煤田地质与勘探2025，Vol.53Issue(11)：53-65,13.DOI:10.12363/issn.1001-1986.25.05.0407
巷-孔瞬变电磁自适应波场反变换及虚拟波场特征
Self-adaptive inverse wavefield transform and derived pseudo-wavefield characteristics under roadway-borehole observation of transient electromagnetic data
摘要
Abstract
[Objective]To address the challenge of detecting aquifers outside the roadway excavation contour,this study combined the close-range detection via roadway-borehole transient electromagnetic(TEM)method with the wavefield transform.This will help simultaneously receive detection signals in front of the mining face and outside the roadway excavation contour while also highlighting the boundary information of aquifers.Moreover,to obtain a pseudo-wave-field featuring both reasonable kinematic characteristics and high sensitivity to changes in the electrical structures of strata,this study proposed a self-adaptive algorithm of inverse wavefield transform,thereby improving the accuracy and efficiency of the inverse wavefield transform of roadway-borehole TEM data.[Methods]The TEM wavefield transform faces some inherent limitations,such as a large dynamic range of the kernel function and high ill-posedness of the in-verse transform equation.To address these challenges,this study,using the analytical solutions of the kernel function of wavefield transform over an infinite interval,proposed a method to automatically determine the interval of integration for inverse wavefield transform based on parameters such as the acquisition time of TEM data.The proposed method can minimize the dynamic range of the kernel function.Furthermore,using the precise integral method,this study developed an algorithm for solving inverse wavefield transform equations based on a self-adaptive step size of integration and itera-tion process,thus converting the solving of the ill-conditioned system of equations into solving an integral stably.For aquifers outside the roadway excavation contour,their TEM response signals were determined through forward model-ing using the finite volume method.Accordingly,the pseudo-wavefield records of their vertical magnetic field compon-ents of TEM data were obtained.Moreover,the inverse wavefield transform of measured TEM data from boreholes was also conducted using the same algorithm.[Results]The results indicate that the obtained pseudo-wavefield records ex-hibited reasonable kinematic characteristics.The reflected wave trajectories in the pseudo-wavefield records were reas-onably similar to the time-distance curves in the single-shot seismograms.Regarding numerical accuracy,the back sub-stitution results of the pseudo-wavefield data were highly consistent with the forward modeling-derived or measured data,with the maximum relative errors all below 10%.[Conclusions]Under the roadway-borehole observation mode of TEM data,the proposed self-adaptive algorithm of inverse wavefield transform enables the acquisition of pseudo-wave-field records with clear physical significance and reliable numerical accuracy.Furthermore,the obtained pseudo-wave-field is highly sensitive to the aquifer boundaries with significant electrical contrasts,providing robust data support for further pseudo-wavefield imaging.关键词
瞬变电磁法/巷-孔观测模式/波场变换/自适应/虚拟波场特征Key words
transient electromagnetic(TEM)method/roadway-borehole observation mode of TEM data/wavefield transform/self-adaptive/pseudo-wavefield characteristic分类
天文与地球科学引用本文复制引用
范克睿,郭建磊,王若宇,庄明,樊芳泽,徐胜,赵文涛..巷-孔瞬变电磁自适应波场反变换及虚拟波场特征[J].煤田地质与勘探,2025,53(11):53-65,13.基金项目
国家自然科学基金项目(42407260,42304163) （42407260,42304163）
山东省自然科学基金项目(ZR2022QE242) （ZR2022QE242）
中国地球物理学会工程物探检测重点实验室开放研究基金项目(CJ2022GA01) （CJ2022GA01）
泰山学者青年专家项目(tsqn202312192) （tsqn202312192）
