可控源音频大地电磁法在复杂地形山区寻找煤系地层中的应用

Application of Controlled-Source Audio Magnetotelluric Sounding Method in Searching Coal-bearing Strata in Complex Terrain Area

研究区处于闽西南凹陷带的大田—龙岩凹陷,地形条件复杂,煤矿资源较为丰富且煤系地层埋深较深,常规的地球物理方法无法满足勘探要求。可控源音频大地电磁法(CSAMT)具有勘探深度大、分辨率高和受高阻屏蔽作用小等优点,在勘探工作中发挥了重要作用。可控源音频大地电磁法数据经过处理和反演,结合研究区地质资料与物性参数,可以消除地形影响,正确划分区内地层,揭露了地下岩体及构造的电性特征;依据圈定的电阻率异常可以有效地指导钻孔布设与实施。通过钻探验证,证实了可控源音频大地电磁法在复杂地形条件下寻找煤系地层的有效性,为今后复杂地形区域的深部找煤提供了指导和借鉴意义。

The study area is in Datian-Longyan depression zone in the southwestern 0 f Fujian,which has complex topographic conditions, Coal resources are abundant and coal measures strata are deeply buried. Conventional geophysical methods can not meet the requirements of exploration. Controllable Source Audio Magnetotelluric Method(CSAMT) plays an important role in this exploration because of its advantages of large exploration depth, high resolution and low resistance shielding. By standard data processing and inversion, combining with geological data and physical parameters of the study area,terrain impact can be eliminated,we divided the strata in the area, and revealed the electricity characteristics of underground rock mass and structure. the resistivity anomaly zones delineated,guided the drilling design effectively.By the application of Controllable Source Audio Magnetotelluric Method(CSAMT) and borehole verfication, the effectiveness of CSAMT in searching coal measures strata under complex topographic conditions is verified, which provides guidance and reference for deep coal exploration in complex topographic areas in the future.