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

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 similar to 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.