耦合势有限体积法模拟海洋移动导线源三维频率域电磁响应  

Marine moving-wire-source CSEM 3D response simulation with the coupled potential finite volume method

作　　者：周建美[1] 李貅[1] 戚志鹏[1] 

机构地区：[1]长安大学地质工程与测绘学院,陕西西安710054

出　　处：《石油地球物理勘探》2018年第3期587-596,共10页Oil Geophysical Prospecting

基　　金：国家自然科学基金重点项目(51139004);国家自然科学基金项目(41704108);中国博士后基金项目(332100150023)联合资助

摘　　要：本文采用耦合势有限体积法建立了一套快速计算海洋移动导线源电磁响应的三维数值模拟技术。基于电场矢势标势分解将Maxwell方程转换为关于矢势和标势的亥姆霍兹方程;采用洛伦兹规范整理得到对称形式的离散系数矩阵。对导线源采用直接离散方法,基于ILUT(Incomplete LU Preconditioner with Threshold)预处理的BICGSTAB(Biconjugate Gradient Stabilized)迭代算法实现离散线性方程的求解。为了减少移动源总的计算时间,提出采用解的初值重置技术加快正演模拟的速度,即利用发射源移动前的电磁场响应作为发射源移动后的离散方程的初始解。数值计算结果表明:对导线源采用直接离散方法,当导线源的长度大于源周围网格长度的4倍以上时,源附近离散误差显著减小;相比常规的直接迭代算法,采用解的初值重置技术能够减少迭代次数、提高正演计算速度。We propose a marine controlled-source(moving-wire-source)electromagnetic(CSEM)3 Dresponse simulation with a coupled potential finite volume method.First Maxwell's equations are transformed into coupled scalar-vector potential Helmholtz equations with the electric field scalarvector potential decomposition.A discrete linear equation with symmetry coefficient matrix is obtained with Lorentz gauge.Then the direct discrete method is used for the source.The linear equation of marine CSEM is solved with BICGSTAB iteration after ILUT pre-conditioning.In order to speed up the moving-source iteration calculation and forward modeling,we develop a solution initial value reset technique,namely the response before source moving is used as a solution initial value for the discrete equation after source moving.Based on numerical model tests,the discrete error around the source is significantly reduced when the length of source is four times of the source-mesh length;and the forward modeling with initial value reset is faster than conventional forward modeling.All this proves the effectivity of the proposed approach.

关 键 词：海洋可控源电磁法 移动导线源 有限体积法 洛伦兹规范 

分 类 号：P631[天文地球—地质矿产勘探]