A survey conducted by the University of Technology Sydney in Australia has found that leaving decommissioned oil rigs on the seabed could prove beneficial to marine wildlife.
Among 38 environmental experts polled as part of the survey, 36 agreed that a ‘case-by-case’ approach should be followed for the process of removing decommissioned oil rigs in order to benefit marine life in the North Sea.
The survey noted that more than 7,500 offshore oil and gas platforms are set to reach the end of their life, with many of them stationed in the water for around 30 years.
It argued that the platforms have provided an artificial reef for local marine life and form a part of the ecosystem in which a wide range of species thrive.
Taking this into consideration, partial removal options will offer better environmental outcomes than complete removal for platforms, according to the study.
The existing practice of removing offshore infrastructure once they reach the end of their productive lives could result in potential loss of biodiversity and destruction of seabed habitat.
Lead author of the study Dr Ash Fowler said: “These structures are huge and removing them is complex and costly. Our findings indicate that here is a big gap between existing policy and current knowledge of decommissioning impacts.”
The study was conducted to guide best decommissioning practices.
Study co-author Dr Anne-Mette Jørgensen warned that complete removal of infrastructure could lead to reopening of fishing grounds to bottom trawling, thereby proving detrimental to the wildlife.
Jørgensen said: “Bottom-trawling is a very common type of fishing and is a well-known issue in the North Sea and globally, because of its devastating impact on seabed habitat.
“The safety zones around offshore structures are some of the few areas in the North Sea, where all kinds of fishing are forbidden.”
The study made some recommendations to the existing North Sea decommissioning policy, including suspending obligatory removal of obsolete offshore infrastructure until more research into their environmental impacts is conducted, and development of a comparative assessment framework based on optimising decommissioning decisions.
The authors of the study urged operators to consider the ecosystem services provided by offshore structures prior to removal.