-hydrodynamics and the migration of sands through slots in the SAGD wells are important to understand the failure mechanisms. The movement of carried charged particles through slots in SAGD wells can be due to pressure driven forces and electrokinematicaly phenomena. In this study, a unique flow cell with the same surface characteristics of the slots is designed to model the slots in a SAGD well. The aim of this study is to determine the velocity field of particles through slots using particle image velocimetry method and calculate the pressure across the slot using a numerical approach. This data will be used to validate models that describe the combination of pressure and electro-drive flows in long aspect ratio slots. View Publication
S. Ansari, University of Alberta. Steam assisted gravity drainage (SAGD) is an enhanced oil recovery technology for producing bitumen and heavy crude oil. In this process, high viscosity and possibly non-Newtonian fluids flow from porous media into a production well via slots that have been machined into a production pipe. The dimensions of these narrow slots are adjusted to provide sand control and prevent solids from being produced. The SAGD process also suffers from plugging and scaling of these slotted liners. There is therefore strong interest in understanding the flow through these micro scale orifices for non-Newtonian fluids that potentially carry solids for both design of the slot for production as well as addressing failure modes. In this study, particle image velocimetry (PIV) was used to study the effect of variation in the geometry on the development of the velocity profile and subsequently the change in the upstream and downstream flow. The velocity field of Newtonian and non-Newtonian fluids through micro scale orifices is also investigated with this method. Water as a Newtonian fluid was used to generate a base case velocity field. Water mixed with 0.2 wt. % polyacrylamide was used as non-Newtonian fluid to understand the effects of changing viscosity across the flow field. For Newtonian fluid a jet was observe at the downstream of the straight micro-orifice while in the case of non-Newtonian fluid the shear thinning property of fluid suppressed the jet formation. As it was expected for the Newtonian fluid a parabolic profile was found for water and power-law velocity profile was observed for polyacrylamide solution. The obtained result from this study will be helpful for finding the optimum geometry for channels to decrease scaling and plugging of the slots in the SAGD Process. View Publication
The velocity profile across a conduit is vital information for a number of applications. Here, the development of the velocity profile from the entrance regime to the developed regime was studied in detail specifically in for the case of a non-Newtonian fluid. The velocity profile across a rectangular mini-channel was measured using particle image velocimetry (PIV). The channels were made from poly methyl methacrylate (PMMA) and were fabricated from solid models using a commercial laser cutter. Polyacrylamide solution with shear-dependent viscosity (shear-thinning) was used as the working fluid and the fluid with different shear-dependent exponents (shear-thinning rate) was used to examine the change in the velocity profile. The instantaneous velocity profiles for different Reynolds numbers (Re) were compared with the theoretically derived velocity profiles to comment on the accuracy of the adopted measurement technique. Rheological measurements using a rheometer were preformed to obtain the power law for the non-Newtonian fluids at room temperature. In the case of non-Newtonian fluids, the instantaneous velocity profiles were acquired with the same flow rate as used for the Newtonian fluid case. It is evident that the velocity profile has strong dependency on fluid viscosity and the shear thinning characteristics. The aim of this work was to apply the PIV technique to obtain velocity profiles, which will be curve-fitted to obtain the rheological parameters in-situ. In this study it was observed that the rheological properties obtained from the velocity profile closely matches with the measurements performed using the rheometer. This method is a paradigm shift for the measurement of rheological properties of complex liquids which are difficult to characterize using conventional rheological measurement tools. View Publication
Steam assisted gravity drainage (SAGD) is widely used to recover bitumen from oilsand reservoirs in northern America. One of the common failure in SAGD process is scaling in slots located on the SAGD wells due to flow of the mixture of bitumen and sand into a well. This mixture usually carries dissolved ions and charged sands. As a result, electro-kinetic phenomena is expected to be of the main scaling mechanisms. The aim of the current study is to experimentally study electrohydrodynamics of the scaling formation in the slot. A transparent flow cell with an inserted metal coupon is to designed simulate the geometry of the slots in SAGD operation. Electric field is applied across the slot to intensify the effect of electro-kinetic forces. The electro-driven flows through the slot are visualized using shadowgraphic PIV. Based on the results, migration and buildup of particles are observed on the surface of the slot and the layer of particles is formed. The thickness of this layer decreases as the viscosity of the fluid increases. Migration of particles in the carrying fluid results in particles accumulation that may represent the scaling of sand particles. The result of this study is helpful for optimizing the geometry of slots to control the thickness of the scale formation and the life time of SAGD wells.
Steam assisted gravity drainage (SAGD) is a process used to recover bitumen that is buried deep below ground, and cannot be accessed through conventional methods. In the SAGD process, two wells are drilled into the ground and one is utilized to inject steam and the other to recover bitumen. Sand control devices are implemented to reduce the sand production. Slotted liners are widely used in the sand control systems. These liners are prone to failure due to fouling, corrosion, and scale formation. The objective of this study is to understand and visualize how the scale formation affects the pressure drop across one slot. The scale formation in a straight channel was simulated by changing the entrance geometry of the channel. Particle image velocimetry (PIV) shadowgraph was used to visualize and understand how the flow affects such failure mechanism. The three different entrance geometry were studied and it was found that changing the entrance geometry also changes the streamlines, affecting the loss coefficient and hence affecting the pressure drop encountered by the fluid. Understanding how the scale formation occurs in the SAGD process, helps better the design of the slotted liners to expand the lifespan of such wells and preserve the production rate at ideal levels.
Steam-assisted gravity drainage (SAGD) is a common technique used for oil sands recovery in Alberta. One of the major goals of any SAGD operation is to extract bitumen with minimal sand production. The slotted liner is a common sand control device that is used in SAGD operations. It contains multiple slots longitudinally and radially throughout the pipeline. The objective of this research is to develop an online system to measure the size and falling velocity of the sand produced through the slot using particle sizing velocimetry (PSV). The results presented in this paper serves as the first phase of the ultimate goal of the research, whereby the PSV experimental set-up was also to measure the characteristics of known particle sizes.
One method to recover bitumen from oil sands is steam assisted gravity drainage (SAGD). In the SAGD process, well completion devices known as slotted liners are commonly used for sand control (Xie et al., 2007). These devices handle varying flowrates through them during the duration of the SAGD process. As a focus for this study, it is of interest to characterize the jet exiting a nozzle while under conditions similar to those found in the SAGD process. Through the use of a forward forward-scattering stereoscopic particle image velocimetry (PIV) system, the velocity of a jet exiting a nozzle with an aspect ratio of 250 was measured for Mach numbers of 0.25, 0.3, and 0.35. It is apparent that the exiting jet has three distinct flow asymmetries: near one of the nozzle edges at the nozzle exit, near the x-plane, and about the z-plane. It also appears that the jet dissipates more quickly as the Mach number increases. From these observations, it is clear that both geometrical defects from nozzle assembly, and particle evaporation due to an increase in flowrate result in large flow gradients and also lead to losses in the information of the true development of the jet structure.
The objective of this study is to identify the flow behaviour of a low Reynolds number jet flow exiting a high aspect ratio rectangular slot using a scanning two-dimensional particle image velocimetry (PIV) with the aim to develop a three-dimensional understanding of the flow. In this method, the flow volume is scanned by a light sheet and images of the illuminated planes are captured by a camera. Since the flow is steady, the two-dimensional images of each slice are individually processed to velocity vector fields. So, in-plane components of the velocity within the volume are measured. Then, the out-of-plane component of the velocity is calculated from the continuity equation.
A new method for determining the refractive index of a suspension is developed. The method is based on comparing the images resulted from a light passes through a mixture of particles and a fluid. Ideally, for a refractive index matched between the suspension and fluid, light passes through the medium with no refraction. In practice, mismatching the refractive indices between the fluid and the suspension changes the light direction. This can result in leaving a shadow of the suspension on a camera. Changing the reactive index of the fluid results in different shadow images. Comparing these images with a reference image (that represents the ideal situation) and obtaining the most similar image to the reference image, gives the closest refractive index of fluid to the suspension. Using this approach, the refractive index of the suspension can be approximated without using a laser light. Such approach is safe and simple to be used in any lab.
The passage of air bubbles along with net co-flow (20 ml/hr) through a vertical straight slot with (3 mm × 5.842 mm, width × thickness) inside a rectangular flow channel was investigated in this study. Bubble sizes were varied from bubbles of diameter smaller than the slot width up to relatively larger diameters and bubble acceleration and/or deceleration at entering and exiting the mini-slot was investigated. Particle Shadow Velocimetry (PSV) was used to quantify air bubble characteristics and behaviour on entering and exiting the mini-slot. For the working fluid, which flowed with a bubble in the flow cell, a water/glycerol mixture was used and the dynamic viscosity was calculated using water/glycerol reference tables. As bubbles become larger and closer in diameter to the slot width, confinement becomes an important factor as a resisting force on bubble passage is developed. Results show that, in the region of before and after the slot, bubbles of bigger sizes had higher rise velocity due to higher buoyancy force. As entering the slot, however, bubbles of relatively bigger diameter decelerated due to confining wall drag force.
The work presented in this paper focuses on determining the parameter, 𝜙, that describes the flow convergence caused by the rectangular orifice. An analytical model based on the one-dimensional Navier-Stokes equation is developed. Experimental measurement of the pressure drop across rectangular orifices of different aspect ratio, 𝐴𝑅, are used to devise a model for the flow convergence using non-linear least square fitting.
Y. Yusuf, University of Alberta; S Ansari, University of Alberta; M. Bayans, University of Alberta; R. Sabbagh, University of Alberta; M. El Hassan, University of Alberta; D.S. Nobes, University of Alberta. Motivated by the use of slotted liners in the production of bitumen steam assisted gravity drainage, this paper aims at quantifying the convergence phenomenon experienced by the flow as it enters these long aspect ratio apertures (slots) found on the lateral surface of these liners. A 2D measurement technique - particle shadowgraph velocimetry – was used to visualize the flow fields through rectangular channels manufactured to represent SAGD slots. The effects of the channel Reynolds number (Re = 0.1 to 10), and the width of the flow channel before the slot, on the curvature of the streamlines were studied. Results showed that the curvature in streamlines increased as the flow Reynolds number increased whereas an increase in wall distance led to lower curvature of streamlines. View Publication
H. Soltani, Univeristy of Alberta; R. Azadi, University of Alberta; A. Baldygin, University of Alberta; S. Ansari, University of Alberta; D.S. Nobes, University of Alberta. Flow of an oil droplet in a net fluid co-flow through a vertical rectangular confinement is investigated in this study. Oil-in-oil emulsion can lead to coalescence of fine droplets forming into relatively larger droplets that need to be investigated individually. Emulsion can occur in a variety of industrial processes, where the effect of both body forces and surface forces should be considered. Here, the passage of a single oil droplet through a 3 mm × 5.84 mm (width × thickness) rectangular confinement, where the oil droplet diameter is relatively larger than the confinement width (3 mm), is monitored. A particle shadow velocimetry (PSV) system is employed as the optical measurement technique to capture the fluid flow motion inside and around the oil droplet as rising through the confinement. Transparent canola oil was used as the oil droplet and glycerol was chosen as the working fluid, allowing matching of the refractive index of both phases. The velocity field around and inside oil droplets were determined using a particle image velocimetry (PIV). Near the confining walls, PIV interrogation windows can potentially overlap with the wall or different flow features. In order to increase the resolution of the measurement, particle tracking velocimetry (PTV) image processing was assessed here. In PTV processing, since the particles are tracked individually (no interrogation window), sparse data sets are generated. To allow comparison of the two approaches, the PTV sparse data field was interpolated onto a regular grid and compared to PIV. While good general agreement was achieved, the spatial averaging of PIV resulted in a smoother vector field while noise was evident in the PTV as a result of the limits of particle detection inherent to the approach. View Publication
M.A. Kazemi, University of Alberta; R. Sabbagh, RGL Reservoir Inc; L. Kinsale, University of Alberta; H. Soltani, University of Alberta; D.S. Nobes, University of Alberta. This paper presents a particle tracking velocimetry (PTV) system for measuring the flow within a porous medium at pore scales. Refractive index matching allows full optical access to the inner pores of the porous medium. By analyzing the images taken from a single camera, the in-plane components of the velocity at different locations in the depth were obtained from the PTV algorithm. By assuming the concept of continuity of an incompressible liquid, the gradients of the in-plane components were used to calculate the out-of-plane component of the velocity in each plane. The approach developed here has the potential to be implemented in measuring the flow field in any other application to obtain the out-of-plane component of the velocity. View Publication
S. Ansari, University of Alberta; M. Bayan, Univeristy of Alberta; F. Rasimarzabadi, University of Alberta; D.S. Nobes, University of Alberta. A Tesla-diode valve allows restricted flow in one direction with the use of no moving parts and has many potential applications in different industrial situations. Understanding the flow through the valve is important for characterizing the performance of the device. In the present study, the effect of Newtonian and non-Newtonian nature of the fluid on the flow through a Tesla-diode valve is studied. Particle shadowgraph velocimetry (PSV) is used to visualize the velocity field. The results of this study showed that, as opposed to what is reported in the literature, a Newtonian fluid flow exiting from one stage of the valve, exhibits an unsteady behavior. The formation of vortices was observed, fluctuating in characteristics and moved toward the exit of the diode. The flow of the non-Newtonian fluid, however, showed stable flow within the Tesla-diode valve geometry at the same Reynolds number. View Publication
L. Kinsale, University of Alberta; D.S. Nobes, University of Alberta. Steam-assisted gravity drainage (SAGD) is a technique used for oil sand recovery in Alberta. Oil sand is a composition of sand, clay, water and bitumen. A slotted liner is used in SAGD operations to allow multiple phases flows to be produced, passing the flow through narrow slots throughout the length and circumference of the liner, which minimizes sand production. The objective of this research is to examine the phenomena that occur in the near-slot region to investigate the influence of flow characteristics on slot failure. A particle shadowgraph velocimetry (PSV) experimental set-up in conjunction with image processing techniques were used to investigate the effect of the presence of porous media on the flow field and the build-up of particles in the near-slot region. The experiments were performed with a single slot under two conditions, the flow into a single straight slot and a slot with an inlet condition aimed to simulate porous media. This study shows that particle shape at the micro scale and the presence of porous media affects the transport of particles in the near-slot region. View Publication
R. Azadi, Univeristy of Alberta; H. Soltani, University of Alberta; R. Sabbagh, RGL Reservoir Inc; D.S. Nobes, University of Alberta. The motion of single bubbles in a net co-flow rising through a vertical rectangular confinement is experimentally and numerically investigated in this paper. A flow channel, varying from 22 mm × 5.84 mm to 3 mm × 5.84 mm (width × thickness) cross-sectional geometry was used in the present experimental investigation. The bubble sizes ranged from with 0.91 mm to 2.85 mm and the bubble motion was captured using a particle shadow velocimetry (PSV) measurement technique. A water/glycerol solution was used to control the continuous phase viscosity, while providing a fluid co-flow along with the flow of bubbles. Images were collected using a high-resolution, high-speed camera in a back illuminated configuration. The collected images from the experiments were processed using two image processing approaches of particle recognition to derive the bubble characteristics (size and rising velocity etc.) and particle image velocimetry (PIV) to determine the velocity vector map around the rising bubble, respectively. In addition, a coupled volume-of-fluid and level set method (VOSET) was used to numerically capture the interface of bubbles and compute the terminal velocity of them. It is shown that there is a good agreement between numerical and experimental results. Based on the results, for bubbles with diameters more than 1.56 mm, increasing the bubble diameter decreases its terminal velocity. View Publication
S. Ansari, University of Alberta; R. Sabbagh, RGL Reservoir Inc; H. Soltani, University of Alberta; D.S. Nobes, University of Alberta. Steam assisted gravity drainage (SAGD) is an enhanced recovery method used to recover high viscous crude bitumen from oilsand reservoirs. In this process emulsions are generated in the reservoir through the formation of water bubbles due to interfacial phenomena or heat transfer between the two phases. The presence of water bubbles in the produced oil intensifies the effects of the emulsion flow on the pressure drop and the flow through the surrounding porous medium. The aim of this research is to investigate the deformation of a bubble in an oil flow through a 2D porous medium. The deformation of the bubble is visualized using a micro shadowgraph particle image velocimetry (μSPIV) method. The results are further analyzed to investigate the pressure drop introduced to the continuous phase by the pore in the presence of a deformed bubble. View Publication
Micro shadowgraph particle image velocimetry (µ-SPIV) has found several applications in multiphase flows including measuring velocity distributions at the pore-scale of a porous medium. This can be applied to obtain further information about the fluid flow, such as the pressure field in a porous medium. The pressure distribution resulting from a multi-phase flow through porous media is an important parameter that can be used to determine properties of a reservoir and infer information on the flow/fluid characteristics in oil recovery methods. Determination of the pore-scale pressure distribution in a flow field using a direct measurement technique is a challenging task. However, results from measurement of the velocity field can be combined with the suitable theoretical model of the system to calculate the pressure field. In this study, the development of an approach to investigate a multi-phase flow through a pore geometry is described. Velocity measurements for both continuous and disperse phases were combined with Poisson's equation to determine the pressure distribution. The applicability of the presented approach is highlighted by comparing the results with those from pressure drop calculations solely based image on analysis.
The objective of this research is to study the effect of flow rate and hence Reynolds number on the flow field of the sand control aperture, a high aspect ratio rectangular slot, using stereo particle image velocimetry (stereoPIV) with the aim to develop a three-dimensional understanding of the flow. As a simplified model, the experiments were conducted on a single full scale constructed slot using water and air as the working fluids. A rectangular slot with length to width ratio of 75 is studied at different flow rates resulting in Reynolds numbers ranging from very low to high ones based on hydraulic diameter of the slot for two different working fluids. View Publication
The performance of steam assistant gravity drainage (SAGD) heavy oil and bitumen extraction is highly affected by the flow performance in pores adjacent to sand control devices. The fluid (liquid, gas) and solid particles pass along paths inside the porous media around the production or injection pipes. Fines that are passing through the pores may plug a path and change the flow condition at the pore scale and hence the pressure drop. To understand mechanisms of fine transport that affect the oil production, a physical interpretation of the flow inside the pores is useful. Such a flow is studied here undertaking several flow experiments at the bench scale. Refractive index matching is a method for velocimetry and flow visualization within a porous medium. A new approach for matching the refractive indices of a fluid and a medium is explained in this research. The particle (solid, liquid or gas) transport phenomenon is investigated by shadowgraphy particle image velocimetry (shadowPIV) technique for flows at different flow rates passing through a channel. Velocity profiles and streamlines are obtained from shadowPIV at different cross sections of the porous media to cover a volume. The processed results are used to determine the potential clogging points and paths in the porous medium and the channel.
Capillary effect is observed in many applications where a liquid flows through a narrow channel. Some industrial flows such as flow in porous media in steam assisted gravity drainage (SAGD) oil production can be modeled using the capillary concept and assuming straight capillary channels. Although the capillary effect has been studied in the literature, velocimetry in capillaries is still an ongoing research particularly for the non-Newtonian liquids. The assumptions of the Newtonian fluids cannot be applied for the non-Newtonian viscous liquids in capillaries. Depend on the capillary and liquid condition, surface forces or viscous forces may become the major force for describing the capillary phenomena or otherwise both forces have a comparable order of magnitude. This study investigates the effect of liquid rheology and the capillary properties (such as capillary size, cross sectional geometry and wetting conditions) on the velocity profiles of a liquid flow in a capillary tube. A unique experimental setup is designed for such a flow study considering the fact liquid flows fast in the micro tubes. Using an imaging system and particle image velocimetry (PIV), velocity profiles are obtained in the tubes. The effect of capillary and liquids are studied at different times from when the liquid starts rising in the tube and after the developed regime is observed. The information from velocimetry is then applied to develop a theoretical model that explains the capillary transport for no-Newtonian liquids. View Publication
In many industrial applications, such as food and chemical processes, rising air bubbles are used in practical applications to improve heat and mass transfer. As a bubble rises through a liquid medium, different surface forces and body forces would act on the bubbles from the surrounding. In this study, the passages of air bubbles of different sizes thought a vertical straight slot inside a flow channel are investigated. Bubble sizes are varied from bubbles of smaller diameter than slot width up to relatively larger diameters. Shadow image velocimetry is used to quantify the rising velocity and size of bubbles as they pass through a minislot. For the working fluid which flows along with bubbles in a flow cell, a water/glycerol mixture is used to have a desired viscosity of approximately 0.4 Pa.s. The acceleration and/or deceleration of bubbles as they enter and exit the mini-slot are investigated in this study. A theoretical correlation developed in the literature for rising bubbles through circular tubes is modified and validated with the current experimental results. Results show that bubbles of relatively closer diameter to the slot width will decelerate on passing through the mini-slot due to the confining wall drag force. View Publication
Three different media are present in the complete flow domain through which bitumen flows into the production well of the steam assisted gravity drainage (SAGD) process. These are flow through the formation, slotted liner, and the annulus. The conditions in SAGD significantly differ from classical problems found in the literature to allow direct application of generic models for flow characteristics such as pressure loss. Each of the flow media in the SAGD flow domain contribute to the pressure loss characteristics of the system through their respective effect on their individual loss coefficients. This study uses experimental investigation of the flow through rectangular orifices (similar to the slots on SAGD slotted liners) at full scale and in the presence of porous media at the inlet section. Experiments in an open slot flow domain (rectangular orifice without porous media) are to be conducted first seeking for a semi-empirical model to describe the flow convergence phenomenon and pressure loss characteristics. Experiments in the coupled flow domain (with porous media at the inlet section) will proceed to develop a comprehensive pressure loss and flow convergence model. It is proposed that the results from open slot experiments are used to compare with experimental measurements in the coupled domain. View Publication
D.S. Nobes, University of Alberta; R. Sabbagh, RGL Reservoir Inc; L. Hasanovich; A. Baldygin, University of Alberta; P.R. Waghmare, University of Alberta. The capillary filling process is significantly important to study for numerous applications such as the under filling of the material in electronic packaging or liquid hydrocarbons seepage through porous structure. The approximation of the fluid being Newtonian, i.e., linear relationship between the shear stress and deformation rate cannot be justified in cases where the extent of non-Newtonian behavior of liquid governs the surface driven transport, i.e., capillarity action. In this study, the capillary action of a non-Newtonian fluid is not only analyzed, but also the modified generalized theoretical analysis for the capillary transport is proposed. The commonly observed three regimes: surface forces dominant (travelling air-liquid interface), developing flow (viscous force dominant), and developed regimes (interfacial, inertial and viscous forces are comparable) are identified. The velocity field along each regime is quantified with Newtonian and non-Newtonian fluid in square shaped vertically oriented channel. Theoretical understanding of capillary imbibition process, particularly in the case of Newtonian fluids, is relied on simplified assumption of a fully developed velocity profile which has been revisited for developing a modified theory for the capillary transport of non-Newtonian fluids. Furthermore, the development of the velocity profile from the entrance regime to the developed regime, for different power law fluids, is also investigated theoretically and experimentally. View Publication
H. Soltani, University of Alberta; J. Hadfield, University of Alberta; M. Redmond; D.S. Nobes, University of Alberta. The passage of oil droplets through a vertical mini-slot were investigated in this study. Oil-in-water emulsion can undergo coalescence of finer oil droplets forming droplets of a size that need to be considered individually. This occurs in a number of industrial processes and has important consequences at a scale where both body and surfaces forces are relevant. In the study, two droplet diameters of smaller than the slot width and a relatively larger diameter where the oil droplet can interact directly with the slot wall were generated. To monitor fluid motion, a particle shadow velocimetry (PSV) imaging technique was used to study fluid flow motion inside and around a single oil droplet rising in a net co-flow. The droplet was a transparent canola oil and the surrounding working fluid was glycerol, adjusted to allow a matching of refractive index between the two fluids. Particles seeded in both fluids were observed with the PSV system allowing the capture of the velocity field both within the droplet and in the surrounds. The effect of droplet size on the droplet internal circulation was observed. Part of the study was related the potential generation of flow structures, such as von Karman vortex shedding already observed in rising droplets in infinite reservoirs and their interaction with the mini-channel. Results show that two counter-rotating vortices exist inside the droplets as they pass through slot. The vorticity map analysis shows that the droplet of relatively larger size has a stronger internal circulation View Publication
J. Hadfield, University of Alberta; D.S. Nobes, University of Alberta. Focused plenoptic imaging is a measurement technique that can perform time-resolved 3D tracking of a particle-seeded fluid. The technique makes use of a single camera equipped with a microlens array, allowing capture of the complete light field. It has the advantage of being simple to set up compared to most other 3D techniques, requiring only a single optical view of the experiment. There are a number of challenges with implementing this technique. The small viewing angle available to this single-camera approach results in difficulty accurately calculating the depths of particles in the fluid. Techniques for addressing this limitation are being investigated. In particular, time-resolved 3D particle tracking has been implemented. Curve fitting along individual particle tracks is used herein to time-average the noise inherent in the depth estimations, with some success. This technique has been tested on the simple case of a steady vortex generated in a vortex chamber. The camera’s viewpoint was parallel to the axis of the vortex to maximize the amount of out-of- plane motion that must be resolved by the imaging technique. Overall, this study indicates that implementing focused plenoptic imaging and time-resolved 3DPTV to detect fluid motion may be a viable method for interrogating the 3D motion of a fluid using a single camera. View Publication
Y.A. Yusuf, University of Alberta; A. Baldygin, University of Alberta; R. Sabbagh, University of Alberta; M. Leitch, RGL Reservoir Inc; P.R. Waghmare, University of Alberta; D.S. Nobes, University of Alberta. In steam assisted gravity drainage (SAGD), bitumen flows through slots whose width is selected based on the particle size of the formation sand to prevent sand production. These slots are susceptible to several failure mechanisms such as plugging, scaling, and fouling. Given the flow optimization that should also be achieved, understanding the phenomenon of flow through these slots is essential. This coupled problem of sand control and flow optimization can be solved if only effects of the slot properties are known and described comprehensively. This study investigates the significance of longer slots in achieving desired flow conditions. The effects of aspect ratio (the ratio of the orifice axial length to the aperture size) of a rectangular orifice on the flow of a highly viscous fluid (dynamic viscosity, µ = 110 mPa.s at 45 ℃) at low Reynolds numbers (Re < 1) is studied. The rectangular shape is selected to represent the slots in slotted liners well completions that are used in SAGD applications. Experiments are performed using different size orifices made on coupons and are located inside a pipe. Aspect ratios (AR) within the range of 1 ≤ AR ≤ 75 are used at different flow rates while keeping Reynolds numbers constant. The results show that increasing aspect ratio leads to increase in both static and non-dimensional pressure drops. The wide range of aspect ratio covered is a unique aspect of the present study when compared to the literature that gave the same definition to the parameter. View Publication
Rise of single bubbles in a free fluid medium has been extensively studied. In this study, the passage of air bubbles of different sizes through narrow straight slots (rectangular orifices) was investigated. The slot dimensions were chosen to be in a range used for other studies in similar cases. Bubble sizes were varied from bubbles of smaller diameter than slot width up to relatively larger diameter. Particle shadow velocimetry (PSV) was used to investigate flow field around single bubbles as they pass through a mini-slot as well as measure bubble size and velocity. As the working fluid which flows along with a bubble in the flow cell, a water/glycerol mixture was used and viscosity and density were calculated using water/glycerol reference tables. As bubbles become larger and closer in diameter to the slot width, confinement should be taken into consideration as a resisting force on bubble passage. Results show that as bubble size increases the rising velocity data sees an upward trend up to a specific diameter. There is a downward trend of bubble rising velocity due to wall effects (confinement). Reynolds number analysis for bubbles show that the range is below what is essential to generate recirculation or a von Karman vortex behind passing bubbles. Results show that all bubble sizes decelerate as they enter the slot and they accelerate again after exiting. In the regions before and after the slot, bubbles of bigger sizes had higher rise velocity due to higher buoyancy force. However, rising velocity had a downward trend inside the slot for bubbles bigger than a certain diameter due to confinement. The vorticity map analysis showed that smaller bubble developed lower a value of vorticity in comparison to the large bubbles. This is because in a system of rising bubble for smaller bubbles the pressure difference between front and rear of the bubble is lower. View Publication
S. Ansari, University of Alberta; R. Sabbagh, University of Alberta; F. Rasimarzabadi, University of Alberta; M. Leitch, RGL Reservoir Inc; P.R. Waghmare, University of Alberta; D.S. Nobes, University of Alberta. Steam assisted gravity drainage (SAGD) is an oil recovery technology where the mixture of bitumen and sand flow into a production well through slots (Dh ~ 1 mm) drilled on a pipe located in the well. Study of the flow passing through these slots is critical to identify and develop understanding of failing mechanisms in SAGD processes such as plugging, scaling, and fouling of the slots. In SAGD process, where the electrolytic fluids are present in the flow of bitumen into the production well, it is expected that the electro-kinetic phenomena play an important role in the failure mechanisms of slots. The aim of this study is to experimentally identify the effect of electro-kinetic properties of particles on the fouling in a laminar flow through mini channels. A flow cell is made from PMMA acrylic sheets for the experiments. Two electrodes are attached to channel walls to apply the electric field that is generated using an external power supply. Particle image velocimetry (PIV) is used to study the velocity field and the deposition of particles on the channel walls. To remove the electro-osmotic effects in the flow, distilled water is used as a carrier liquid. The results from this study is expected to describe the migration of particles in laminar flow through mini-channels and its contribution in fouling mechanism in SAGD wells View Publication
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