Simultaneous Subsea Gas Plumes Detection and Positioning Using a Transceiver of an Ultra-Short Baseline System

This paper presents an in-situ active acoustic detection system that can detect and locate the subsea gas plumes simultaneously using a transceiver of an ultra-short baseline (USBL) positioning system. Seabed gas leaks, both natural and artificial, are causing concern worldwide. Conventional detection systems, including Raman spectrometers, side-scan sonars, and multibeam sonars, suffer from some limitations such as the effective range and real-time processing problem. We use an omnidirectional USBL transceiver to illuminate surroundings and detect echoes from gas plumes. A small hydrophone array in planar circular shape is used to beam-form the received echoes. An echo identification algorithm is proposed to separate the echoes from fixed objects and gas plumes. The results are verified against various experiments. The matched filtering and phased-array beamforming are applied to determine the relative distance and angle of arrival from gas plumes. A preliminary result on gas flow rate quantification is also studied. This paper describes the system design and algorithms in detail and presents experimental results in an anechoic tank, demonstrating the great potential of this system for subsea gas plumes detection and positioning.