(WO) – The North Sea Transition Authority (NSTA) estimates UK proven and probable (2P) oil and gas reserves at 2.5 billion barrels of oil equivalent (Bboe) as at the end of 2025, 0.4 Bboe lower than a year earlier.
The fall reflects production of around 380 MMboe in 2025 that was not offset by additions. No new field development plans (FDPs) were consented during the year and one FDP addendum was approved. Producing fields added a net 40 MMboe from in-field activity, improved performance and cessation-of-production deferrals, partly offset by downward revisions and earlier cessation at some fields, giving an underlying reserves replacement ratio of +10%.
No exploration wells were drilled on the UK Continental Shelf in 2025.
The central estimate of contingent resources rose by 0.3 Bboe to 6.5 Bboe, as operators progressed nine new proposed developments and revised estimates for existing fields, while some sanctioned projects were downgraded. Within that total, producing fields account for 1.5 Bboe, proposed new developments 1.6 Bboe, licensed marginal discoveries 1.3 Bboe and unlicensed marginal discoveries 2.1 Bboe.
Mean licensed prospective resources in mapped leads and prospects are estimated at 1.2 Bboe, down from 1.5 Bboe, with a further 3.6 Bboe unlicensed. A further mean 11.2 Bboe of unlicensed prospective resources is estimated to lie in plays outside mapped leads and prospects.
Reserves and discovered resources remain about 70% oil and 30% gas on an oil-equivalent basis. The UKCS had produced 48.1 Bboe by the end of 2025.
The regulator noted that reserves at developments affected by a Court of Session judgment that quashed their consents are still classified by operators as reserves; licensees may proceed with development works, but no oil or gas may be produced while the consent decision is pending. Reserves and resource figures for fields were compiled from operator data and have not been audited by the NSTA.
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