High-resolution multibeam sonar for subsea leakage detection

This paper concerns detection of subsea leaks in offshore oil and gas installations by application of Multi Beam Echo Sounder (MBES) technology. Offshore recovery of hydrocarbon is carried out in still deeper waters, and in increasingly environmental vulnerable areas such as the arctic regions. Subsea leaks can occur from process infrastructure and pipelines or it can occur from the seabed itself, where reservoir instability may result in leaks. Recent catastrophic accidents within the offshore industry have lead to an increased need for monitoring subsea installations. Here, leak detection performance of the 400 kHz high resolution sonar, the Seabat 7128 forward looker, is presented. Data from an actual leaks are presented. It is shown how the sonar discovers a huge leak from a subsea reservoir. Other examples are based on small synthetic leaks established in harbors and near coastal areas. Here, detection performance is evaluated in terms of fluid leaks with varying pressure difference, orifice diameter, and range. The algorithm associated with small leaks can detect and localize a weak 5 bar fresh water flow originating from an 1 mm orifice at a distance of 75 meter. The results are followed up by a discussion on limitations and opportunities