Apache Corp. (NYSE: APA) said Oct. 30 it has struck significant discoveries on two exploration wells in the Beryl area of the U.K. North Sea.

Additionally, Apache said it made a large discovery at its Seagull prospect, which lies about 50 miles south of the company's Forties Field. The oil field is the largest in the U.K. North Sea, the release said.

"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%," said Thomas E. Voytovich, Apache's executive vice president of international and offshore and E&P technology, in a statement.

Together, the Houston company estimates likely net recoverable reserves could be from 50 million barrels of oil equivalent (MMboe) to more than 70 MMboe.

Future appraisal drilling will enable the company to further define the upside potential beyond 70 MMboe. Apache's proved reserves in the North Sea at year-end 2014 were about 140 MMboe, according to the release.

The exploration wells in Beryl, named K and Corona, are the first exploratory prospects drilled by Apache in the area. Each discovery proves a separate geologic concept that helps to de-risk additional drilling locations, the release said.

"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," said John J. Christmann IV, Apache's CEO and president, in a statement.

The company also drilled two significant development wells, in the Beryl area, from which no reserves have been previously booked.

Details of the five discovery wells include:

  • K Discovery
    • After the initial discovery with the 9/19B-18 well in June 2015, Apache successfully drilled two sidetracks into adjacent fault blocks in the Beryl area. In total, this discovery includes more than 457 meteres (1,500 feet) of high-quality, oil-bearing sands within the Beryl, Linnhe, Nansen and Cormorant formations, across three distinct fault blocks. Apache is the operator of this discovery with a 55% working interest, and partner Shell has the remaining 45%.
  • Corona Discovery
    • The 9/18a-39A Corona exploration well, also located in the Beryl area, tested Apache's first Tertiary-aged injectite prospect. The well was drilled to a true total vertical depth subsea (TVDSS) of 1,954 meters (6,411 feet) and logged 69 meters (225 feet) total vertical depth (TVD) net pay in excellent reservoir-quality sandstone. Apache has a 100% working interest in this discovery.
  • Beryl ACN Development Well
    • Drilled from the Beryl Alpha platform, the ACN development well encountered 40 meters (131 feet) TVD net pay in the Nansen and 12 meters (40 feet) TVD net pay in the Eiriksson formations. The well was successfully completed in the Nansen and came online Oct. 8, at a test rate of 11,194 barrels per day (bbl/d) of oil and 30.4 million cubic feet per day (MMcf/d) of natural gas. Apache holds a 60.55% working interest in the well, and partner Shell has the remaining 39.45%.
  • Nevis Central L4S Development Well
    • The L4S pilot well, also located in the Beryl area, was drilled to a TVDSS of 2,834 meters (9,298 feet) and logged 114 feet TVD net pay in the Triassic Lewis formation. The pilot was followed by a high-angle producer that yielded a 30-day initial production (IP) rate of 45 MMcf/d of natural gas and 2,166 bbl/d of oil. The well has been producing since early July 2015. Apache has a 60.55% working interest in the well, and partner Shell has the remaining 39.45%.
  • Seagull Discovery
    • An appraisal well was drilled about 80 km (50 miles) south of the Forties complex in Block 22/29c in the Seagull Discovery and confirmed 672 feet of net oil pay over a 1,092-foot column in Triassic-age sands. The well was flow tested with a facility-constrained rate of 8,700 bbl/d of oil and 16 MMcf/d of natural gas with a very low pressure drawdown. Further appraisal work will continue following the recent acquisition of a multi-azimuth 3-D survey. Apache will assume operatorship of this license from Talisman Sinopec Energy UK Ltd. later this year subject to necessary approvals. Apache has a 35% working interest. Partners in the well include Talisman Sinopec Energy UK Ltd. with 50% working interest and JAPEX UK E&P Ltd. with 15% working interest.
Offshore