Apache said it has made significant discoveries in the North Sea in both the Beryl and Forties field which could up to 70million barrels of oil equivalent.
The US explorer said two discoveries were made on two exploration wells in the Beryl area as well as further discovery 50 miles south of the company’s Forties field.
Apache said it also drilled two development wells in the Beryl area from which no reserves have previously been booked.
The K and Corona wells are the first exploratory prospects drilled by Apache in the Beryl area.
Apache said both prospects as well as the success at the Seagull prospect not far from the Forties field could hold recoverable reserves of between 50 and 70 million barrels of oil equivalent.
Further appraisal drilling will take place to help define the upside potential, the company said.
In total, five discovery wells have been uncovered.
Thomas Voytovich, Apache’s executive vice president – International and Offshore and E&P Technology, said: “Apache’s exploration program in the high-potential Beryl area is off to an exceptional start.
“The success of our first two exploration wells at Beryl, combined with the Seagull discovery, could increase our total North Sea proved reserve base by more than 50 percent.
“Importantly, results obtained from the wells announced today emphasize the quality of our seismic surveys and the accuracy of our geologic model in the Beryl area.
“Our large discovery at Seagull will likely have a longer investment time-horizon as it may require dedicated production facilities, but it is expected to have a very meaningful impact on
Apache’s medium- and long-term production in the region.
“We look forward to discussing the economics and details of these discoveries, along with a review of our extensive North Sea prospect inventory during our North Sea Region webcast Nov. 17.”
The Oil and Gas Authority said it “welcomed” the news of the new discovery.
The Seagull discovery was drilled about 50 miles south of the Forties complex in Block 22/29c and confirmed 672 feet of net oil pay over a 1,092 foot column in the Triassic-age sands.
The well was flow tested with a facility-constrained rate of 8,700barrels per day and 16MMcfd with a very low pressure drawdown.
Apache said further appraisal work will continue following the recent acquisition of a multi-azimuth 3D survey.
The company said it will assume operatorship of this license from Talisman Sinopec Energy UK later this year subject to approvals.
Apache has a 35% working interest while Talisman currently has a 50% working interest and Japex UK a 15% share.
The K discovery was made after Apache drilled two sidetracks into adjacent fault blocks in the Beryl area.
In total, the company said, the discovery includes more than 1,500 feet of high quality, oil bearing sands with the Beryl, Linnhe, Nansen and Cormorant formations across three distinct fault blocks.
Apache is the operator of the discovery with a 55 % working interest and partner Shell has the remaining 45%.
John J Christmann, IV, Apache’s chief executive officer, said: “The North Sea team has generated tremendous value in 2015 for Apache shareholders, despite a significant year-over-year reduction in capital spending.
“The discoveries we announced today, coupled with the North Sea’s substantial inventory of development locations, provide low-risk investment optionality at very attractive rates of return.
“Our objective is to achieve a balanced investment profile of short-, medium- and long-cycle projects across our global portfolio.
“The North Sea discoveries we announced today are attractive across the full spectrum of those investment time horizons.
“These discoveries further reinforce our confidence that our North Sea business has the ability to sustain production volumes, extend the Forties and Beryl productive lives out beyond 2030 and consistently provide significant free cash flow back to the corporation.”
Meanwhile the Corona discovery was also made in the Beryl area which Apache has a 100% working interest in.
The Beryl ACN development well was drilled from the Beryl Alpha platform and encoutered a net pay in the Eiriksson formations.
The well was successfully completed in the Nansen and came online earlier this month with a test rate of 11,194 barrels of oil per day and 30.4million cubic feet of natural gas per day.
Apache holds a 60.55% working interest in the well and partner Shell has the remaininf 39.45%.
The fifth and final discovery was the Nevis Central L4S development well also located in the Beryl area and has been producing since July.
Apache has a 60.55% working interest in the well and Shell has the remaining share of the stake.
Houston-based Apache, which this year celebrates the 40th anniversary of production from its North Sea Forties field, invested more than £500million in the UK business last year despite the oil price slump.