摘要
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.
This paper aims at studying a fast,accurate and stable calculating method of electrical bipolar source full-zone apparent resistivity in frequency domain and its application. Firstly,for a bipolar source on the homogeneous half space, the relationship between its electromagnetic fields and earth resistivity in frequency domain has been studied, the conclusion has been drawn that horizontal component of electrical field（ Ex） and impedance（ Zxy）are increasing monotonous functions of the earth resistivity. Based on the bisection method,calculating process of full-zone apparent resistivity can be regarded as a process of solving nonlinear equations using bisection method,by the bisection method,fullzone apparent resistivity defined by Exand Zxy of theoretical models are calculated and compared with Cagniard apparent resistivity,results show that transition zone has no effects on calculated fullzone apparent resistivity which is more really and objectively reflected electrical changes; After theoretical data added random noise,the noise suppression of full-zone apparent resistivity defined by Ex is the largest,the noise suppression of full-zone apparent resistivity defined by Zxy and Cagniard apparent resistivity is weaker. After processing CSAMT and AMT data,conclusion has been drawn that full-zone apparent resistivity has a good effect on improving non-plane wave effect of the CSAMT and using CSAMT full-zone apparent resistivity to survey 1 km geological structures has characteristics of high resolution,high fidelity and no influence on transition zone and near zone; it is proved that the method of CSAMT full-zone apparent resistivity can be used for prospecting deep space II.
出处
《地球物理学进展》
CSCD
北大核心
2016年第4期1575-1582,共8页
Progress in Geophysics
关键词
电性双极源
CSAMT
频率域
单调性
全区视电阻率
二分法
electrical bipolar source
CSAMT
frequency domain
monotonicity
full-zone apparent resistivity
bisection method
