稠油油藏化学驱实验研究

An Experiments Study on Chenmical Flood for Heavy Oil Reservoirs

在65℃测定0.01%RS-2(一种季铵盐表面活性剂)溶液、0.05%RS-2+0.5%Na2CO3溶液、0.05%RS-2+0.5%NaOH溶液与孤岛稠油之间的界面张力,形成的乳状液稳定性、乳化液滴直径分及3个表面活性剂体系(段塞尺寸1.0PV)填砂模型驱油效率。这3个体系的油水界面张力分别为100、10-1、10-2mN/m数量级;油水体积比1∶1的O/W稠油乳状液60min析水率分别为67%、12.5%、8%;乳化液滴平均直径分别为18、15、3μm。在均质模型中,1PV0.05%RS-2+0.5%NaOH溶液的驱油效果最好,在水驱基础上(采收率25.4%)提高采收率22.3%。在非均质模型中,0.05%RS-2+0.5%Na2CO3溶液驱油效果最好,驱替压力增幅高、持续时间长,在水驱基础上(采收率16.0%)提高采收率18.0%。认为在非均质稠油油藏中乳状液稳定、粒径稍大于高渗带孔径的化学驱油体系驱油效率更高;用非均质模型优选的稠油化学驱油体系更符合油藏实际。

In this experimental study conducted at 65℃,three aqueous surfactant solutions（ASSs） were used：0.01%RS-2,a quarternary ammonium salt surfactant; 0.05%RS-2＋0.5%Na2CO3; and 0.05%RS-2＋0.5%NaOH. The interfacial tension between these ASSs and Gudao heavy crude oil（HCO） was of magnititude 10^0,10^-1,and 10^-2 mN/m,respectively. The water separation in 60 min from the emulsions formed by mixing the ASSs and the HCO in equal volume ratio,demonstrating the emulsion stability,was of 67.0%,12.5%,and 8.0% and the droplet size in the emulsions was of 18,15,and 3 μm in average,respectively. In ASS flooding experiments on sand packs the highest enhancement in oil recovery from homogeneous sand packs was observed with 0.05%RS-2＋0.5%NaOH solution（1 PV） injected,reaching 22.3% after 25.4% oil recovered by water flood,and from heterogeneous sand packs——with 0.05%RS-2＋0.5%Na2CO3 solution（1 PV） injected,being of 18.0% after 16.0% oil recovered by water flood,and in the later case the injecting pressure was higher and kept at a higher level in longer time duration. It was considered that a chemicalflooding solution was more effective in heterogeneous heavy oil reservoirs when it could create more stable emulsions with droplets slightly larger in size than the pore size in highly permeable zones and the chemical flooding system screened through heterogeneous physical model flooding tests might be more suitable for the real reservoir.