海洋电磁低时钟漂移及自动增益采集技术研究  

Research of low time drift and automatic gain data acquisition of marine electromagnetic

作　　者：张天信 王中兴[1] 吴树军[1] 底青云[1] 任文静[2] 叶鹏飞 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国石油集团东方地球物理勘探有限责任公司西安物探装备分公司,西安710077

出　　处：《地球物理学报》2017年第11期4165-4173,共9页Chinese Journal of Geophysics

基　　金：自然科学基金项目(41404147);中国科学院青年创新促进会;中国科学院关键技术人才项目的联合资助

摘　　要：作为地震探测的有效补充,电磁法在海洋油气资源勘探中发挥着越来越重要的作用.本文针对海洋电磁法中极低时钟误差、大动态范围采集等要求,提出使用GPS和高精度原子钟解决低时钟漂移问题;采集电路中设计增益可调的放大电路,MCU通过对采集到的信号进行实时分析,实现增益动态调整,解决海洋电磁信号大动态范围采集问题;研制的海洋电磁信号数据记录单元每天时间误差小于0.3 ms、电场通道动态范围可以达到160 dB、磁场通道动态范围可以达到134 dB.通过在室内指标测试、室外试验,表明设计的数据记录单元能够稳定可靠工作.为证明数据纪录单元的有效性,将数据记录单元和国外商用MT仪器进行野外一致性对比实验,数据记录单元与商用仪器结果基本一致;在水深100 m海域进行了海底MT信号采集,得到了有效的结果.该研究为海洋电磁信号低时钟漂移、大动态范围采集提供了一种有效解决方案.As an effective complement to seismic survey, the electromagnetic method is playing an increasingly important role in offshore oil and gas exploration. This study proposed to apply the GPS and high-precision atomic clock module and automatic gain control to meet the requirements of low clock error and large instantaneous dynamic range of acquisition. The daily time error of the developed marine electromagnetic signal data recorder unit is less than 0.3 milliseconds. The dynamic range of electric field channels can reach 160 dB and the dynamic range of magnetic field channels can reach 134 dB. Through indoor and outdoor tests, it is shown that the designed data recorder unit can work stably and reliably. In order to prove the validity of the data recorder unit, the data recorder unit and the foreign commercial MT instrument are compared in a field consistency experiment, indicating the data recorder unit is consistent with the commercial instrument results. The seafloor MT signal was collected at depth of 100 meters, and the effective results were obtained. This study has provided an effective solution for low time-drift and large dynamic range acquisition of marine electromagnetic signals.

关 键 词：海洋电磁法 数据记录单元 低时钟误差 自动增益控制 

分 类 号：P631[天文地球—地质矿产勘探] P738[天文地球—地质学]