The Bressay and Bentley sites - so close to Kraken that they can be connected using the same production system - are thought to have anywhere between 600 million and one billion barrels of oil in reserve.
Around 200-300 million barrels are expected to be extracted from the former, "one of the largest undeveloped oil fields in the UK continental shelf", according to EnQuest.
It's believed that Bentley could be even larger, capable of producing upwards of 300 million barrels.
Craig Baxter, of EnQuest, said the gas initially extracted from the Bressay field will be used to power operations on Kraken, replacing diesel fuels and therefore cutting emissions.
He added: "EnQuest continues to explore ways to progress the respective development of the Bressay and Bentley fields.
"EnQuest is committed to supporting the energy transition in the UK and any future field development will be conducted in line with EnQuest’s commitment to reaching net zero scope 1 and 2 emissions by 2040.
"This would significantly reduce Kraken’s emissions, by displacing diesel that is currently being used to power field operations."
Bressay and Bentley, around 80 miles east of Shetland, have the potential to produce more barrels of oil than the Rosebank and Cambo fields combined.
Rosebank, which is expected to produce around 350 million barrels, was finally given the green light in September last year, 19 years after being discovered.
Cambo, capable of producing around 170 million barrels, was originally discovered in 2002 but has been in limbo since 2021 when Shell pulled out of the project.
The drilling could reignite the North Sea political battle ahead of the General Election with Labour, whom pollsters expect to win, threatening to ban new exploration licences, as well as making detrimental changes to the Energy Profits Levy (EPL) which an investment bank has warned could cost up to 100,000 jobs.
Sir Keir Starmer's plans, announced nearly two months ago, would see the windfall tax on oil and gas profits be increased to a total of 78%, while investment allowances would be removed from the policy.
Scottish Labour leader Anas Sarwar told ChamberTalk last month that they have a "suite of packages" designed at lowering household bills, but there are fears that the UK's energy supplies would be further risked before a having a suitable replacement to oil and gas.
Labour's Green Prosperity Plan led to industry-wide warnings of job losses at a huge scale, as well as up to £20bn in lost revenues.
But the Conservative Party, who themselves went against industry warnings and extended the tax in its current form until 2029, insists they're "backing the UK's oil and gas industry" and "supporting around 200,000 jobs".
Since the Tories introduced the policy, more than 1,000 jobs have been lost as a direct result of the EPL.
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