Abstract In this paper, CO2 assisted steam flooding technique was proposed to further enhance heavy oil recovery after steam flooding. PVT tests and 3D model oil displacing experiment were conducted to investigate enhancing oil recovery (EOR) mechanisms and oil displacing performance. The results indicated that CO2 dissolving in heavy oil could induce oil swelling, reduce oil relative density, and reduce oil viscosity. After steam flooding, 6.8% of sweep efficiency and 8.5% of additional oil recovery were improved by implementing CO2 assisted steam flooding. The study has suggested that CO2 assisted steam flooding is a feasible technique for recovering heavy oil after steam flooding. Highlights CO2 dissolving heavy oil can swell oil volume and reduce oil viscosity dramatically. CO2 alternative steam flooding can improve injection pressure and oil–steam ratio, and reduce steam consumption. Introducing CO2 into steam flooding process can increase both oil displacement efficiency and sweep efficiency, then enhancing oil recovery. CO2 assisted steam flooding is a feasible technique for improving oil recovery in heavy oil reservoir after steam flooding.

中文翻译：

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CO2 辅助蒸汽驱技术在高非均质稠油油藏中提高采收率的性能和机制：PVT 和 3D 实验研究

摘要 本文提出了CO2辅助蒸汽驱技术，以进一步提高蒸汽驱后稠油的采收率。通过PVT测试和3D模型驱油实验，研究了提高采收率（EOR）机制和驱油性能。结果表明，CO2 溶解在稠油中会引起油溶胀，降低油的相对密度，降低油的粘度。蒸汽驱后，通过实施 CO2 辅助蒸汽驱，波及效率提高 6.8%，额外采油率提高 8.5%。研究表明，CO2 辅助蒸汽驱是一种可行的蒸汽驱后稠油采收技术。亮点 CO2 溶解重油可以使油体积膨胀并显着降低油粘度。CO2 替代蒸汽驱可以提高注入压力和油汽比，减少蒸汽消耗。在蒸汽驱过程中引入 CO2 可以提高驱油效率和波及效率，进而提高石油采收率。CO2辅助蒸汽驱是提高蒸汽驱稠油油藏采收率的可行技术。