海底表面磁源瞬变响应建模及海水影响论述.pdf

刘长胜 , 林　君.海底表面磁源瞬变响应建模及海水影响分析.地球物理学报 , 2006 , 49(6):1891～ 1898 Liu C S , Lin J.Transient electromagnetic response modeling of magnetic source on seafloor and the analysis of seawater effect.Chinese J. Geophys.(in Chinese), 2006 , 49(6):1891 ～ 1898 海底表面磁源瞬变响应建模及海水影响分析 刘长胜 , 林　君 吉林大学地球信息探测仪器教育部重点实验室 ,长春　130061 摘　要　根据电磁场理论 ,推导了磁偶源和接收点均位于海水中时层状海底模型的频域电磁场响应一般表达式 , 并通过此式 ,得到了海水为均匀半空间和有限海水深度两种情况下 ,垂直磁偶极装置 、中心回线和重叠回线分别置 于均匀半空间海底表面时的瞬变电磁响应(磁场和感应电压)表达式.这些表达式将瞬变响应和海底的电导率等参 数有机联系在一起 ,为海底瞬变电磁法的正演计算和反演解释提供了理论基础.仿真计算表明 , 海水的存在不仅使 得瞬变响应曲线形态发生变化 ,而且影响其对海底电导率的分辨能力. 关键词　海底 ,瞬变电磁法 , 垂直磁偶极装置 ,中心回线 , 重叠回线 , 电磁场 ,瞬变响应 文章编号　0001-5733(2006)06-1891-08 中图分类号　P631 收稿日期2006-03-13 ,2006-07-31 收修定稿 基金项目　国家高技术研究发展计划(863计划)(2002AA615030)资助. 作者简介　刘长胜 ,男 , 1979年生 ,博士生 ,主要从事瞬变电磁探测方法和数据处理解释方面的研究.E_mail:liucs_15@ Transient electromagnetic response modeling of magnetic source on seafloor and the analysis of seawater effect LIU Chang_Sheng , LIN Jun Key Lab of Geo_Exploration and Instrumentation , Ministry of Education , Jilin University , Changchun 130061 , China Abstract　By electromagnetic theory , for the case that the magnetic dipole source and the receiver are set in seawater , the general expressions of frequency_domain electromagnetic responses for a layered benthal model are deduced.From those , the transient response expressions of three common configurations—vertical magnetic dipole_dipole(HZHZ), central loop , and coincident loop , located on the surface of uniform half_space seafloor , are derived respectively , supposing that seawater is uniform half space , or its depth is finite.These expressions connect transient response with oceanic parameters such as the conductivity of the seafloor , and provide theoretical foundation for forward modeling , and inversion and interpretation in seafloor transient electromagnetic exploration.The modeling indicates that the presence of seawater not only changes the shape of transient response curve , but also reduces the resolution to seafloor conductivity