井间电磁场的一维、二维联合反演方法

提出了针对轴对称二维井间模型的一维、二维联合反演方法.该方法基于纵向成层背景地层的Green函数，以一维反演结果作为联合反演的迭代初始值，同时反演一维背景地层和二维异常剖面的电导率.采用递推技术计算Green函数的系数，可以很方便地同时得到Green函数对空间坐标的积分和对背景层电导率的微分，大大加快了计算雅可比矩阵〖WTHX〗M〖WTBZ〗的速度并使计算方便、准确.反演实例说明了该方法的有效性.反演实例还显示，背景层电导率较二维成像剖面的电导率收敛速度要快，测量数据的精度对二维剖面电导率成像质量的影响大于对背景层电导率分布的影响.

A combined 1-D/2-D inversion algorithm of cross-hole electromagnetic fields

A combined 1-D/2-D inversion algorithm is proposed for a 2-D cross-hole model with cylindrical symmetry. Based on the Green's function of longitudinal layered background medium, the algorithm can simultaneously invert the conductivities of the 1-D background and the 2-D anomalous sections by taking the result of the 1-D inversion as the initial model for the combined inversion. Since the coefficients of the Green's function are calculated through a recursion technique, the integral of the Green's function with respect to the space coordinates and the differential of the Green's function with respect to the background conductivities can be simultaneously obtained very conveniently, and thus the calculation of the Jacobian Matrix M becomes more quickly, conveniently and accurately. Inversion examples show the effectiveness of the algorithm. The examples also indicate that the reconstruction of the 1-D background conductivities converges more quickly than the reconstruction of the conductivities on the 2-D imaging section, and that the effect of precision of the measured data on the imaging of the 2-D section is greater than that on the distribution of the background conductivities.