巷道CSAMT法的目标体分辨能力研究

Research on resolving ability of deep subsurface targets from mine roadway using CSAMT method

目前地表矿、浅部矿越来越少,寻找深部盲矿体变得尤为重要.可控源音频大地电磁法(CSAMT)具有抗干扰能力强、分辨率高等特点,在探测矿产资源中已经取得了较好效果,但是通常CSAMT在矿区找深部矿时,由于在巷道上方的地表接收电磁信号会受到地面不同类型的强电磁干扰,同时由于该方法对深部矿体分辨率较低的缘故,大大影响了CSAMT的应用效果.本文尝试将CSAMT的接收系统置于巷道中,使得接收系统更加接近地下目标体,期望提高对于目标体识别的准确性,保证资源勘查的工作效率和成功率.基于积分方程法对不同类型地质模型进行了CSAMT正演模拟,并对不同模型不同深度接收的CSAMT响应特征进行了分析,同时以MARE2DEM软件模拟的二维模型响应加以验证积分方程结果的正确性.结果表明在无电磁干扰条件下,在巷道接收到的电磁场信号虽弱于地面,但其对于深部盲矿或目标体具有较强的识别度.

The rapid development of Chinese economy has led to increase in the demand for mineral resources,while surface and shallow minerals are currently decreasing.Therefore,it is important to explore for new blind ore bodies at depth.The Controlled Source Audio-frequency Magnetotelluric Method(CSAMT)has been highly effective in geophysical prospecting with wide detection range and high resolution.However,CSAMT prospecting for deep subsurface mineral resources in mining areas is subjected to different types of strong electromagnetic interference.Due to the limitation in data resolution at depth,the effective application of CSAMT in miningareas is greatly affected.To solve this problem,this work attempts to place the CSAMT acquisition array system in the roadway,making the receiver system closer to the underground target or passing through different geological boundaries.The proposed array is expected to improve the accuracy of target identification and increase the efficiency and success rate of deep resources exploration.The forward modeling of different types of geological bodies based on the integral equations,and analysis of the CSAMT response characteristics for the different models at different depths are performed.The results obtained from the integral equations are validated by two-dimensional modeling results from MARE2 DEM.The results show that in anoise-free environment,although the electromagnetic field signal received in the roadway is weaker than that recorded on the surface,its resolution to the deep blinded ore body or target is better.