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Conoco applies to expand Kuparuk, Tarn Kuparuk River unit, two participating areas, Kuparuk and Tarn, would be expanded to include more of Kuparuk, Bermuda formations Kristen Nelson Petroleum News
ConocoPhillips Alaska has applied to the Alaska Department of Natural Resources’ Division of Oil and Gas to expand the Kuparuk River unit by some 2,880 acres, 320 acres in the Kuparuk participating area and the remainder in the Tarn participating area.
The working interest owners in the expansion area include ConocoPhillips, the Kuparuk operator, and BP Exploration (Alaska), Chevron U.S.A. and ExxonMobil Alaska Production.
ConocoPhillips told the state the proposed Kuparuk participating area expansion is due west of drill site 2A, northwest of drill site 2M and along the western edge of Kuparuk.
Expansion of this area is based on both the Kuparuk C and A sands being mapped into the production area, current acquisition of seismic data to improve imaging and mapping and reservoir engineering data which “demonstrates that oil is being drained from the tract and produced through the nearby development wells.”
ConocoPhillips said the Kuparuk participating area expansion is on the western flank of the Kuparuk anticline; the reservoir occurs at subsea depths of approximately 5,900 feet. The company said it believes injector wells 2M-05 and 2M-06 are sweeping oil from the expansion area to offset producers 2A-25 to the north and 2M-01 to the south.
The Kuparuk River unit working interest owners are acquiring new western Kuparuk 3-D seismic data over the expansion area to provide better information.
ConocoPhillips said the proposed modification of the Kuparuk participating area is based on adding areas included within a 2,700-foot drainage radius.
Tarn PA expansion Expansion of the Tarn participating area is based on adding areas within a 2,700-foot drainage radius from active wells and areas that demonstrate a minimum mapped net pay thickness of 1 foot.
ConocoPhillips said the criteria are based on surveillance results from development wells and mapping from integration of a refined Tarn log model and seismic acquired over Tarn in 2008. Five areas are included in the Tarn expansion application.
More than 100 million barrels of 33-37 degree API oil had been recovered from Tarn by the end of 2010 and 74 wells have been drilled in the current Tarn participating area, ConocoPhillips said.
Proposed expansion of the Tarn participating area is based on results from development drilling on the northern and eastern flanks of the 2L area Bermuda reservoir, as well as the northern, southern and eastern flanks of the 2N area Bermuda reservoir, the company said.
The Bermuda reservoir is the sequence of turbidite sandstones, siltstones and mudstones discovered in the 1991 ARCO Bermuda No. 1 well between 5,342 and 5,608 feet measured depth. ConocoPhillips said the Bermuda reservoir turbidite systems at Tarn are part of the late Cretaceous lower Seabee formation.
A high-quality 3-D seismic survey was acquired over the Tarn field in the winter of 2008. Analysis of the seismic, including 4-D effects, “led to the recognition of a fracture system aligned with wells experiencing premature injection breakthrough,” the company said, and recognition of this preferential flow pattern improved understanding of sweep orientation.
“New development drilling opportunities are now planned to take advantage of this sweep orientation,” ConocoPhillips said, adding that the new seismic data also “dramatically improved” understanding of the extent of the Tarn field.
Tarn is an enhanced oil recovery project using miscible water alternating gas injection.
Prior exploration ConocoPhillips said there have been no recent exploration activities in the Kuparuk participating area expansion.
Prior exploration in the Tarn participating area included the 1991 ARCO Bermuda 1 well and the 1992 ARCO Tarn 1 well. The first 3-D seismic was acquired over the Tarn expansion area in 1996 and interpretation of that seismic led to drilling of the Tarn 2, Tarn 3, Tarn 3A and Tarn 4 wells in the 1996-97 winter drilling season.
The 2N-310 well appraised and tested the younger Cairn interval at Tarn in 2008; Cairn tested gas. The same well tested the deeper Esker interval which was found to be uneconomic. Esker was also tested in the 2N-327 well, which found the interval to be wet.
Exploration, development plans ConocoPhillips said it is currently acquiring western Kuparuk 3-D seismic: That data will be acquired and evaluated in 2011-12. The company said there are no current plans to drill on the Kuparuk participating area expansion.
No exploration is planned for the Tran expansion areas.
“Acreage within the expansion areas is accessible from existing Tarn surface facilities,” and ConocoPhillips said new drilling and completion methods, including horizontal wells with multistage fracture stimulations and coil-tubing drilling, are being evaluating for Tarn.
Areas for possible future drilling include thinner distal lobes that were previously considered uneconomic, and the company said it expects that future wells will be spread out over several years to evaluate new technology for incorporation into later wells.
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