孔洞型储层电阻率理论模拟及影响因素

Theoretical Simulation and Analysis Factors of Resistivity in Vuggy Reservoir

碳酸盐岩储层导电机理复杂,电阻率影响因素众多,储层划分及流体性质识别难度较大。通过构建合理的孔隙结构物理模型,理论模拟储层电阻率,并对各种影响因素(喉道粗细、地层水电阻率、岩石基质电阻率、孔洞延展方向及大小等)逐一进行分析,进一步探讨了各因素对电阻率的影响程度,较好地解释了电阻率异常层的成因。孔洞型储层电阻率随喉道直径增加快速下降,而随基质、地层水电阻率增加而增大;平行电流方向的孔洞延展对电阻率的影响高于垂直电流方向的孔洞延展,孔洞尺寸沿着电流方向增大,电阻率呈降低趋势。喉道直径对电阻率的影响高于孔洞尺寸;喉道直径对全含水岩石电阻率的影响大于全含油,而岩石基质电阻率、地层水电阻率、孔洞延展方向及大小则相反。

Because of the many factors influencing the resistivity of carbonate reservoir and the complex conductive mecha-nism,it is difficult to identify the reservoir and interpret the property of fluids. On the basis of pore-structure physical model, we simulated the resistivity of reservoir,and analyzed the factors which affect the resistivity of reservoir. The factors include the throat size,the resistivity of formation water,and the resistivity of matrix,and the vuggy size,and so on. At last,the influencing degree to resistivity of reservoir is discussed and the reason of abnormal resistivity in carbonate is interpreted in this paper. The resistivity of reservoir gradually reduces with the throat diameter increasing,and increases as the resistivity of matrix and formation water increases. Vuggy extension influence on resistivity along the direction of the current is higher than that along the vertical current direction. With the vuggy size along current direction increasing,the resistivity reduces. The effect of throat diameter on the resistivity of reservoir is bigger than vuggy size. The effect of throat diameter on the resistivity of completely water-saturated rocks is bigger than on completely oil-saturated rocks,but for the resistivity of the matrix and the formation water,the extended direction and size of the vuggy,the condition is opposite.