Leak Detection from SONASEARCH
Doppler-based leak detection and flow rate

The need to have a robust toolset for early detection of hydrocarbon leaks - or to mitigate against the adverse effects a thermal leak can have to the flow assurance of a pipeline - is clear.

Gas leaks, petroleum product leaks and hot water plumes associated with degraded pipeline insulation all create acoustic impedance interfaces in the fluid that can create acoustic reflections. The fluid-gas interface of gas bubbles generally produces strong reflections and can generally be easily detected by acoustic systems. The liquid-liquid interfaces associated with liquid petroleum product leaks produce much lower reflections intensities but have been shown in initial, open water testing to be clearly detectable even at significant ranges with acoustic systems using phased-array, beamformed technology. In addition, even the subtle liquid-liquid thermal interfaces associated with hot water plumes have been shown to be detectable in a controlled tank test environment. Likewise initial tests into acoustic Doppler measurements from Acoustic Camera™ technology indicate that in-plume velocity measurements combined with cross sectional images of hydrocarbon plumes could yield accurate estimates of volumetric flow rate useful in assessing the dynamic impact of a detected flow assurance event.

The leak detection capabilities embodied in Sonasearch Acoustic Camera technology are capable of being deployed using automated detection in the following scenarios:

• As part of an ROV based equipment spread with background routines designed to flag events using gated alarm criteria related either to the pipe itself or far field events either side of the pipeline route.
• As part of an AUV or glider solution capable of covering wider areas in search of natural hydrocarbon seeps or integrity concerns related to installed subsea infrastructure.
• As a stand-alone node used to monitor a critical piece of subsea jewelry for extended periods e.g. a subsea BOP, XMAS tree or subsea processing facility such as a separator.
• As part of a nodal network designed in at FEED stage and aimed at long term monitoring of a wider area.