Dynamic Gas Separation Integrated Into SAGD for Improved ESP Performance

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 230260, “Introduction of Dynamic Gas Separation to SAGD,” by Shadi Gabasa, SPE, SLB, and Rejish Joseph, SPE, Suncor Energy. The paper has not been peer-reviewed. _ Gas production in steam-assisted gravity drainage (SAGD) operations presents significant challenges, including reduced production rates, shortened electrical submersible pump (ESP) run life, and unstable production. The complete paper demonstrates the effectiveness of integrating dynamic gas separation with existing gas-avoidance methods within the same ESP string to address these issues. The results indicate that the described technology, an upper-tandem gas separator (UT-GS), provides a reliable and efficient solution for gas management in SAGD ESP applications. Introduction Suncor Energy’s Firebag uses in-situ recovery for bitumen extraction, primarily through the SAGD process. At the time of writing, this operation achieves a production rate of over 230,000 bbl of bitumen per day. Within the upstream segment, artificial lift is facilitated by more than 400 ESPs integral to maintaining and enhancing production. One of the principal issues encountered is the reliable operation of ESPs under conditions of elevated gas-volume fraction (GVF) at the pump intake. The management of gas at the ESP intake emerged as a critical factor in achieving and sustaining higher production rates. Changing the Approach to Gas Management A comprehensive evaluation of gas-handling technologies available in the market revealed that the operational performance of gas handlers was inconsistent or inconclusive, with some installations demonstrating effective gas-locking mitigation while others failed to achieve the desired outcomes. Potential factors affecting gas-handler performance include the size and frequency of gas slugs and prevailing fluid-production rates. Underestimation of GVF at the pump intake also has proved a major challenge. Case Study: Signs of Gas Production Exceeding Design Assumptions In a well where the ESP was designed based on gas/oil ratio (GOR) assumptions of standard values, a premature failure was observed because of the presence of produced gas and frequent no-flow events. The ESP was operated for approximately 12 hours on 2 November 2023, with a subsequent restart on 9 November 2023. During these operational periods, the ESP temperature escalated to approximately 270°C. Post-retrieval analysis revealed significant thermal damage, including melted motor-lead-extension (MLE) cable along the pump length and pronounced insulation discoloration (Fig. 1). These findings are indicative of prolonged no-flow or low-flow recirculation conditions while the ESP was running, directly associating operational deadheading with localized overheating of both the pump and adjacent MLE cable. The observed MLE cable degradation suggests that excessive temperatures were reached because of extended ESP operation under no-flow conditions and a higher gas condition at the intake of the pump than had been assumed. Higher GOR: Understanding the Issue A method of reverse calculation using commercial software was employed to predict GOR through diagnostic analysis on running ESPs that exhibited symptoms of gas production. The original design model was used as the baseline for the analysis; actual ESP operating parameters were then incorporated into the same model. Through the design software’s simulation engine (nodal analysis), the software calculated pump-discharge pressure based on two values, intake pressure and tubinghead pressure (THP). Fluid properties greatly influenced the accuracy of these calculations. Dozens of diagnostic studies conducted on wells in different pads at Firebag suggested that the average GOR in these gassy wells was approximately 20 m3/m3.