A Novel Technology to Efficiently Detect Hydrate Formation in Subsea Flowlines

Abstract The objective of the R&D project and subsequent field testing was to develop, test and commercialize a new technology with an emphasis on scanning speed for use in subsea flowlines to detect hydrate plugs through thick subsea coatings without the need for 360-degree access of the pipe. Acoustic Resonance Technology has proven to be an extremely reliable and accurate way to measure wall thickness of coated flowlines and risers with insulations thicknesses of 90+ mm. While advancing the use of Acoustic Resonance Technology for pipe-in-pipe applications, it was theorized that the resonant frequencies would be able to detect the unique acoustic signature of hydrate formation within a pipe. The client initiated an R&D project to test the use of Acoustic Resonance Technology on hydrate formations in a lab setting. The testing showed a clear indication of hydrate acoustic signatures while only needing access to the top half of the pipe. The client moved to a field test on a 12 km flowline off the coast of Angola. The offshore field test was completed on an 8-inch 3-Layer polypropylene (3LPP) coated water injection line at a water depth of 1,300 m off the west coast of Angola. The tool scanned 12 km of pipe within 33 hours and identified the length of the hydrate plug. A second tool was launched to complete a 360 degree scan to define exact start and end points of the hydrate plug. Client achieved a significant cost savings compared to comparable methods due to inspection speed and a reduction in pre-inspection dredging time. This paper will show how field proven technologies, in particular Acoustic Resonance Technology, can be adapted for new uses within the subsea industry. The testing and field work shown in this paper will provide evidence of a faster and more efficient way to detect and measure hydrate formations compared to existing technologies on the market.