THREE-DIMENSIONAL FAST INVERSION OF BOREHOLE-SURFACE DATA
LV Yu-zeng1,2, RUAN Bai-yao2, PENG Su-ping1
1. State Key Laboratory of Coal Resources and Safe Mining, China University of Mining & Technology, Beijing 100083, China;
2. College of Earth Sciences, Guilin University of Technology, Guilin 541004, China
Abstract:Based on an analysis of coefficient matrix formed from three-dimensional FEM (finite element method) forward with tetrahedral cells division, the authors used MSR (Modified Sparse Row) memory method and SSOR-PCG for solving equations to realize the fast forward of borehole-surface IP surveying. The inversion technique is based on the least-squares and CG (conjugate gradient), and it makes use of the simple relationship between Jacobian matrix A and the forward equation, which needs only to solve and multiplying a vector and avoids direct calculation and access of matrix. The 3-D fast inversion with minutes of PC time is achieved. The inversion results of three-dimensional borehole-surface forward synthetic data reproduce the known models approximately.
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