考虑润湿反转效应的相对渗透率动态计算方法

润湿反转剂是化学驱提高采收率常用试剂之一，润湿反转剂驱后将改变原始储层岩石性质，对开发中后期油水渗流能力产生较大影响。针对润湿反转过程中相对渗透率曲线难以确定的问题，综合考虑了润湿反转剂导致的界面张力降低及润湿性变化特征，建立了相对渗透率及毛管压力曲线动态计算方法，并分析了润湿反转过程中相对渗透率及毛管压力变化规律。研究表明：油水两相相渗曲线变化同时受到毛管数和润湿性的影响，低毛管数条件下，相渗曲线形态主要受到润湿性的影响，随着毛管数逐渐增大，润湿性的影响减小，最终可以忽略不计。同时，润湿反转剂使得界面张力和毛管力减小，将对渗吸过程产生显著影响，因此，在渗吸驱油过程中，需要对润湿反转剂进行优选，以实现对驱油速度和采收率目标的相对最优。研究结果明确了润湿反转提高采收率过程中相对渗透率及毛管压力的变化规律，为研究润湿反转提高采收率的计算及油藏数值模拟提供了理论基础。

Dynamic Calculation Method of Relative Permeability Considering Wettability Reversal Effect

Wettability reversal reagents are commonly used in chemical flooding to enhance oil recovery. Wettability reversal reagent can change the original properties of reservoir rocks, and then have a great impact on oil-water seepage ability. It is difficult to determine the relative permeability curve in the process of wetting reversal. To solve the problem, a dynamic calculation method of relative permeability and capillary pressure curve was established, which can consider the decrease of interfacial tension and the change of wettability caused by wetting ability reversal reagent. On this basis, the change laws of relative permeability and capillary pressure in the process of wetting reversal were analyzed. The results show that the change of oil-water two-phase permeability curve is affected by both capillary number and wettability. Under the condition of low capillary number, the shape of relative permeability curve is mainly affected by wettability. With the gradual increase of capillary number, the influence of wettability decreases, and finally its influence can be ignored. At the same time, wettability alteration agent reduces the interfacial tension and capillary force, which will have a significant impact on the imbibition process. Therefore, for the process of recovery by imbibition, it is necessary to optimize the wettability alteration agent to achieve the relative optimization of oil displacement speed and recovery target. This study reveals the change law of relative permeability and capillary pressure in the process of EOR by wettability alteration, which provided a theoretical basis for the calculation of EOR by chemical flooding and reservoir numerical simulation.