Enhancing ASP Flood Design: Integrating Pilot Learnings, Lab Re-Optimization and Field Analogues Before Commercial Implementation - A Case Study of India

Abstract

Abstract The ASP flooding is a complex technology as experienced from latest field implementations at western onshore basin in ONGC. Although, ASP pilot has been successfully executed in concerned reservoir, few challenges are still present. The present paper proposes to address these challenges before moving for the commercialization. Encouraging laboratory and simulation results lead to ASP pilot with inverted five spot pattern. The pilot shows directional heterogeneity leading to early breakthrough which necessitated Profile Modification and Water Shut off jobs. Active aquifer and low polymer buffer viscosity lead to increase in water cut. Besides, the chemical quality monitoring, supply chain management were the challenges to be addressed before full field expansion. The re-optimization of chemical formulation is also performed in lab to mitigate the detrimental effect of alkali induced scaling and to reutilize the effluent water. Simulation was also revisited with envisaged incremental oil of 6.6% in thirteen years. Lessons learnt during pilot implementation and the experience of a commercial ASP project in an analogous field helped in better formulating development strategy for the present project. To prevent the ground water exploitation and better management of effluent water, the ASP formulation was modified without compromising its performance. The scaling problem as was encountered at surface and subsurface in analogous field lead to reduction in alkali concentration and incorporation of scale inhibitor. For better control of chemical supply chain and quality monitoring, the responsibility matrix was revisited. ASP expansion has been considered in the structurally top part where sand is well developed and well productivity is higher with reduced well spacing. Sensitivity runs showed that incremental oil recovery increases with higher slug size and higher polymer buffer concentration. The ASP injection comprises of 14 inverted 5 spot patterns. The surfactant induced tough emulsion formation is also proactively addressed in the upcoming ASP project. Although ASP process is a complex technology but it has the potential to significantly enhance the field recovery. The technical and managerial challenges faced in pilot and in the running of commercial project helps to take necessary action beforehand. No matter how well prepared a plan may be it is inevitable that it will face challenges and obstacles along the way. However, being agile and timely midcourse correction is the key for success.