基于局部加密的非结构化网格SNMR方法二维Occam反演研究  

2-D Occam inversion study of snmr method on unstructured grids based on local encryption

作　　者：詹林 潘剑伟 高健 张成丽 杨晨 钱伦 槐玉鹿 ZHAN Lin;PAN JianWei;GAO Jian;ZHANG ChengLi;YANG Chen;QIAN Lun;HUAI YuLu(School of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China;Key Laboratory of Karst Geological Resources and Environment of Ministry of Education,Guizhou University,Guiyang 550025,China)

机构地区：[1]贵州大学资源与环境工程学院,贵阳550025 [2]贵州大学喀斯特地质资源与环境教育部重点实验室,贵阳550025

出　　处：《地球物理学进展》2024年第3期1089-1101,共13页Progress in Geophysics

基　　金：国家自然科学基金青年基金资助项目(42004122);贵州省科技计划资助项目([2020]1Y173)联合资助。

摘　　要：地面核磁共振(SNMR)方法作为一种能直接探测地下水的方法,对地下含水层有着较高的探测灵敏度.传统的SNMR反演能在一定的深度范围内获取含水量的层位分布信息,但在有限脉冲激发下,对含水边界的分辨能力具有局限性.为了克服上述问题,实现对含水构造边界分布特征探测能力的提升,本文首先采用数值模拟方法,建立古河道、含水断层和富水岩溶三种地球物理模型,并对模型进行非结构化网格剖分及局部加密的非结构化网格剖分,对比分析其各自在最小模型约束及方向约束下的Occam反演成像效果.然后,通过青藏高原的一处场地试验,对数值模拟进行了验证;结果表明,对高含水量区域进行非结构化网格的局部加密,能够有效提升含水构造边界特征的分辨能力,同时结合先验信息进行方向约束,可以得到更为准确的反演结果.The Surface Nuclear Magnetic Resonance(SNMR) method,as a direct means of detecting subsurface water,exhibits high sensitivity in exploring aquifer properties.Traditional SNMR inversion techniques can provide information on the distribution of water content within a certain depth range,but they are limited in their resolution of water boundaries under finite pulse excitations.In order to overcome these challenges and enhance the capability to detect the distribution characteristics of water-bearing structures,this study employs numerical simulation methods.Initially,three geological models—ancient river channels,aquifer faults,and water-rich Karst formations are established.Unstructured mesh partitioning and localized mesh refinement are applied to these models.Comparative analyses of the Occam inversion imaging effects under minimum model constraints and directional constraints are conducted.Subsequently,the study validates the numerical simulations through field experiments in the Qinghai-Xizang Plateau.The results demonstrate that local mesh refinement on high-water-content areas using unstructured grids effectively enhances the resolution of water structure boundaries.Additionally,incorporating directional constraints along with prior information leads to more accurate inversion results.

关 键 词：地面核磁共振 局部加密 非结构化网格 OCCAM反演 方向约束 

分 类 号：P631[天文地球—地质矿产勘探]