孔隙结构与含油岩石电阻率性质理论模拟研究

Theoretical simulation of the resistivity and pore structure of hydrocarbon bearing rocks.

应用建立在有效介质和逾渗理论基础之上的网络模型 ,模拟岩石孔喉大小及分布、水膜厚度、孔隙连通性等微观孔隙结构特征参数的变化对含两相流体岩石电阻率的影响。理论模拟结果表明 ,岩石孔隙结构的改变对油气层的电阻率变化有明显的控制作用 ,其中孔隙连通性、岩石固体颗粒表面束缚水水膜厚度等因素的影响尤其突出。对复杂孔隙结构的储集层 ,一定要充分重视孔隙结构对岩石电阻率性质的控制作用。对该储集层岩石的含油饱和度定量评价 ,不能照搬传统的阿尔奇模型 ,而应区别不同的孔隙结构类型 ,建立和采用不同的饱和度评价模型。

A network model, which is established upon the effective medium and the percolation theories, is used to simulate the pore structure and its effects on the resistivity of hydrocarbon bearing rocks with complex pore structure. The simulation demonstrates that the pore connection, brine film thickness, pore-throat size, and pore/throat ratio play important roles in resistivity properties of hydrocarbon bearing rocks. The comparison and discussion of various I_r-S_w relations of the simulated rocks with different pore structures are made. The simulated results strongly demonstrate that the Archie's formula will not properly function in those complex formations that are common in the sedimentary basins of China. It is necessary to establish a specific model to evaluate the hydrocarbon saturation of the formation rocks according to their pore structure.