DECOMMISSIONING projects require meticulous study, planning, engineering and approval prior to execution. The lead time to execution is quite often long and needs to be factored into considerations well before the asset reaches the end of its service life.
“Given the age of assets and the gradual depletion of older fields in Australia it is expected that preparation for decommissioning of economically marginal opera tions will begin to increase in the coming years,” says Matt Gavin, PSN general manager Australia.
PSN has been awarded a contract by Shell UK (Shell), acting on behalf of itself and Esso Exploration and Production UK (Esso), for work on the Brent oil and gas field in the UK North Sea.
“One critical skill for any contractor managing a decommissioning project is superior planning capabili ties,” notes Gavin. “When assets are ‘destructed’ the work environment changes rapidly, for example escape routes change as kit and structures are removed and significant volumes of debris must be cleared from the work site.” A thorough planning process is required to manage these challenges successfully. Unlike during construction where there is a pre-determined erection sequence, during decommissioning more contingencies must be planned for from the outset, recognising all the constraints that working on an asset that is probably more than 50 years old may impose.
“In addition, the hazards (such as sludge, asbestos and other elements) can be uncovered in the process and must be dealt with in orderly and safe manner and with absolute professionalism and rigour,” Gavin told PACE. The general skills of integrated planning and dynamic safety management involved in decommis sioning are extensions of what many contractors oper ating in Australia currently do. “However, Australia has very few contractors who are focused on the brownfield side of the market. I believe it is an essential require ment for any successful decommissioning contractor to have an established pedigree in brownfield works, as this gives the asset owner confidence that the contractor has the requisite skills to work in confined spaces, on pressurised systems, with toxic materials,” says Gavin.
PSN’s Shell contract is for the decommissioning services on the Brent Delta platform topsides. PSN will provide services including integrity management; module, process and utility separation; safe shutdown; hydrocarbon cleaning; disconnections and preparation for removal of the topsides. Offshore work is expected to begin around late 2011 as part of the initial stages of Brent Delta decommissioning.
The regulations for decommissioning in Australia are broadly consistent to those that operate in the UK. “However, as the requirement for offshore decommis sioning is more current in the UK, the regulations are generally more bedded down in the UK in this space,” notes Gavin.
Elements relating to the regulatory system for decommissioning works in Australia include the Petroleum (Submerged Lands) Act as well as the rele vant sections of environmental regulation of sea dumping and biodiversity. In addition there are Australia’s international commitments, such as the United Nations Convention on the Law of the Sea and the guidelines provided by the International Marine Organisation. The UK shares many of these interna tional responsibilities. “A difference is that the UK also faces obligations as a party to the Convention for the Protection of the Marine Environment of the North- East Atlantic — the ‘OSPAR Convention’,” says Gavin.