基于两层含水采空区瞬变电磁场数值模拟的拟地震偏移成像

摘要

The transient electromagnetic method is an effective exploration method for the coalfield mined-out area. The pseudo⁃seismic processing and interpreting of TEM have gradually become a hot research spot of EM exploration and made some breakthroughs. In this study. The authors employed the pseudo⁃seismic processing and interpreting method in coal mine goaf detection for higher detecting ac⁃curacy. With 3D finite difference time domain method of TEM, a model with two water bearing gobs was simulated. Pre⁃condition regu⁃larized conjugate gradient algorithm was used to realize stable transform from the diffusion field to the virtual wave field. And pulse com⁃pression was applied to virtual wave field. Finally, three⁃dimensional interpretation of the model was realized through the Kirchhoff inte⁃gral equation downward migration imaging of the fictitious wave field data.%瞬变电磁法是探测煤田采空区的一种有效方法。瞬变电磁拟地震处理解释方法研究日渐成为电磁勘探领域的热点并且取得了突破性进展，所以可以把瞬变电磁拟地震处理解释运用到煤田采空区的探测中来提高勘探精度。文中在瞬变电磁三维时域有限差分数值模拟两层含水采空区模型的基础上，运用预条件正则化共轭梯度算法实现了瞬变电磁扩散场到虚拟波场的稳定转化，并对虚拟波场进行了脉冲压缩处理；最后通过克希霍夫积分解，对虚拟波场进行延拓成像，实现了两层含水采空区模型的三维解释。