裂缝性页岩油储层三维数字岩心电阻率模拟

Numerical Simulation of Resistivity of 3D Digital Core of Fractured Shale Oil Reservoir

根据吉木萨尔页岩油储层岩样的扫描电镜(FIB-SEM)图像,通过BP神经网络分割方法得到页岩的孔隙、微裂缝结构信息,进而利用改进四参数随机生长法和二维分数布朗运动模型重构了精细的、具有裂缝-基质孔隙双重介质的页岩三维数字岩心,并采用有限元方法对其模拟计算了不同裂缝参数下的有效电阻率,最后分析了不同的润湿性以及裂缝排列方式条件下数字岩心电阻率的变化规律。研究结果表明:微裂缝不同参数的变化能够引起岩石某方向视电阻率的不同程度变化,岩石电阻率与含水饱和度在多种裂缝排列方式下各自存在指数关系,同含水饱和度情况下亲水岩石电阻率更小,且亲水岩石电阻率与含水饱和度函数关系式参数的骤减比亲油状态下更显著。

In order to better characterize the electrical characteristics of developed microfracture reservoir rock,according to the scanning electron microscope(SEM)images of rock samples of Jimusar shale oil reservoir,the pore and microfracture structure information of the shale is obtained by BP neural network segmentation method,and then the fine three-dimensional fracture-matrix pore dual medium digital core of the shale is structured by using improved four parameter growth method and 2D fractional Brownian motion model,and the effective resistivity of digital core under different fracture parameters is calculated by finite element method.Finally,the variation laws of digital core resistivity with water saturation under different wettability and fracture arrangement modes arecalculated and analyzed.The results show that the change of microfracture parameters can cause the change of apparent resistivity of rock in a certain direction.There is an exponential relationship between rock resistivity and water saturation under various fracture arrangement modes.Under the same water saturation,the resistivity of hydrophilic rock is smaller than that of lipophilic rock,and the parameters of the functional relationship between resistivity and water saturation of hydrophilic rock decrease more rapidly than those of lipophilic rock.