ASP三元复合驱油体系在长岩心中的运移规律

Study on the migration of ASP flooding system in long core

为研究大庆油田ASP(碱、表面活性剂、聚合物)三元复合驱油体系在地层中的运移规律,制备了渗透率为479 mD,长度为6 m的填砂管模型,根据现场提供的复合体系配方在45℃环境下进行恒温驱替,分析采出液的化学剂浓度、黏度、界面张力的变化。结果表明,在三元驱阶段,复合体系的注入程度越高,含水率越低,采收率越高,ASP注入开始1.5 PV后复合体系驱油效果彻底失效。复合体系的化学剂浓度和黏度的损失程度为黏度(6倍)>表面活性剂(4倍)>聚合物(3倍)>碱(2倍),由于黏度的损失过大,复合体系在后1/12井距失去了控制流度比的作用。碱的存在使得超低界面张力(0.001 mN/m)可以维持前1/2井距,低界面张力(0.01 mN/m)可以维持后1/2井距。

To study the migration of ASP(alkali/surfactant/polymer)flooding system in the formation in Daqing Oilfield,a sand filling tube model with a permeability of 479 mD and a length of 6 m was prepared,according to the practical formula applied in oilfield,isothermal displacement was carried out at 45℃.The concentration,viscosity and interfacial tension of the produced fluid were analyzed.The results showed that in the ternary flooding stage,the higher the injection degree was,the lower the water content and the higher the recovery factor would be;the flooding effect of the system completely failed after ASP started 1.5 PV.The loss degrees of chemical agent concentration and viscosity in the system were as follows:viscosity(6 times)>surfactant(4 times)>polymer(3 times)>alkali(2 times).Because of the excessive loss of viscosity,the system lost the function of controlling the fluidity ratio in the latter 1/12 well spacing.Because of the presence of alkali,ultralow interfacial tension(0.001 mN/m)could be maintained for the first 1/2 well spacing,while low interfacial tension(0.01 mN/m)could be maintained for the rear 1/2 well spacing.