用迭代反演算法进行井间电磁二次成像

Iterative Inversion Algorithm for Crosshole Electromagnetic Reimaging

魏宝君，张庚骥．用迭代反演算法进行井间电磁二次成像．测井技术，１９９９，２３（３）：１６３～１６７利用基于逐次逼近解法的迭代反演算法对井间地层电导率构造进行成像。第一次成像在整个井间范围进行，可以确定出电导率异常体所在的区域及该区域内电导率的分布，但反演的电导率值与实际电导率数值差别较大。在第一次成像的基础上利用相同的算法可以进行第二次成像。由于第二次成像目标范围小，在成像中可以减小像素的尺寸，并且将第一次成像结果作为参考模型，从而提高了计算精度和成像分辨率。

The iterative inversion method based on SAM is applied in imaging the formation conductivity structure between two holes.After the first imaging of the whole crosshole area, the anomalous conductivity region and the conductivity distribution in this region are determined, but the determined conductivities are much different from the given conductivities. Then the structure is reimaged using the same method. The imaging region is relatively small and the area of each pixel is then decreased during the second imaging process, and the reference model is selected on the basis of the first imaging result, so the reimaging process improves the computation precision and the imaging resolution. The examples indicate that the second imaging is necessary and effective.