非均质油藏水驱后化学体系提高采收率效果研究

EFFECT OF CHEMICAL FLOODING ON ENHANCING OIL RECOVERY AFTER WATER FLOODING IN HETEROGENEOUS RESERVOIR

用物理模拟的方法对比了非均质油藏水驱后期分别采用聚合物驱、高分子表面活性剂驱、化学堵水等方法提高采收率的效果差异。通过多孔介质中表现出的阻力效应及运移特征,探讨了不同驱替介质在非均质油藏中的调驱机理和液流转向效果。进一步通过并联填砂管模型中的驱油实验,考察了水驱后使用不同化学驱替方式对剩余油的动用特征及提高采收率的潜力。结果显示,相同驱替速度下,聚合物的阻力系数上升快但平衡值低;高分子表面活性剂及与原油产生的乳状液阻力系数上升慢,但平衡值高。三种驱替方式都在一定程度上改善了开发效果,但相比之下高分子表面活性剂驱效果更为明显。主要由于高分子表面活性剂与原油的乳化作用使高渗透层的残余油得到启动,而生成的乳状液的阻力效应又使得液流转向波及到低渗透层。这种综合作用使该驱替方式提高采收率效果好,含水率降幅大且维持时间较长,对于非油藏水驱后改善开发效果,进一步提高采收率具有明显优势。

The recovery enhancing effects of different flooding methods,such as polymer flooding,high molecule weight surfactant flooding,chemical water plugging were studied by physical simulation.The flow characteristics of different flooding systems and their function to enlarge the swept volume of oil reservoir were compared each other in the paper,by detecting the resisting force formed in porous media.Further more,flooding experiments of different chemical flooding systems in parallel sand-packed module were down to examine their efficiencies and abilities for enhancing oil recovery.Experiment results showed that,under same flooding rate,the resistance factor of polymer increase fast but can only reach a low level at last,while the resistance of high molecule weight surfactant and emulsion produced increase slowly but can reach a high level.Three flooding methods can all improve the development effect in a degree,but surfactant flooding is the best one.The reasons are that,the surfactant selected in the paper can result to emulsification with oil,and then induce high resisting force in porous media.The integrated effect can start-up the residual oil in high permeability layer,and at same time,turn the route of flooding fluid to low permeability layer.In this way,the recovery factor and swept efficiency can be enlarged greatly,and the development effect of heterogeneous reservoir can be improved correspondingly.Thus,using surfactant flooding after water flooding in heterogeneous reservoir has a distinct advantage for enhancing oil recovery.