各向异性地层电磁脉冲测井响应的FDTD模拟

利用三维柱坐标系时域有限差分（FDTD）方法计算了各向异性地层中电磁脉冲测井响应。首先验证了算法的正确性及可行性，然后分析了均匀无限厚各向异性地层中及考虑泥浆、围岩、侵入等因素存在的复杂各向异性地层中的电磁脉冲测井响应特征。结果表明：视电阻率随着倾斜角度的变化而变化；高阻地层比低阻地层受泥浆的影响更严重；高阻围岩比低阻围岩对目的层的影响更大；侵入带对视电阻率的影响非常明显，必须对测井资料进行侵入影响校正。

Calculation of electromagnetic pulse logging response in anisotropic formation using FDTD method

The response of electromagnetic pulse logging in anisotropic formation was simulated with three-dimensional finite-difference time-domain(FDTD)method in cylindrical coordinate system.The correctness and feasibility of the algorithm was validated.The response characters of electromagnetic pulse logging were analyzed in uniform anisotropic formation and complex anisotropic formation by taking mud,shoulder bed,invasion and other factors into consideration.Results show that apparent resistivity changes with the dip angle,the influence of mud on high-resistivty formation is more than that on low-resistivity formation,and the influence of high-resistivty shoulder beds on target is more than that of low-resistivity ones.Moreover,the influence of invasion zone on apparent resistivity is noticeable,and therefore correction for it is needed.