Detection of underwater gas leaks with time reversal acoustic signals

In this report, temporal and spatial focusing properties of time-reversal mirrors are studied for leakage detection. The acoustic remote sensing of subsea gas leakage traditionally uses sonars as active acoustic sensors and hydrophones picking up the sounds generated by a leak as passive sensors. When gas leaks occur underwater, bubbles are produced and emit sound at frequencies intimately related to their sizes. Two factors: the local character of the acoustic emission signal caused by the leakage and a resonant nature of the bubble radiation at their birth make particularly effective use, for active location, time-reversed emission signals in order to obtain a powerful scattering signal. The propagation of emission and time-reversed signals is described in terms of Green’s function of the Pekeris waveguide. This study expands the range of applications that use the mechanism of time-reversal focusing to specific conditions – the vicinity of drilling platforms located on the sea shelf.