摘要
对大地介质影响下地-井瞬变电磁响应特征规律进行了研究.基于时域有限差分法和Mur吸收边界条件对不同观测方式("定源-异井位观测"和"方位观测")下典型地电模型(均质半空间和含浅部低阻层的半空间介质)中三维体的地-井瞬变电磁响应进行了正演模拟,认为观测所得响应是围岩背景场与目标体异常场共同作用的结果,提出大地介质会影响观测结果的观点.研究结果表明:围岩背景场越强,总响应的异常特征越弱;随着观测延时的增加,背景场对总响应的影响减弱;受导电介质影响的观测曲线在剖面形态和衰减特征上与高阻围岩的典型解释模型存在差别.研究结果为相关资料解释工作提供了理论依据.
The regularity and characteristics of the surface-borehole transient electromagnetic method(TEM)response considering the geological medium effect was investigated.The surface-borehole TEM responses of a three-dimensional conductive plate in a typical half-space model,including a uniform half-space model and an additional model with a conductive overburden,were simulated to obtain results for a 'fixed source survey at different hole' and ' direction survey' using the finite-difference time-domain method and Mur absorbing boundary condition.The survey response was found to be related to the anomalous electromagnetic field of the local conductor and the background electromagnetic field of the geological media,and it is proposed that surface-borehole TEM response is affected by the geological medium.The results show that the background field of the medium was stronger,the anomaly characteristics of the total response increasingly weakened,and the effect of the background field decreased with an increase in observation time delay.Compared with the typical interpretation model ofahigh resistivity medium,the responses considering the medium effect differ in profile and attenuation characteristics.These research results provide a theoretical basis for interpretation work of related data.
出处
《中国矿业大学学报》
EI
CAS
CSCD
北大核心
2014年第6期1113-1119,共7页
Journal of China University of Mining & Technology
基金
国家自然科学基金项目(41304082)
河北省自然科学基金项目(D2014403011)
关键词
地-井瞬变电磁
井中瞬变电磁
回线源
三维正演
时域有限差分
surface-borehole TEM
borehole transient electromagnetic method
loop source
three-dimensional forward
finite difference time domain method
