隐伏构造的MT二维联合正演与分析  

Forward Simulation and Analysis of 2-D Magnetotelluric Method for Hidden Structures

作　　者：杨天春[1] 王燕龙[2] 冯建新[1] 王世党[1] 张辉[1] 

机构地区：[1]湖南科技大学土木工程学院,湖南湘潭411201 [2]黄河勘测规划设计有限公司工程物探研究院,河南郑州450003

出　　处：《新疆石油地质》2013年第6期697-701,共5页Xinjiang Petroleum Geology

基　　金：湖南省自然科学基金项目(12JJ3035);湖南省科技计划项目(2011SK3195)

摘　　要：由于隐伏断层构造模型的地电结构比较复杂,其大地电磁法的视电阻率收敛于地下真实电阻率的速度会直接影响正演结果的精度。运用大地电磁阻抗相位和视电阻率对隐伏断层构造进行正演模拟研究,采用有限单元法对常见的隐伏断层构造模型进行大地电磁正演模拟与分析,除模拟计算出各个模型的视电阻率外,还利用阻抗值获得各频点下的相位值,再对TE和TM极化模式下阻抗相位和视电阻率的正演结果进行分析。模拟结果表明,当地层电阻率由上到下变小时,阻抗相位表现为小于45°,电阻率变大时,表现为大于45°;阻抗相位也可以表征地下电性的变化特征,其敏感度比视电阻率高,从阻抗相位拟断面图可以分辨出隐伏构造体的类型。Because of the complexity of hidden geological structures and their apparent resistivity＇ s convergent rate of magnetotellurie （MT） method to true resistivity having influence on simulation precision, this paper makes the forward simulation of impedance phase and apparent resistivity of MT method for hidden faults. The finite element method is used to simulate hidden faults＇ MT anomalies.The appar- ent resistivity and impedance phase of models are calculated, and then the forward modeling results of transverse electric mode and trans- verse magnetic mode are analyzed. The simulation results show that the impedance phase is less than 45° when resistivities decrease with depth, and the impedance phase is bigger than 45° when resistivities increase. Also, the impedance phase can represent the electric charac- teristics of underground media, and its sensitivity is higher than the apparent resistivity. At the same time, the type of hidden geological structure can be distinguished from pseudo-sections of impedance phase.

关 键 词：大地电磁 阻抗相位 有限单元法 隐伏地质构造 正演模拟 

分 类 号：TE112.4[石油与天然气工程—油气勘探]