榆树林油田特低渗透扶杨油层CO_2驱油效果评价

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。

Evaluation of oil displacement by CO2 at Fuyang extra-low permeability layer in Yushulin oilfield

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.