While the UK government and operators may be looking to maximise economic recovery and fend off decommissioning for as long as possible, the winding down of exhausted assets is an inevitable task. According to the Oil and Gas Authority’s recently published Decommissioning Strategy, the current cost estimate for UKCS decommissioning to 2050 stands at between £28.2 billion and £66bn – and there are a number of new technologies jostling to become the solution to various parts of this complex and costly process.
Decom North Sea and the Oil and Gas Innovation Centre are just two of the organisations looking to ease the emergence of an efficient decommissioning market, and OGIC in particular are championing new technology and innovations to make the transition easier, safer and more cost effective.
Shell’s Brent field decommissioning project is soon to get under way, after the company announced its recommendations to the government in July, including plans to leave in place the 31,500-tonne steel jacket footings of the Brent Alpha platform and the concrete gravity base structures (GBSs), weighing 300,000 tonnes each, of the Bravo, Charlie and Delta platforms. Shell argues that the jacket and footings were never designed to be removed and that the risks involved in re-floating them would far outweigh any environmental benefits.
It is an argument that has not washed with everyone, despite the recruitment of an Independent Review Group to analyse the company’s research findings.
“Shell has clearly spent millions preparing arguments to support what they are planning to do,” Alex Russell, professor of petroleum accounting at Robert Gordon University (RGU) and chair of the Oil Industry Finance Association, told Energy Voice in an August interview.
“They have always and will always prefer to leave things in place to get things done as cheaply as possible. It’s all very well and good having these scientific reports but I don’t think they hold water.
“The technical developments we have seen mean these things can be done safely. It would cost a lot more but it also means more people being employed and the creation of spin off companies in the UK and Scotland.”
Professor Russell went on to criticise the proposals Shell has put forward to the Department of Business, Energy and Industrial Strategy (BEIS) in an article co-authored by Professor Peter Strachan – a colleague at RGU.
“[A]s demonstrated by the recent grounding of the Malta bound drilling rig Transocean Winner on Dalmore in Lewis and the consequent spillage of thousands of gallons of diesel fuel, the less distances rigs and topsides have to travel the better from a safety and environmental perspective.”
According to Russell and Strachan, the proposals contain obvious flaws, and to accept them would be a hypocritical move by the government.
“The exportable technological inventions and innovations achieved by the UK oil industry in finding solutions to previously intractable oil extraction problems is constantly trumpeted by Oil and Gas UK and by the Oil and Gas Authority as a defining feature of the industry,” their article for Oil Voice continued. “If true, this technology should be deployed, regardless of cost, to deal with decommissioning of GBSs.”
One area where the potential for innovation and competition has been repeatedly highlighted is in heavy lift vessels for decommissioning activity. The cost of hiring vessels is one of the main drivers of spend, according to analysis from Douglas-Westwood.
They anticipate that future demand from operators for single lift vessels (SLVs) to remove topsides, such as Allseas’ Pioneering Spirit, could see SLV fleet size grow as other shipbuilders compete.
Others looking to compete include Damen Shipyards Group, which announced its Decommissioning Series concept design in July, and San Diego based Seaways Engineering International. The latter is currently seeking funding for a prototype semi-submersible designed to act as a floating dry dock, effectively.
“Our vessel, which we call Nessie, is a simple floating dry dock with a modification that allows us to surround and lift structures rather than lift them from over the top, a very dangerous and limiting option,” the company’s founder, Stewart Lang told The National newspaper in early September.
“Seaways Engineering and Stewart Lang’s ideas sound like manna from heaven and must be taken into account as a benchmark for approval by the UK Government when decommissioning plans are presented for their approval,” Professor Russell commented for the same article. “They provide prima facie evidence that the technology already exists for removing safely and economically all the concrete and steel gravity-based structures that pin many oil platforms to the North Sea floor.
“This resonates perfectly with the claims of Oil and Gas UK and the Oil and Gas Authority of remarkable advances in the use of technology by the industry.
“There is huge potential for gains across the Scottish economy by deploying such technology for decommissioning and that is on top of the prize of having a debris-free North Sea for future generations to enjoy.” ■
Adjacent Oil & Gas
From Adjacent Oil & gas 5, November 2016