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Colville production expands westward into NPR-A
Production from Alaska’s North Slope continues to move west, with ConocoPhillips Alaska applying to expand the Colville River unit on the western edge of existing production to the west and southwest, including acreage in the National Petroleum Reserve-Alaska.
The company filed a unit expansion request with the U.S. Bureau of Land Management, Arctic Slope Regional Corp. and the State of Alaska to include an additional 16,400 acres in the unit, an area to be developed by the company’s proposed Alpine West or Colville Delta 5 drilling pad.
Conoco began permitting work on CD-5 in 2005 but withdrew the permits, restarting the project late last year when it reached agreement on the location of a bridge across the Colville River.
This Colville River unit expansion includes acreage in NPR-A, with some 8,200 acres of the expansion on federal lands, some 7,600 acres on ASRC lands and some 600 acres jointly held by the state and ASRC.
The expansion is out for public review until Aug. 24.
In a July 8 application letter ConocoPhillips said it expects to evaluate the expansion area, where it has already acquired 3-D seismic and drilled exploration wells, in 2010 through 2015.
Exploration began in 1998 Conoco said in its application that the western expansion of the Colville River unit is needed to continue the western extension of the Alpine and Nanuq-Kuparuk fields. The company said four wells and 3-D seismic help define the limits and reservoir potential of the expansion area.
The wells include Nuiqsut 1, CD2-33, CD4-321 and CD4-322, drilled between 1999 and 2007.
Conoco said the Nuiqsut 1 was drilled as part of the western delineation program for the Alpine field. Data from the well helped establish Alpine-A reservoir quality and to demonstrate the oil charge west of the Alpine field, the company said. The well was plugged and abandoned.
The CD2-33 well, drilled in 2001 from the CD2 pad at Alpine, helped determine the western edge of the Alpine field C sand; the well showed the Alpine-A reservoir continued south of the Nuiqsut 1 well. CD2-33 was abandoned and later completed as a horizontal well, CD2-33B, in the Alpine field.
CD4-321 was drilled in 2006 as part of the CD4 development program and is a Kuparuk sandstone injector, Conoco said. It was drilled to a depth sufficient to evaluate the Alpine C and A intervals. CD4-321 is the southernmost Alpine-A sandstone penetration, Conoco said. It lies south of the proposed CD-5 development and helps establish the lowest-known oil for the Alpine-A sand and the southwestern control for reservoir quality.
CD4-322 was drilled in 2007 as part of the CD4 development program and is also a Kuparuk sandstone injector 5,500 feet north of CD4-321. It was drilled through the Alpine C and A intervals and showed reservoir quality sands in the A interval. The well is near the southern limit of the proposed CD-5 development.
Conoco said all of the wells contain oil-charged Alpine-A sandstone and seismic data indicate continuation of the Alpine-A sandstone westward from the wells. None of these wells were tested, the company said, but western development wells are producing some 2,000 barrels per day of oil and are approaching the western boundary of the current Colville River unit.
The company also said western expansion of the unit is necessary for the western continuation of the Kuparuk sandstone from the CD4-Nanuq pad. The two western-most wells from CD4, Kuparuk injector wells, both contain Kuparuk sandstone and that sandstone is comparable in thickness to sandstone at the center of the CD4 Kuparuk field.
Wells recently completed or planned from the Alpine CD2 drill pad will complete that drilling program and are “near the western limit of the current unit and at the western drilling limit.” A well scheduled for mid to late 2009 straddles the participating area for the Alpine A sands and will be adjacent to the Nuiqsut 1 well.
Both the Alpine A and Kuparuk sandstones would be developed with horizontal wells from the new western drilling pad being permitted as the Alpine West-CD5 pad.
Under the schedule for this pad, drilling would begin in 2012-13, with an estimated 13 Alpine and two Kuparuk wells planned.
“In the event of success a total of 22 Alpine A sandstone wells and two to four Kuparuk wells would be needed to develop the fields,” Conoco said. The company said reservoir quality would be the main factor in determining the extent of the drilling program, “however, well data already show that both sand bodies extend west well beyond the current unit boundary.”
Depending on results of the core drilling program and reservoir quality, additional upside wells may be drilled, the company said.
Ice roads in 2010 The project schedule — following a restart of the CD-5 project late last year — shows permitting completed at the end of 2009; ice road construction in the fourth quarter of 2010; and gravel placement and bridge piers in 2011, the first year of construction.
Following ice road construction in the fourth quarter of 2011, the second year of construction includes bridge structure, pipelines and power and facility construction beginning in 2012, with drilling beginning that year. Facilities construction and drilling would be completed in 2013, with CD-5 production startup in the fourth quarter of 2012.
—Kristen Nelson
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