针对特低渗透扶杨油层注水开发中存在的注入难、采出难,水驱开发效果差,采收率低的问题,在榆树林油田树101 井区开展了扶杨油层CO2驱油试验。通过现场试验对CO2驱替状态、开发特征及效果进行了系统评价,结果表明,当试验区注入CO2为0.1 HCPV(烃类占据的孔隙体积)时,通过两次高压物性取样对比,轻质组分含量增加了5.7%,最小混相压力由32.2 MPa 下降至28.6 MPa。试验区存在混相、半混相及非混相3 种驱替状态,混相区域占2/8,半混相占1/8,非混相占5/8。通过研究和矿场实践,形成了不同注气阶段不同类井的CO2驱开发调整技术,试验区采油速度连续4 年保持在1%以上,数值模拟预测最终采收率比水驱高10%以上,试验区取得了显著的开发效果。
Various problems exist in the development of Fuyang extra-low permeability oil layer using water flooding, including injection difficulty, recovery difficulty, low effectiveness, and low recovery rate. To solve these problems, a CO2 flooding test was carried out at Shu101 well block in Daqing Yushulin Oilfield. Systematic evaluation of the displacement state, development characteristics and effects of CO2 flooding was conducted. The results show that when the injection rate of CO2 was 0.1 HCPV, through comparison of high pressure physical properties of two samplings, the light component increased by 5.7%, and the minimum miscibility pressure decreased from 32.2 MPa to 28.6 MPa, a drop of 3.6 MPa. Three kinds of displacement states existed in the test area: miscible, semi-miscible and immiscible phases, which account for 2/8, 1/8, and 5/8, respectively. Through research and oilfield practice, the development and adjustment technology of CO2 flooding for different gas injection stages and different types of wells was developed. The oil recovery rate in the test area remained above 1% for four consecutive years. Numerical simulation predicted that the ultimate recovery using CO2 flooding will be 10% higher than that using water flooding.
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