基于孔隙网络模拟及储层物性时变的数值模拟方法研究

Numerical simulation method based on pore network simulation and time-varying reservoir physical properties

水驱油藏开发中后期由于长期受水冲刷作用,采用油藏最初的储层参数及相对渗透率曲线进行模拟难以真正反映油藏开发后期油水运移及分布状况。基于孔隙网络模拟方法建立了某碳酸盐岩样品(样品C)的孔隙网络模型。通过对比均质Berea砂岩,分析了样品C的孔喉结构特征,进行了孔隙级渗流模拟,分析了不同过水倍数下储层润湿性及渗透率的变化关系;而后把该计算结果应用到储层渗流模拟中,实现了储层物性的时变;在此基础上,对基于空隙网络模拟和储层物性时变方法建立的M区块碳酸盐岩油藏实例模型进行计算。结果表明:在油藏开发中后期,天然水驱强度达到一定程度时出现了含水率增加较快的情况,这表明模型反映了矿场实际,提高了模拟精度。

In the middle and late stage of water flooding oil reservoir development,due to long-term water erosion,it is difficult to reflect the oil-water migration and distribution in the later stage of reservoir development by using the initial reservoir parameters and relative permeability curves.The pore network model of a carbonate rock sample(sample C)was established based on the pore network simulation method.By comparing with the homogeneous Berea sandstone,the pore throat structure characteristics of the carbonate rock sample C were analyzed,and the pore-level seepage simulation was carried out to analyze the variation relationship between the reservoir wettability and permeability under different displacing water multiples.Then,the calculation results were applied in the reservoir seepage simulation and the time-varying reservoir physical properties were realized.On this basis,the calculation of the M Block carbonate rock oil reservoir model which was build based on the pore network simulation and the time-varying reservoir physical properties method was carried out.The result shows that in the middle and late stage of reservoir development,when the natural water flooding intensity reaches a certain degree,the water cut increases more rapidly,which indicates that the model reflects real condition of the block,and improves the simulation accuracy.