张量CSAMT方法及对比实验  

Tensor CSAMT technical research and experiments

作　　者：张振宇 王刚[2,3,4] 胡祥云[1] 李永博 王大勇 姚大为 

机构地区：[1]中国地质大学(武汉),湖北武汉430074 [2]国土资源部地球物理电磁法探测技术重点实验室,河北廊坊065000 [3]中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000 [4]国家现代地质勘查工程技术研究中心,河北廊坊065000

出　　处：《石油地球物理勘探》2017年第4期869-874,共6页Oil Geophysical Prospecting

基　　金：中央公益性基本科研项目"张量CSAMT三维电磁场值正演数值模拟研究"(AS2016J04);"张量CSAMT场源组合方式研究"(AS2016J03);"张量CSAMT方法技术研究与传感器研制"(12120113100800)联合资助

摘　　要：可控源音频大地电磁法(CSAMT)目前主要以标量测量为主,标量CSAMT只能在地下产生单一方向的电流矢量,只能求取标量阻抗,因此只适合一维构造及构造走向与测线垂直的二维情况。对于复杂的三维地电结构,CSAMT可采用张量测量。本文使用V8多功能电法仪进行张量CSAMT试验,发射端采用两个相互垂直的发射源,接收端采用五分量接收,数据处理采用阻抗张量分解技术,与标量CSAMT和音频大地电磁测深(AMT)结果对比,表明张量CSAMT远区数据与同测点AMT数据曲线整体形态趋势一致,重合性很好,只是天然场信号较弱,高频段AMT曲线不及张量CSAMT曲线圆滑;标量CSAMT数据与AMT数据相差很大,已经不能正确反映地下结构特征。因此,张量CSAMT可以弥补标量CSAMT适用范围的局限性和AMT信号弱、干扰大的问题。Nowadays controlled-source audio-frequency magnetotelluric method(CSAMT)carries out mainly scalar measurement,and this scalar CSAMT only produces a single direction current vector underground and calculates scalar impedance.It is only suitable for one-dimension targets or two-dimension targets in which structural trends are perpendicular to survey lines.For 3D complex structures,tensor measurement is proposed.In the paper,we use the meter V8 to carry out tensor CSAMT experiments.We record five component electrical and magnetic fields.For transmitters,we use two electrode current sources vertical each other.The impedance tensor decomposition technique is adopted at the data processing stage.The tensor CSAMT experiment results are compared with that of scalar CSAMT and audiofrequency magnetotelluric(AMT).According to the experiment results,tensor CSAMT data is generally coincident with AMT data,while AMT data are not so smooth due to its weak natural field signals.There is a big difference between scalar CSAMT and AMT data,so scalar CSAMT data cannot correctly reflect underground structures.Tensor CSAMT can overcome the scalar CSAMT limitations and AMT weak signals.Our research on tensor CSAMT may provide a good reference for petroleum geophysical exploration in the future.

关 键 词：标量CSAMT 张量CSAMT 数值模拟 阻抗张量 

分 类 号：P631[天文地球—地质矿产勘探]