稠油油藏CO_(2)辅助蒸汽驱油机理实验研究

Experimental study on mechanism of CO_(2) assisted steam flooding in heavy oil reservoir

为进一步明确稠油油藏CO_(2)辅助蒸汽协同驱油机理,利用亚克力板可视化模型和天然岩心,开展了可视化CO_(2)辅助蒸汽驱油实验,分析了CO_(2)辅助蒸汽驱油过程中二者之间存在的“协同作用”及注入方式对实际驱油效率的影响。结果表明,CO_(2)辅助蒸汽驱具有协同降黏、扩大蒸汽波及系数、启动盲端残余油、破乳等“协同作用”,其中原油综合降黏率达到59.8%,蒸汽波及面积提高了37.44%。对比纯蒸汽驱,CO_(2)辅助驱可使原油采收率大幅上升,其中交替注入蒸汽与CO_(2)采收率为65.7%,比混合注入提高了7.9%,且能够在出口端观测到稳定的泡沫油流。

In order to further clarify the mechanism of steam flooding assisted by CO_(2)in the heavy oil reservoir,its visualization experiments are carried out by the acrylic plate model and natural cores,and their synergy is analyzed.After the mechanism of synergistic displacement is clarified,the core flow experiments are carried out to further analyze the influence of the synergistic effect and the injection mode on the actual displacement efficiency.The results show that CO_(2)assisted steam flooding has the effects of the synergistic viscosity reduction,the expansion of steam sweep efficiency,the availability of residual oil at the blind end,and the demulsification.Among them,the comprehensive viscosity reduction rate of the crude oil is 59.8%,and the steam sweep area is increased by 37.44%.Compared to the flooding by steam alone,after the assitant of CO_(2),the recovery rate increased significantly.The alternate injection of steam and CO_(2)can get a recovery rate of 65.7%,7.9%more than that of mixed injection,and observe the stable foam oil flow at the outlet.