ABERDEEN, UK – A study will be initiated later this month aimed at providing guidance to Britain’s government on environmentally responsible methods for decommissioning offshore pipeline bundles.
ITF, the technology facilitator for the global oil and gas industry, is providing funding for the initiative. This will be led by project management and engineering consultancy PDi, with assistance from eight operating companies.
Currently, no guidance is available to the industry on decommissioning pipeline bundles.
Bundles incorporate all flowlines, water injection, gas lift, chemical injection and control systems required for a subsea development into one carrier pipe. Benefits include protection against external hazards, a reduction in the pipeline corridor, and cost savings.
Anthony Onukwu, ITF senior technology analyst, said: ““The Department of Energy and Climate Change’s guidelines for the decommissioning of offshore oil and gas installations and pipelines indicate that any new pipeline bundles should be designed for future removal. However, more than 60 pipeline bundles have already been installed in the North Sea, with an estimated combined length of 250 km [155 mi].
“Some of these are now approaching decommissioning and currently there are no guidelines on how to do this. This study should be of value to asset owners developing bundle decommissioning programs and will hopefully provide guidance for DECC and stakeholders when assessing decommissioning proposals.”
Graeme MacDougall, operations manager at PDi, said: “When it comes to decommissioning, pipeline bundles are substantially different from other pipelines and although they may appear similar to trunk lines, as they have a large diameter and sit on the seabed, unlike trunk lines pipeline bundles are all less than 7.5 km [4.6 mi] long.
“Taking into account their relatively short length, they may seem to have more decommissioning synergies with in-field lines than with trunk lines, but their large diameter generally rules out burial, refloating bundles for recovery poses significant engineering and operational challenges, and cutting it into sections for recovery will involve an extensive subsea intervention campaign and multi-handling of abnormal loads.”