深水拖曳式大功率时频发射与多链缆多分量电磁探测系统

High-power time-frequency transmission and multi-chain cable multi-component electromagnetic system for deep-water exploration

海洋可控源电磁探测方法是目前海洋油气资源勘探和海底地质构造调查中不可或缺的物探手段之一.本文研究的深水拖曳式大功率时频电磁发射与多链缆多分量电磁探测系统,是深水双船拖曳式可控源海洋电磁勘探系统的关键组成部分.发射系统利用深拖缆实现了电能在复杂海洋环境下长距离、大功率和低损耗传输,基于大功率变流拓扑结构攻克了2000 A量级、0.01~16 Hz可控的时频域大电流冲击脉冲发射;接收系统建立了主节点与最多5个从节点的数据链接,单个从节点记录到了三轴正交的电磁场分量以及运动姿态信息.海洋试验表明,深水双船拖曳式海洋可控源电磁勘探系统借助发射系统与接收系统之间的时间同步、时频观测、可变收发距和观测装置等技术优势,显著提升了数据质量和有效的数据数量,为后续处理和反演提供了硬件支撑.经过海上试验,整套系统的技术性能得到多次验证,未来有望在深水油气、天然气水合物和海底硫化物等资源勘查以及海底地质构造调查领域获得广泛应用.

Marine controlled-source electromagnetic(MCSEM)is one of the indispensable geophysical methods in the exploration of offshore oil and gas resources and the investigation of seabed geological structures.In this paper,the deep-water towed high-power time-frequency electromagnetic transmission and multi-cable multi-component electromagnetic acquisition system are described,which are the key components of the deep-water two-ship towed MCSEM exploration system.The transmission system realizes the long-distance,high-power and low-loss transmission of electric energy in complex ocean environment by using deep tow cable.Based on the topology of high-power converter,it overcomes the time-frequency domain high-current impulse transmission of 2000A magnitude and 0.01~16 Hz controllable frequency.The acquisition system establishes the data link between the master node and up to 5 slave nodes,and each slave node records the three-axis orthogonal electromagnetic component and motion attitude information.The offshore test shows that the deep-water dual-ship towed MCSEM exploration system significantly improves the data quality and effective data quantity,and provides hardware support for subsequent processing and inversion,with the advantages of time synchronization,time-frequency observation,variable transmit-receive distance and observation device between the transmission system and the acquisition system.The performance of the whole system has been verified many times through offshore tests,and is expected to be widely used in the exploration of deep water oil and gas,gas hydrate and seabed sulfide resources and the investigation of seabed geological structures.