STATS Group in collaboration with Paradigm Flow Services and Halliburton isolated, de-oiled, plugged and abandoned two 3.5” subsea flowlines as part of the Murchison decommissioning project.
After nearly 30 years of operation in the Northern North Sea, the CNR International operated Murchison field had reached the end of its production life.
STATS Group was initially approached to review the requirement for subsea hot tapping operations. However, following collaborative discussions with Paradigm Flow Services and Halliburton, an alternative solution that would mitigate a diver-intensive operation was proposed that could be completed solely from the platform topsides.
In order to de-oil and abandon the subsea flowlines, full bore access was required in order to install Paradigm’s Flexi-Coil technology prior to pumping Halliburton’s Thermatek fluid system. As there was no suitable valves to offer a positive isolation or provide an access point to gain entry to the flowline, STATS utilised their patented hot tap installed BISEP® isolation tool.
Dale Millward, director of EPRS and subsea services for STATS Group, said, “As a result of this collaborative project, the industry now has, where the field layout allows, a practical and cost-effective topsides solution for the isolation and abandonment of live or contaminated subsea flowlines. Unlike traditional techniques, this approach does not require a subsea intervention, eliminating the requirement for costly diving support vessel or work-class ROV vessels.”
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