方位梯度电极系的正反演

FORWARD AND INVERSION OF AZIMUTHAL LATERAL SONDE

针对环井周的非均质地层模型，利用三维有限元方法模拟了方位梯度电极系的测井响应．结果表明，在非均质程度比较小的情况下，各个方位上的响应之间差别不大，与真实的电阻率分布差别也不大；反之，则差别很大．其特点是所测得的响应远远低于较高的真电阻率值，而接近较低的真电阻率值．因此，有必要对测井响应进行校正．考虑到传统的校正方法的弊端，本文利用非线性反演方法求取真实的电阻率分布，数值模拟的结果表明了此方法的可行性．

Appling 3D finite element method, responses of an azimuthal lateral sonde in an inhomogeneous formation model around a borehole are simulated. Results show, in the less inhomogeneous situation, the response on each azimuthal has less difference with the true resistivity distribution and others also. Otherwise, the difference is great. The response is much lower than the high resistivity and much closer to the low resistivity. So a correction is necessary. The true resistivity distribution is solved by a nonlinear inversion method due tO the drawbacks of old correction methods. Numerical simulations show the method is feasible.