摘要
常规的可控源电磁法理论在计算视电阻率公式上,由于主要采用了其电磁场,所以难以直接反映全频域视电阻率的值,也不能直观地显现出地下介质的地质构造。这里采用水平偶极子激发的电磁场,提出了电场的全域精确表达式,并可直接计算出大地电阻率。通过与卡尼亚电阻率计算的对比结果表明:该方法的结果在远区等价于卡尼亚电阻率,在近区和过渡带则明显地改善了卡尼亚电阻率的非波场区场畸变,从而能更好地接近基底的真电阻率,更形象地反映了地下介质的垂向电性变化。
The electromagnetic theory of conventional CSAMT mostly adopts its approximate characteristic on calculating the apparent resistivity,the method is difficult to reflect directly resistivity value in full-frequencies and show subsurface geological structure directly.The paper presents a new full-domain expression of electrical field to calculate directly and accurately the earth resistivity by using the electromagnetic fields from horizontal electric dipole.The results show that the results from our method are equal to Cagniard resistivity in far-field,but our method has greatly improved the strong distortion of Cagniard resistivity in near-field area and transition area.So the results can reach the true resistivity of basement and indicate the change of subsurface conductivity much better than Cagniard resistivity does.
出处
《物探化探计算技术》
CAS
CSCD
2009年第3期210-212,共3页
Computing Techniques For Geophysical and Geochemical Exploration
关键词
CSAMT
卡尼亚视电阻率
全域视电阻率
近场效应
计算方法
CSAMT
Cagniard resistivity
full-domain apparent resistivity
near-field effect
calculation method
