芳48非均质断块油藏二氧化碳驱油效果研究

CO_2 Flooding of Fang48 Heterogeneous Fault-block Reservoir

为研究芳48断块非均质性对CO2驱油效果的影响,在模拟实际油藏条件下,采用天然岩心进行室内物理模拟实验。结果表明:在相同实验条件下,与均质岩心相比非均质岩心CO2驱最终采收率低16.28个百分点以上,且气体突破快,注入压力高;3种非均质地层中,正韵律地层和层内非均质地层CO2驱油效果较好,反韵律地层最差,且反韵律地层气体突破快、注入压力高;非均质岩心高渗层对最终采收率的贡献率高于97.90%,高渗层的吸气量占99.59%以上,低渗层几乎没有启动。因此,储层非均质性是导致芳48断块CO2开发效果不理想的主要原因。借鉴国内类似油田开发经验,建议结合压裂进行单井CO2吞吐。

In order to identify the effect of reservoir heterogeneity of Fang48 fault-block reservoir on CO2 flooding,natural core samples were used in laboratory physical simulation under actual reservoir conditions. The experiments indicate that comparing to homogeneous core samples,the CO2 flooding of heterogeneous core samples are featured by more rapid gas breakthrough,higher injection pressure and more than 16. 28% lower ultimate recovery factors. In the three heterogeneous experiments,the CO2 flooding performances of positive rhythm reservoir and in-layer heterogeneous reservoir are better than that of reverse rhythm reservoir which is featured by more rapid gas breakthrough and higher injection pressure. High-permeability layer in heterogeneous core sample contributes more than 97. 90% to the ultimate recovery factor and more than 99. 59% to the total gas influx,and the low-permeability layer is almost not produced. Therefore,reservoir heterogeneity is the key factor that results in the poor CO2 flooding performance of Fang48 fault-block. In view of the domestic and similar oilfield development experiences,CO2 soaking with fracturing is suggested for the development of Fang48 fault-block reservoir.