表面活性剂对水湿砂岩的渗吸规律及其对采收率的影响

利用国产露头砂岩岩心,研究水湿条件下盐水、非离子表面活性剂、阴离子表面活性剂和阳离子表面活性剂溶液的自发渗吸规律及其对采收率的影响,对比盐水渗吸、表面活性剂溶液渗吸和先盐水渗吸后表面活性剂溶液的渗吸情况.结果表明:在岩心渗透率范围内,各种溶液渗吸的最终采收率为盐水(0.32～0.50)w_(OOIP)(w_(OOIP)为原始含油量),非离子表面活性剂溶液(0.38～0.50)w_(OOIP),阴离子表面活性剂溶液(0.44～0.55)w_(OOIP),阳离子表面活性剂溶液(0.38～0.44)w_(OOIP);同一类型的非离子表面活性剂在具有特定结构时渗吸效果才达到最好,阴离子表面活性剂的渗吸效果一般好于其他类型表面活性剂;盐水渗吸后再进行表面活性剂渗吸,可提高采收率(0.02～0.04)w_(OOIP).

Imbibition behavior of surfactant in water-wet sandstone and its effects on recovery efficiency

Spontaneous imbibition behavior of brine, nonionic surfactant solution, anionic surfactant solution, and cationic surfactant solution and its effects on recovery efficiency were studied in water-wet Chinese outcrop sandstones. The imbibition charateristics were compared in brine, surfactant solution, and sequence of brine and surfactant solution. The results show that the ultimate imbibition recovery efficiency of brine is between 0.32 w_(OOIP) and 0.50 w_(OOIP), where w_(OOIP) refers to the original oil-cut, and that of nonionic surfactants is between 0.38 w_(OOIP) and 0.50 w_(OOIP), and that of anionic surfactants is between 0.44 w_(OOIP) and 0.55 w_(OOIP), and that of cationic surfactants is between 0.38 w_(OOIP) and 0.44 w_(OOIP). The same type of nonionic surfactant with a specific structure could reach the best imbibition results. The imbibition recovery efficiency of anionic surfactant is generally better than that of any other type surfactant. Moreover, if cores are first imbibed in brine and then in surfactant solution, the ultimate recovery efficiency will be improved by (0.02-0.04)w_(OOIP).