利用积分方程法研究复杂三维地质结构CSAMT响应特征

CSAMT response of 3D geological structure model using ntegral equation method

由于复杂三维异常体模型与实际的地质结构更为接近,研究复杂地质结构的物理性质逐渐成为研究的热点.CSAMT三维模拟中,积分方程法因只需要对异常区域进行离散,具有占有内存少,运算速度快等优点.为了解复杂三维地质结构的CSAMT响应特征,本文先设置围岩为花岗岩体的含有倾斜断层等构造的三维复杂模型,利用积分方程法对它进行正演模拟并对模型的CSAMT响应特征进行分析.发现当异常体在垂直于测线方向的尺度发生变化时,在不同测线上观测的响应特征有所不同,进一步说明如果需要提高资料的解释效果,需要做三维勘探.最后基于油气藏电性结构特征,设置了含油构造的层状模型并进行正演模拟运算,含油构造模型的CSAMT响应特征表明,电性结构异常体的存在对电场的影响比对磁场的影响更敏感,这为我们以后的资料解释工作提供了最好采用电场总场资料而不用磁场总场资料的理论依据.

As the complicated 3D Model is more similar with actual geological structure,analyzing the physical properties of complicated geological structure has become a hot research topic recently. On CSAMT 3D simulation,the Integral Equation Method only discrete the anomalous area with fast operation and occupy less storage. In order to understand the CSAMT characteristics of complicated geological structure, in this paper we firstly simulated the controlled-source audio-frequency magnetotellurics（ CSAMT）response of potential radioactive waste disposal rocks by using Integral equation method. We found that the 3D prospecting should be considered if there was a 3D anomalous target body in the survey area, because the CSAMT response is different on different measuring line. Then we made an oil-bearing model based on the electrical structure of oil reservoir and simulated the CSAMT effect of that model. CSAMT response indicated that we should use total electric field in data interpretation, because the existence of electrical anomalous target had more sensitive effect on total electric field than total magnetic field.