The New Progress in Near-surface Seafloor Exploration by Transient Electromagnetic Method

摘要

Transient electromagnetic method has been used to investigate the conductivity of seafloor since late 20th century. When the exploration was done, two antennas of large separation distance were placed over seafloor, and the step response is measured. In this paper, we study the exploration of seafloor conductivity by measuring the inductive voltage of receiver loop, which is the time derivative of step response. A configuration of central loop is used. Its transmitter loop is small and a smaller receiver loop is placed in the center. An instrument system which can be put into water and controlled from the computer on ship is developed for the exploration. Because the configuration is small and part function of the instrument system is specially designed for measurement during moving, high efficient, towed exploration can be easily achieved. Finally, an experiment of seafloor exploration was performed in Hulu Island, Liaoning province, and two oil pipelines are found.