低碱ASP三元复合驱技术的适用界限分析

针对大庆油田三元复合驱的油层条件 ,利用渗透率变异系数为 0 .72的三层非均质模型进行了驱油物理模拟实验 ,系统地研究了碱及聚合物浓度对ASP驱采收率的影响 ,并利用加隔层模型和合注分采方式 ,研究了碱浓度对启动中、低渗透层的影响。结果表明 ,低碱ASP驱在提高体系粘度的同时也造成界面张力升高 ,因而有其适用界限。在给定的非均质油层条件下 ,ASP驱存在一个临界粘度 ,只有达到临界粘度后 ,采收率才随界面张力的降低而升高 ,即界面张力发挥作用的前提是充分扩大波及体积。若为追求高粘度而过于降低碱量或取消碱 ,也会因洗油效率下降而影响采收率。低碱ASP驱可以保证体系足够的粘度 ,更有效地启动中、低渗透层 ,即使界面张力仅达到1 0 - 2 mN/m ,也可获得满意的驱油效果

Analysis of application boundary of low base number asp flooding technology

As for the formation conditions of ASP flooding pilot in Daqing Oilfield, the effects of polymer and alkali concentrations in ASP solution on oil recovery efficiency were studied by means of oil displacement experiments and three layers of heterogeneous models with a permeability variation factor of 0.72. Meanwhile, the effects of alkali concentration on the oil recovery efficiency of middle permeability and low permeability formation were investigated using the models with intermediate layers and the ways of multi layer injection and separate layer production. The results showed that there is a boundary for applying low base number ASP flooding, since low alkali concentration could make ASP solution have high viscosity and high interfacial tension (IFT). ASP solution has a boundary viscosity to a certain heterogeneous formation. Only when viscosity of ASP solution is over this boundary, the oil recovery efficiency will increase with reduction of IFT. But it is not beneficial to greatly decrease the alkali concentration or cancel alkali for increasing the apparent viscosity of ASP solution. The low base number ASP flooding technology can guarantee ASP solution with enough apparent viscosity for developing the middle permeability and low permeability layers. Though the IFT of ASP solution with low alkali is only 10\+\{-2\} mNm, the satisfactory displacement effects can be achieved.