微电阻率成像测井三维数值模拟

3D Numerical Simulation of Microelectrical Resistivity Imaging.

采用有限元素法进行三维数值模拟研究微电阻率成像测井响应。模拟过程在全井眼里进行。将井眼、仪器及井周地层划分成适当的三维网络 ,然后用拉普拉斯微分方程在三维网络的每个小单元中离散成一个个线性方程 ,求解这些线性方程形成的方程组得到微分方程的解。网格划分的同时权衡了计算精度、计算时间和计算机容量等因素。对典型地质特征的微电阻率成像测井响应进行了模拟计算 ,结果证明效果良好 ,其方法亦适用于如倾斜裂缝、复合裂缝等较复杂的地质特征的模拟计算。依据计算结果 ,可进行反演研究 ,并给出定量公式 ,从而完成定量评价地质特征的工作。

FEM(Finite Element Method) is used for 3D numerical simulation to study micro resistivity imaging logging responses. The simulation process is made in the full borehole. First, in the simulation logging tool, borehole and formation around the borehole are divided into 3D grids, Laplace differential equation is discreted into a series of linear equations; Then, solutions of differential equation are obtained through solving the linear equations. Calculation accuracy, time and computer capacity, etc., are taken in full consideration while dividing the grides. The micro resistivity imaging responses to typical geological characteristics are simulated, the result of which proves this method is available to estimate complex geological features of deviated and compound fractures. According to the computed results, inversion can be made and the quantitative equation is given so to complete quantitative evaluation of geological features.