【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2nV/槡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.更多还原

【Abstract】 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 2nV/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.更多还原