基于非结构化网格的井地电阻率法三维正演模拟及异常特征研究  

Research on 3D hole-to-surface resistivity forward modeling and anomaly based on unstructured meshes

作　　者：王智[1] 方思南 姜匡义 马伟 卢新勋 WANG Zhi;FANG SiNan;JIANG KuangYi;MA Wei;LU XinXun(School of Electronics and Information Engineering,Yangtze University,Jingzhou 434023,China;College of Geophysics and Petroleum Resources,Yangtze University,Wuhan 430100,China)

机构地区：[1]长江大学电子信息学院,荆州434023 [2]长江大学地球物理与石油资源学院,武汉430100

出　　处：《地球物理学进展》2022年第4期1620-1630,共11页Progress in Geophysics

基　　金：国家自然科学基金(41604093);中国博士后科学基金(2017M622382);大学生创新创业训练计划项目(2019090)联合资助。

摘　　要：起伏地形对类电阻率法的影响不可避免,纯地形会对观测的视电阻率造成异常假象,即使同一种地形对于不同的观测装置其地形引起的异常也完全不同,因此复杂地形条件下的视电阻率异常解释起来十分困难,近年来,在水平及起伏地表情况下的地面电阻率法三维正演取得诸多进展,已逐渐成熟化和实用化,但是起伏地形下井中类电阻率法的正演模拟研究不多,勘探前期对电性体的异常形态特征认识不足.本文采用Gmsh进行几何建模和网格剖分,基于非结构化四面体网格模拟复杂地形,实现了三维井地电阻率法的正演模拟,通过两个理论模型检验了代码正确性与算法的有效性之后,选择了山峰地形下低阻球体、山谷地形下低阻球体和一个山脉峡谷复杂地形模型作为研究对象,给出了井地二极、井地三极观测装置下的正演计算结果,对起伏地形下的典型地质体的异常形态特征进行了分析总结,可用于指导野外生产,提高勘察工作的效率和勘探效果,并为进一步研究起伏地表下三维井地电阻率反演奠定基础.The influence of undulating terrain on the resistivity method is inevitable.Pure terrain will cause the illusion of anomalous in the observed apparent resistivity.Even the same terrain will cause completely different anomalies caused by different surveying system.Therefore,under complex terrain conditions,It is very difficult to interpretation for the apparent resistivity anomaly.Three-dimensional forward modeling of the ground resistivity method that under horizontal and undulating surface conditions which has a lot of progress in recent years.It is more matured and more become practical.There are not much studies and there is insufficient understanding of the abnormal morphological characteristics of electrical bodies in the early stage of exploration.In this paper,Gmsh is used for geometric modeling and meshing.Complex terrain is generated by unstructured tetrahedral grids,and the forward simulation of three-dimensional well-ground resistivity method is realized.The correctness of the code and the algorithm are verified used two theoretical models.Low-resistance sphere were selected respectively under the mountain topography and the valley topography,and a mountain and complicated terrain model as the research objects with the different surveying system under the hole-to-surface pole-pole and pole-dipole.The calculation results are analyzed and summarized on the anomalous morphological characteristics of typical geological bodies under undulating terrain,which can be used to guide field production,improve the efficiency and exploration effect of survey work,and it has setup a basis for the inversion of three-dimensional hole-to-surface resistivity under undulating ground.

关 键 词：起伏地形 电阻率法 非结构化 Gmsh 正演模拟 

分 类 号：P631[天文地球—地质矿产勘探]