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BP applies to expand Prudhoe Bay unit
Kristen Nelson Petroleum News Editor-in-Chief
Prudhoe Bay unit operator BP Exploration (Alaska) has applied to the Alaska Division of Oil and Gas to expand the Prudhoe Bay unit by some 1,040 acres as part of an expansion of the Aurora participating area, which would grow by approximately 3,040 acres. The division said the proposed expansion would increase the Prudhoe Bay unit to approximately 248,997 acres.
Aurora is one of the western Prudhoe Bay satellite fields. Expansion of the unit would be to the north. The Aurora participating area would be expanded both to the north and the south; the majority of that expansion area is already part of the Prudhoe Bay unit.
BP told the division that “subsurface well data and reprocessed seismic indicates that the recoverable hydrocarbon accumulation at Aurora field extends beyond the boundaries of the existing participating area.”
The proposed Prudhoe Bay expansion includes portions of sections 15, 16 and 17 of township 12 north, range 12 east, Umiat Meridian. The Aurora participating area expansion includes portions of sections 2, 3 and 4 of T11N-R12E, UM, and sections 15-17, 22, 23, 25 and 36 of T12N-R12E, UM.
BP has already received approval from the Alaska Oil and Gas Conservation Commission to expand the area covered by the commission’s pool rules for operation at Aurora. The commission said in June that BP cited subsurface wireline log data, pressure measurements and newly reprocessed seismic data in demonstrating that Aurora extended beyond the originally defined pool area. Wells required As a condition of the expansion the division is proposing to give BP until Oct. 15 to drill and provide results of the S-119 well into the northern expansion of the unit, or the expansion area acreage will be automatically eliminated from the unit. That well needs to be completed and put on production as either a producer or injection well by Nov. 15, or the northern expansion area will be eliminated from the unit and from the participating area.
BP then has until June 30, 2005, to drill and complete the S-111.
BP said in its fifth plan of development for Aurora, covering November 2004 through October 2005, that development of the reservoir has focused on phased drilling of an estimated 20 to 25 production and injection wells from S-Pad in the southeast area of Aurora.
Drilling at Aurora began in July 2000 and production began in November of that year. BP began water injection in December 2001 and enhanced oil recovery with miscible gas for water-alternating-gas injection in December 2003. By this summer, the company had completed 19 wells at Aurora, all from S-Pad: 11 oil producers; six water injectors; and two water-alternating-gas injectors.
BP said that response to the first six months of EOR was an aggregate of more than 1,000 barrels per day of oil.
In addition to the S-119 well, and the S-111 if the unit expansion is approved and results from the S-119 are favorable, BP said it also plans to drill an injection well and convert two pre-produced injectors to injection during this plan year.
The company has also begun preliminary engineering for water injection booster pumps at Aurora to ensure adequate injection pressure and rate with start-up expected in the second quarter of 2005.
The original oil in place at Aurora is estimated at 165-201 million barrels, formation gas at 112-137 billion cubic feet and the gas cap at 15-75 bcf. Cumulative oil production as of the end of June was 10.1 million barrels of oil, with a 10,545 bpd production rate.
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