海洋拖曳式水平电偶源数值模拟与电场接收机研制  

Numerical simulation and electrical field recorder development of the marine electromagnetic method using a horizontal towed-dipole source

作　　者：陈凯[1,2] 景建恩[1,2] 魏文博[1,2] 盛堰[3] 罗贤虎[3] 陈光源[1,2] 史心语 

机构地区：[1]中国地质大学(北京),北京100083 [2]地下信息探测技术与仪器教育部重点实验室,北京100083 [3]广州海洋地质调查局,广州510760

出　　处：《地球物理学报》2013年第11期3718-3727,共10页Chinese Journal of Geophysics

基　　金：国家863计划项目课题(2006AA09A201、2009AA09A201);中央高校基本科研业务费项目(2652011260、2652011249)等联合资助

摘　　要：海洋天然气水合物资源调查中,电磁法已成为地震勘探最有效的补充手段之一,而我国海洋水合物电磁探测中的拖曳式电场接收机此前是空白.本文从方法原理、仪器设备和海洋试验等方面,对海洋拖曳式水平电偶极偶极方法进行研讨.建立三维电阻率模型,进行数值模拟,讨论收发距、发射频率、拖曳装置离海底高度等参数与电场异常响应的关系,针对特定模型给出了最佳观测参数以指导仪器硬件设计与海洋测试.在此基础上,采用高级嵌入式计算机的智能化控制、前端低噪声斩波放大、高精度同步采集等技术,研制了由拖体、承压舱、采集电路、低噪声电场传感器等组成的海洋拖曳式水平轴向电场接收机,其系统噪声达到2 nV/（√）Hz@（1～100Hz）.将自主研制的电场接收机用于国内首次拖曳式电偶极-偶极方法的海洋试验与评估,并对海试资料进行了处理与分析.研究结果表明,所研发的仪器达到了设计指标,能够用于海洋天然气水合物调查.The marine electromagnetic method has become one of the most effective supplementary methods in marine seismic exploration for gas hydrate resources,while it is a blank in the research of the towed electrical field recorder of marine hydration source exploration in our country.This paper focuses on studies of the marine electromagnetic method with horizontal towed dipole-dipole from the aspects of the principle,equipment and marine tests.Based on the constructed 3-D resistivity model and numerical simulation results,the relationship is discussed between field source parameters （distance between transmitter and receiver,transmission frequency,height from dragging device to the seafloor） and the abnormal electrical field.According to the specific model,the best field source parameters used to guide the equipment hardware design and marine tests are also decided.On this basis,a marine towed electrical field recorder is developed with use of techniques like advanced embedded MCU,lownoise chopper pre-amplifier and high-precision synchronal acquisition.The recorder is mainly comprised of a dragging device,pressure case,acquisition circuit,and low noise marine electrical field sensors.The system noise measured is about 2 nV/（√）Hz@（1 ～ 100Hz）.Then,the electrical field recorder developed independently by ourselves is applied to the first marine test in China.And the acquired data have been processed and analyzed.The results show that the recorder has achieved the designed target and can be used in marine hydrate survey.

关 键 词：海洋电磁法 数值模拟 海洋拖曳式水平轴向电场接收机 低噪声斩波放大器 海底电场传感器 

分 类 号：P631[天文地球—地质矿产勘探]