Performance and mechanisms of enhanced oil recovery via CO<sub>2</sub> assisted steam flooding technique in high heterogeneity heavy oil reservoir: PVT and 3D experimental studies
Wanfen Pu, Hao Gao, Yibo Li, Qiang Luo
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.HighlightsCO2 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.