“CO_(2)+表面活性剂”复合体系优化及驱油效率

Optimization of “CO_(2)+surfactant” composite system and evaluation of the oil displacement efficiency

国内矿场应用CO_(2)驱提高原油采收率普遍存在CO_(2)与原油混相程度低导致驱油效率低的问题,为提高CO_(2)—原油混相程度,进行"CO_(2)+表面活性剂"复合驱油研究,在超临界CO_(2)中测试和对比油气两亲性表面活性剂Superweet320、SPO5和LAE4的溶解度、降黏、增膨和降低油气界面张力性能,确定SPO5作为细管驱替实验用表面活性剂。细管实验表明,在0.8 PV段塞尺寸条件下,"CO_(2)+表面活性剂(质量分数为0.8%SPO5)"复合驱提高驱油效率8.44百分点。通过理论分析及实验评价系统方法,优选出适合目标区块的表面活性剂,采用复合驱方式能够有效提高驱油效率。

The application of CO_(2) flooding in domestic fields to enhance oil recovery generally suffers from the low miscibility between CO_(2) and crude oil, resulting in rather low oil displacement efficiency. In order to improve the miscibility, the study on “CO_(2)+surfactant” combined flooding is conducted. In supercritical CO_(2), the solubility, viscosity reduction, expansion and interfacial tension reduction performances of oil-gas amphiphilic surfactants Superweet320, SPO5 and LAE4 are tested and compared, and SPO5 is determined as the surfactant for the thin-tube displacement experiment. The thin-tube experiment shows that under the condition of 0.8 PV slug size, the “CO_(2)+surfactant”(the mass fraction is 0.8 wt% SPO5) combination flooding can increase oil displacement efficiency by 8.44 percent points. Through theoretical analysis and experimental evaluation system method, the surfactant suitable for the target block is selected, and the combined flooding method can effectively enhance the oil displacement recovery.