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研究了一种能够快速、准确、稳定的计算电性双极源频率域全区视电阻率的方法并分析了应用效果.首先研究了均匀半空间上双极源频率域电磁场和大地电阻率的关系,得到电场水平方向分量(E_x)、阻抗(Z_(xy))是大地电阻率单调递增函数的结论,结合二分法的思想,把求取全区视电阻率的过程当作一个用二分法对非线性方程求根的过程,利用二分法对理论模型数据计算了E_x和Z_(xy)定义的全区视电阻率,并与卡尼亚视电阻率进行了对比,结果表明计算得到的全区视电阻率不受过渡带影响,较真实客观的反映了地电断面的电性变化;对理论数据加入随机噪声后,E_x定义的全区视电阻率对干扰的抑制最大,Zxy定义的全区视电阻率及卡尼亚视电阻率对干扰的抑制较弱.对某工区实测CSAMT和AMT数据处理结果表明,全区视电阻率对CSAMT方法的非平面波效应有很好的改善作用,利用CSAMT全区视电阻率探测1 km范围以内的地质构造具有分辨率高、保真度高、不受过渡带和近区场影响的特点,证明CSAMT全区视电阻率方法可进行大深度第二空间找矿勘探的结论.
A method to calculate the apparent resistivity in the frequency domain of an electric dipole source quickly, accurately and stably was studied and the application effect was analyzed.Firstly, the electromagnetic field and the resistivity of the dipole source in a uniform half-space were studied (E_x) and impedance (Z_ (xy)) are the monotonically increasing functions of the earth resistivity. Combining with the idea of dichotomy, the process of determining the apparent resistivity of the whole area is taken as a dichotomy In the process of rooting the nonlinear equations, the apparent resistivity of the whole area defined by E_x and Z_ (xy) was calculated by the dichotomy method and compared with the Karniyes resistivity. The results showed that the calculated total area The apparent resistivity is not influenced by the transition zone, which reflects the electrical change of the geoelectric section more objectively and objectively. After the random noise is added to the theoretical data, the apparent resistivity of the whole area defined by E_x has the largest inhibition on the interference. The Zxy defined whole area The apparent resistivity and Karnaugh’s apparent resistivity show less inhibition on the interference.According to the measured CSAMT and AMT data in a certain area, the apparent resistivity of the whole area has a good improvement on the non-plane wave effect of the CSAMT method, and the CSAMT The geologic structure within 1 km of area apparent resistivity detection has the characteristics of high resolution, high fidelity and not affected by the transition zone and the near field. It is proved that the CSAMT whole area apparent resistivity method can be used to find the deep second space Mine exploration conclusion.