平行巷道条带异常体在透射槽波层析成像中造成的假象  

Artifact resulted from the banded anomalous body parallel to the roadway in the transmission channel wave tomography

作　　者：杜艳艳[1] 冯磊[1,2] 李松营 姚小帅 廉洁 余为维 

机构地区：[1]河南理工大学资源环境学院,河南焦作454000 [2]中原经济区煤层(页岩)气河南省协同创新中心,河南焦作454000 [3]义马煤业集团股份有限公司地质研究所,河南义马472300 [4]中国地质大学(北京)地球物理与信息技术学院,北京100083

出　　处：《地球物理学进展》2017年第6期2430-2435,共6页Progress in Geophysics

基　　金：国家科技重大专项项目(2011ZX05040-005);河南省高校科技创新团队支持计划项目(14IRTSTHN002);河南省瓦斯地质与瓦斯治理重点实验室--省部共建国家重点实验室培育基地开放基金项目(WS2017A04)联合资助

摘　　要：近年来透射法槽波地震勘探技术在煤矿勘探领域取得广泛应用,该技术依据槽波频散特征,对特定频率下槽波走时进行层析速度反演成像,在煤层厚度探测方面效果明显.由于煤矿巷道施工的特殊性,震源和检波器布置在巷帮煤层中,观测系统多采用两边式或三边式,导致槽波传播角度有限,容易对层析成像造成误差.在层析正演中采用最短路径与射线弯曲法联合,兼顾走时计算的精度和效率,在层析反演中进行正则化约束,利用平滑和阻尼因子提高算法的精度.通过对大量模型进行正反演发现,当煤层中存在垂直巷道异常体或局部异常体时,透射槽波层析反演不存在假象;当存在平行巷道的条带异常体时,层析结果出现交叉状速度异常假象.这是由于透射槽波采集得到的走时不受异常体位置影响,高值区在平面上表现为交叉型,导致层析反演出现假象.实际勘探施工条件允许情况下,可在煤层工作面四周布置震源和检波器消除这类假象.In current years,the transmission channel wave seismic exploration has been widely applied in coal exploration. Based on the frequency dispersion characteristics of the channel wave,tomographic velocity inversion imaging of the travel time of the channel wave is conducted by this technique at specific frequencies,which has an obvious effect in detecting the coal seam thickness.Because of the particularity of coal mine roadway construction,the seismic sources and detectors are arranged in the wall of coal and the two-side or three-side systems are often used in the observation system,resulting in the propagation angle limitation of the channel wave and easily causing errors in the tomography. Combining the accuracy and efficiency of the travel time calculation,the methods of the shortest path and the ray bending are adopted in the tomographic forward. Furthermore,the regularization constraint is conducted in the tomographic inversion and the accuracy of the algorithm is improved by the smoothing and damping factors.Through the forward and inversion based on a number of models,no artifact exists in the result after tomographic inversion of the transmission channel wave seismic when there is the anomalous body vertical to the roadway or the local anomalous body,and the crossshaped velocity anomalous artifact will appear in the tomographic result when there is the banded anomalous body parallel to the roadway. This is due to the fact that the travel time acquisitioned in the transmission channel wave is unaffected by the position of the anomalous body and the high value area is cross-shaped on the plane, resulting in the artifact appeared in the tomographic inversion. If construction conditions of the actual exploration permit,this kind of the artifacts can be eliminated by making the seismic sources and detectors arranged surrounding the coal seam working face.

关 键 词：槽波 透射法 异常体 假象 层析成像 

分 类 号：P631[天文地球—地质矿产勘探]