North Sea oil spill risk as companies leave hundreds of old wells unplugged

Hundreds of disused North Sea oil and gas wells must be urgently filled with cement and made safe, the regulator has told offshore energy companies.

The North Sea Transition Authority (NSTA) has written to the UK’s offshore oil and gas producers after finding they have left more than 740 disused wells without decommissioning them properly. A further 2,100 wells will need decommissioning over the next decade.

Pauline Innes, the NSTA’s director of decommissioning, wrote: “I am concerned at the number of deferrals … it is apparent that a considerable number of well decommissioning activities – most of which have been deferred previously and which licensees had committed to execute in 2023 – may not be undertaken before the end of this year, and I note that more deferrals are already being sought.”

Oil is a marine toxin and methane is a very powerful greenhouse gas. A single unplugged or badly plugged borehole can release tonnes of methane a year so inactive ones are meant to be plugged with cement within two years.

However, plugging old wells typically costs £8m a time, money many oil and gas companies are increasingly reluctant to spend. The growing backlog has prompted fears that some operators will quit the UK or go out of business, with taxpayers forced to pick up the final bill.

The NSTA’s latest Wells Insight report said the number of inactive wells needing to be properly decommissioned was at an “historical high” of 30pc, three times higher than the limit set by the regulator.

The NSTA’s list of the owners of inactive wells includes most of the UK’s offshore operators including TotalEnergies, BP, Repsol Sinopec, Shell and Dana. Equinor and Ithaca, also listed, recently won approval to exploit the giant Rosebank oilfield off Shetland.

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