Chemical EOR Opportunities in Depleted Reservoirs of Assam Arakan Basin: A Laboratory EOR Approach in Tengakhat Area of Assam

Significant portions of oil in petroleum reservoirs remain unrecovered after the primary and secondary production phases. To address this challenge, chemical Enhanced Oil Recovery (cEOR) techniques such as polymer flooding, alkali–polymer flooding, and alkali–surfactant–polymer (ASP) flooding are es...

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Bibliographic Details
Published in:Energy & fuels 2024-08, Vol.38 (15), p.14052-14063
Main Authors: Dhar, Vishal, Sarma, Kuladip, Hens, Sushovan, Baishya, Debasish, Sarmah, Rajib, Tiwari, Pankaj
Format: Article
Language:English
Subjects:
Traditional Fossil Fuels
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Summary:Significant portions of oil in petroleum reservoirs remain unrecovered after the primary and secondary production phases. To address this challenge, chemical Enhanced Oil Recovery (cEOR) techniques such as polymer flooding, alkali–polymer flooding, and alkali–surfactant–polymer (ASP) flooding are essential to enhance the displacement efficiency. In mature oil fields like Tengakhat in the Assam Arakan Basin, where Oil India Limited operates, maximizing recovery is crucial amidst the declining production from existing reserves and limited new field discoveries. Despite advancements, substantial quantities of oil are left behind in reservoirs post conventional production methods. The literature reveals a critical need for tailored chemical combinations to optimize the recovery, particularly in fields where conventional methods are reaching their operational limits. This study addresses the gap by systematically screening various chemicals and their combinationspolymer, alkali, and surfactantto identify the optimal cEOR strategies for the Tengakhat oil field. The research focuses on enhancing macroscopic and microscopic displacement efficiencies to recover capillary-trapped or water-bypassed oil effectively. The study employs comprehensive screening techniques, including 1H NMR, FTIR, FESEM-EDX, and GC-chromatography, to characterize reservoir fluids and cores. Chemicals are evaluated based on their ability to reduce interfacial tension (IFT), modify wettability, and enhance fluid viscosity. Screening studies determine the best performing chemicals, followed by coreflood experiments to validate their effectiveness in recovering oil from reservoir cores. 0.2 wt % SDS for surfactant, 2 wt % NaOH for alkali, and 2000 ppm XG for polymer were identified as optimal concentrations. ASP flooding demonstrated the highest recovery efficiency, achieving approximately 31% of original oil in place (OOIP) following secondary recovery efforts. This study underscores the effectiveness of ASP flooding in maximizing oil recovery from mature reservoirs like Tengakhat. By leveraging tailored chemical combinations, operators can significantly enhance recovery rates, thereby prolonging the economic viability of existing oil fields and reducing the dependency on imported petroleum resources.
ISSN:0887-0624
1520-5029
DOI:10.1021/acs.energyfuels.4c02092