双侧向电阻率测井反演算法研究

双侧向测井仪因其激励源的复杂性给其测量数据的反演带来了极大的困难．本文利用变形玻恩（Born）迭代法对轴对称二维非均匀介质中双侧向测井仪的位场数据进行了严格反演．在每一次迭代过程中采用了高效数值模式匹配的正演计算方法，它可半解析地求出反演中所需计算的格林（Green）函数及其偏导数，同时利用所推导出的位场非线性积分方程中积分运算的半解析形式，大大提高了计算效率和反演质量．通过反演实例表明，反演结果与电导率原状剖面吻合较好，并且受噪声影响较小．

AN ALGORITHM FOR THE INVERSION OF RESISTIVITY MEASUREMENTS FROM DUAL LATEROLOG TOOL

The complex excitation of the dual laterolog tool results in the difficulty of the potential field inversion. In this paper, the Distorted Born Iterative Method （DBIM） is applied to deal with the nonlinear inversion problem of the potential measurements from Dual laterolog tool in a two-dimensional axisymmetric medium. In each iteration of the DBIM an efficient numerical mode──marching method is used to solve the forward problem. This method provides a semianalytic expression for the Green's Function and its derivatives required in the inversion, and then deduces a semianalytic expression of the integration in the nonlinear integral equation. Therefore, the efficiency and accuracy are improved further more. The several numerical resultS show that inversion results agree well with the original conduchvity profile, and this inversion scheme is qinte robust under random noise condition.