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Petroleum Science > DOI: https://doi.org/10.1016/j.petsci.2024.11.005
Experimental investigation of hybrid enhanced oil recovery techniques for Ugnu Heavy Oil on Alaska North Slope Open Access
文章信息
作者:Temitope Fred Ogunkunle, Hyun Woong Jang, Asad Hassan Syed, Rian Billings, Lixing Lin, Yin Zhang, Abhijit Dandekar
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引用方式:Temitope Fred Ogunkunle, Hyun Woong Jang, Asad Hassan Syed, Rian Billings, Lixing Lin, Yin Zhang, Abhijit Dandekar, Experimental investigation of hybrid enhanced oil recovery techniques for Ugnu Heavy Oil on Alaska North Slope, Petroleum Science, 2024, https://doi.org/10.1016/j.petsci.2024.11.005.
文章摘要
Abstract: The Alaska North Slope (ANS) is endowed with a substantial reservoir of heavy oil, estimated at 12–18 billion barrels, primarily concentrated within the Ugnu reservoirs. These deposits, situated at depths ranging from 2,000 to 4,000 feet, lie in close proximity to the permafrost and have undergone biodegradation, resulting in in-situ viscosities reaching thousands of centipoise. Following the success in recovering the somewhat less heavy, viscous oils through polymer injection, the deposits in Ugnu Formation are garnering significant interest. Although thermal recovery methods are commonplace for heavy oils, applying these methods on ANS is impractical, given the adjacency to continuous permafrost. Therefore, non-thermal hybrid enhanced oil recovery (cEOR) methods, such as solvent (e.g., CO2) and low salinity water (LSW) based, or LSW and polymer-based techniques, emerge as the primarily feasible options for recovering these vast heavy oil resources. This study experimentally investigates, via systematically carried out fluid property and phase behavior tests and a series of sand-pack coreflood experiments, the potential to enhance the recovery of Ugnu heavy oils. The coreflood experiments reveal the synergistic effect of combining liquid-CO2 with LSW to be the most promising approach in this study as a water alternating gas (WAG) process results in the cumulative recovery factor of 83.5%, doubling the recovery obtained by continuous low salinity waterflood. Additionally, the liquid-CO2-LSW WAG process demonstrated an additional benefit for CO2 storage, with about 25% of the pore volume of the liquid-CO2 injected being sequestered at the end of the injection process. This significant recovery improvement is attributed to a substantial reduction of oil viscosity upon contact with the liquid CO2 during the soaking period, with a reduction of up to 95% of the original oil viscosity. Meanwhile, in-situ emulsion generation was observed in the oil produced from the continuous LSW flooding. This was also evident by the increased differential pressure across the sand-pack compared to that of the liquid-CO2 alternating LSW process. The promising results of this study indicate significant potential for liquid-CO2 alternating LSW injection as an effective cEOR technique for Ugnu heavy oils.
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Keywords: Ugnu; Heavy oil; CO2; Polymer; Low-salinity water; Waterflood