Authors: Mahdi Mahmoudi (RGL Reservoir Management) | Morteza Roostaei (RGL Reservoir Management) | Vahidoddin Fattahpour (RGL Reservoir Management) | Alberto Uzcatequi (RGL Reservoir Management) | Jeff Cyre (RGL Reservoir Management) | Colby Sutton (RGL Reservoir Management) | Brent Fermaniuk (RGL Reservoir Management)

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.

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.

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Authors: Vahidoddin Fattahpour (RGL Reservoir Management) | Mahdi Mahmoudi (RGL Reservoir Management) | Morteza Roostaei (RGL Reservoir Management) | Patrick Nolan (Canadian Natural Resources Limited) | Colby Sutton (RGL Reservoir Management) | Brent Fermaniuk (RGL Reservoir Management)

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.

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.

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Authors: M. Roostaei (University of Alberta) | Y. Guo (University of Alberta) | A. Velayati (University of Alberta) | A. Nouri (University of Alberta) | V. Fattahpour (RGL Reservoir Management) | M. Mahmoudi (RGL Reservoir Management)

Unconsolidated sand was packed on a slotted-liner coupon in large-scale sand retention tests (SRT) and was subjected to several stress conditions, corresponding to the evolving stress conditions during the life cycle of a SAGD producer. Cumulative produced sand at the end of testing was measured as the indicator for sand control performance. Retained permeability was calculated by measuring pressure drops near the liner and was considered as the quantification of the flow performance of the liner. Experimental results indicate the liner performance is significantly affected by the stress induced compaction of the oil sand. The stress results in the sand compaction, leading to a denser sand, hence, a lower porosity and permeability. The lower porosity results in a higher pore-scale flow velocity, which can trigger more fines mobilization, hence, a higher skin buildup. With respect to sanding, the higher stress can stabilize the sand bridges: Increased normal forces between near-slot sand particles result in a higher inter-particle friction, hence, more stable sand bridges and less produced sand. The lower and upper bounds of slot window are governed by plugging and sand production, respectively. Experimental results indicate an upward shift in both the lower and upper bounds at elevated stress conditions.

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Authors: Morteza Roostaei (RGL Reservoir Management) | Omar Kotb (University of Alberta) | Mahdi Mahmoudi (RGL Reservoir Management) | Vahidoddin Fattahpour (RGL Reservoir Management) | Chenxi Wang (University of Alberta) | Alireza Nouri (University of Alberta) | Brent Fermaniuk (RGL Reservoir Management)

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.

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Authors: M. Mahmoudi (RGL Reservoir Management Inc.) | V. Fattahpour (RGL Reservoir Management Inc.) | M. Roostaei (RGL Reservoir Management Inc.) | O. Kotb (University of Alberta) | C. Wang (University of Alberta) | A. Nouri (University of Alberta) | C. Sutton (RGL Reservoir Management Inc.) | B. Fermaniuk (RGL Reservoir Management Inc.)

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.

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Authors: J. D. Montero (University of Alberta) | S. Chissonde (University of Alberta) | O. Kotb (University of Alberta) | C. Wang (University of Alberta) | M. Roostaei (University of Alberta) | A. Nouri (University of Alberta) | M. Mahmoudi (RGL Reservoir Management Inc.) | V. Fattahpour (RGL Reservoir Management 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.

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