The UK's league table of top North Sea oil and gas producers has been reshuffled again after a year of significant mergers and acquisitions, with the prospective sale of BP's UK business expected to trigger further change, according to industry consultants.
Harbour Energy, which had held the top spot for several years, has been overtaken by Neo Next +, a newly formed operator created through the combination of Repsol's UK assets, Neo Energy, French supermajor TotalEnergies' UK business and, most recently, Deltic.
The updated rankings, compiled by Dundas Consultants using 2025 production figures, place Harbour Energy in second position, flanked by two new entrants formed from mergers of previously established players.
Adura, the independent joint venture between Shell and Equinor, took third place. The company had initially claimed it would become the largest operator in the North Sea when it launched, but the subsequent formation of Neo Next + altered the competitive landscape.
Ithaca Energy, which had climbed the rankings earlier through a combination with Eni and the acquisition of JAPEX's North Sea division, slipped from third to fourth place in the latest figures.
BP was recorded as the fifth largest producer in UK waters, according to the data. Dundas Consultants director Richard Woodhouse said the sale of BP's North Sea business to a rival operator could significantly alter the top of the table.
"We can see by adding the BP total that such a major transaction adds a little under 35 million boe per annum (or about 96 kboe/d) based on 2025 data, so would have the potential to really shake up the top of the table," Woodhouse told Energy Voice.
Ithaca Energy has previously been reported to have considered a takeover of BP's Clair hub West of Shetland, although that deal did not proceed. Given its history of seeking acquisitions involving BP assets, the company is regarded as a likely candidate to acquire the supermajor's North Sea business.
Adura retains the potential to reclaim the top position in future rankings, contingent on government approval for two major projects, Jackdaw and Rosebank. Consultation periods for both fields closed last week, leaving the decision on whether they proceed with the UK government, led by Prime Minister Andy Burnham.
"Given that we are already in August without clarity on the regulatory response, we might expect the impact on 2026 data to be modest," Woodhouse said. "However, if these important fields get the green light from the new Labour government, and 2027 sees a full year of production from both in line with the production forecasts published in their environmental statements, then Adura could be propelled to the top of the table on that basis."
Adura chief executive Neil McCulloch thanked those who took part in the recent consultation processes, describing Rosebank and Jackdaw as "nationally significant projects". He added: "Together, they can provide more domestically produced energy, support high-quality jobs and apprenticeships, generate substantial economic activity and tax revenues, and give the UK's world-class energy supply chain confidence for the future."
Adura is aiming to bring Jackdaw online by the end of this year and has spudded two wells tied to its Shearwater hub in 2025. It remains unclear what impact bringing new wells online later in the year would have on the company's position in the rankings.
Other operators are also working to bring new production online. Serica has repeatedly told shareholders it is close to securing a rig for North Sea activity, though its development plans are understood to be at an earlier stage than Adura's.
"I think it is too soon to speculate on the longer-term impact of the Adura and Serica drilling that is either underway or in the pre-Final Investment Decision planning stages," Woodhouse said. "Those wells across the two firms are varied in nature and include exploration, appraisal and development wells. For 2026, we can expect modest impact though."
Serica is expected to see a boost to its production figures once it completes its acquisition of Spirit Energy's UK assets. According to 2025 figures, the deal would add around 4.6 million barrels of oil equivalent to Serica's output, though the gains are not expected to be substantial in the wider context of the rankings.
"With Spirit's East Irish Sea production from 2025 being around half of their total, their southern North Sea assets add about 4.6 million boe to Serica for 2025," Woodhouse said. "With the exception of Cygnus, these SNS fields are generally very mature."
