海洋磁性源瞬变电磁探测系统姿态变化影响研究  

Attitude effect on marine magnetic source TEM detection system

作　　者：赵越[1,2] 许枫 曹华科[3,4] 刘佳 ZHAO Yue;XU Feng;CAO Huake;LIU Jia(Institute of Acoustics,Chinese Academy of Sciences,Beiing 100091,China;Beijing Engineering Technology Research Center of Ocean Acoustic Equipment,Beijing 100091,China;School of Geological Engineering and Geomatics,Chang’an University,Chang'an University,Xi'an,Shaanxi 710054,China;Integrated Geophysical Simulation Lab of Chang’an University(Key Laboratory of Chinese Geophysical Society),Xi'an,Shaanxi 710054,China)

机构地区：[1]中国科学院声学研究所,北京100091 [2]北京海洋声学装备工程技术研究中心,北京100091 [3]长安大学地质工程与测绘学院,陕西西安710054 [4]长安大学地球物理场多参数综合模拟实验室,陕西西安710054

出　　处：《石油地球物理勘探》2022年第5期1228-1240,I0011-I0012,共15页Oil Geophysical Prospecting

基　　金：国家自然科学基金项目“基于瞬变电磁反演的浅海掩埋小目标探测方法研究”(61801470);中国科学院青年创新促进会基金(2020023)联合资助。

摘　　要：近年来,随着海洋油气资源开发和利用的逐步深入,海洋磁性源瞬变电磁法得到广泛应用。在实际数据采集中,由于海底环境、洋流、航速不均等因素的影响,发射与接收回线装置在海水中的姿态难以保持稳定。探测系统姿态变化会导致收、发回线装置与海底电性异常体的耦合关系发生变化,观测数据出现较大误差,影响解释结果的可靠性。为此,首先基于电磁场基本理论推导了有限水深条件下海底各向同性水平层状介质模型中任意磁偶极源频率域三分量电磁场表达式,基于电磁场叠加原理分析了海洋磁性回线源电磁响应特征;其次,针对姿态变化前、后分别定义两类坐标系及相关的发射、接收双旋转矩阵,建立了水下拖曳式磁性源姿态变化的数学模型;最后,以浅海拖曳式中心回线瞬变电磁探测系统为例,通过模型算例分析收、发系统姿态变化引起的观测数据误差分布特征,及瞬变电磁响应结果与姿态变化角度、衰减时间、海水深度、海底沉积层电性等参数之间的关系。研究成果有助于量化海洋磁性源瞬变电磁探测系统的参数设计,为该方法的推广及数据的处理、解释提供理论基础。As marine oil and gas resources continuously develop,marine magnetic source transient electromagnetic(TEM)systems have drawn more and more attention in recent years.However,a stable attitude of transceiver loop devices is difficult to maintain in seawater during practical data collection due to the factors such as seabed environment,ocean currents,and uneven speed.The attitude changes of detection systems will alter the coupling between transceiver loop devices and underwater electrical anomalous bodies.This will lead to a certain deviation of observation data and reduce the reliability of interpretation results.First,based on the theory of electromagnetic field,this paper derives the three-component electromagnetic field expression in the frequency domain of arbitrary magnetic dipole source in the isotropic horizontal layered medium model under limited water depth.Then,the electromagnetic response characteristics of the marine magnetic loop source are analyzed by the superposition principle of electromagnetic fields.Second,by defining two coordinate systems and their transceiver rotation matrix before and after attitude change,the paper builds a mathematical model of attitude changes in underwater towed magnetic source.Finally,taking the towed central loop TEM detection device in shallow water as an example,it analyzes the error distribution of observation data caused by the attitude change of the transceiver system.Additionally,the relationship between TEM response results and parameters of attitude change angle,attenuation time,sea depth,and seabed conductivity is also explained.The research results can help quantify the parameter design of the marine magnetic source TEM detection system and provide a theoretical basis for promoting and processing this method in the future.

关 键 词：海洋瞬变电磁法 磁性源 姿态变化 磁偶极子模型 

分 类 号：P631[天文地球—地质矿产勘探]