摘要
瞬变电磁(TEM)视电阻率早、晚期计算公式在求取时进行了简化近似,造成部分地电信息的失真.瞬变电磁响应信号衰减过程与介质的电性特征有关,由此引入瞬变电磁响应微分衰减速度和二阶微分衰减速度两个解释参数,力图避开视电阻率计算,以衰减速度表示瞬变电磁探测结果的电性特征.首先研究了不同导电均匀半空间与低阻目标体地电模型瞬变电磁响应微分衰减速度在时间上的变化特征,在此基础上对瞬变电磁响应二阶微分衰减速度进行了分析,通过绘制TEM二阶微分衰减拟断面图实现了低阻目标体地电模型的电性层划分.研究结果表明:电性分界面与二阶微分衰减的"0"等值线相对应,可以用"0"值等值线作为电性分界面的划分依据,即瞬变电磁微分解释方法能够区分不同地电断面,可以用于瞬变电磁探测成果解释.
The distortion of some geoelectric information is mainly caused by our conventional habit of applying approximation in formulating the early-time and late-time apparent resistivity of TEM.However,the attenuation of ransient electromagnetic response has relation with electrical characteristics of its media.Thus,differential attenuation velocity and second-order differential attenuation velocityare introduced to avoid calculating of apparent resistivity directly with distortion.These two parameters have the ability to interpret the researching result of electrical characteristics.Firstly,time-domain variation characteristics of differential attenuation velocity in different homogeneous half-space and low resistivity zone geoelectric model TEM response,are studied.Then,on such basis,second-order differential attenuation velocity of TEM response is analyzed.The division of electric layers in low resistivity zone geoelectric model is realized through conducting pseudosection of second-order differential attenuation velocity in TEM.As is shown by the research,thezero contours of electrostatic interfaces and second-order differential attenuation velocity corresponds,proving that electrostatic interfaces can be divided on the basis of zero contours.In other words,differential attenuation integrated interpretation method in TEM is capable of distinguishing geoelectric section and explaining the results of TEM detection.
出处
《地球物理学进展》
CSCD
北大核心
2017年第4期1621-1627,共7页
Progress in Geophysics
基金
国家重点基础研究发展计划(973)项目(2013CB227900)
国家自然科学基金青年基金项目(41304113)
国家留学基金委公派留学项目(201606425004)联合资助
关键词
瞬变电磁法
微分计算
电性层
解释方法
TEM
differential calculation
electric layers
interpretation method
