A drill rig works for Repsol at its Colville Delta operations this past winter. Repsol, which has been exploring for three years on the North Slope, released its first well flow data and said the results show “significant development potential.”
Repsol released encouraging results June 2 from testing two exploration wells drilled this spring on the Colville River delta on the North Slope.
It’s good news for the State of Alaska, which owns the lands, and for Arctic Slope Regional Corp. of Barrow, which shares in ownership of the mineral rights.
ASRC would receive a share of royalties from any oil and gas production.
One well, Qugruk 8, or Q-8, flowed 30 degree API gravity oil at rates of up to 2,160 barrels per day. A second well, Qugruk 301, or Q-301, flowed 4,600 barrels per day from a horizontal test well.
Repsol has a 70 percent stake in the leases with 22.5 percent owned by 70&48 LLC, a subsidiary of Armstrong Oil and Gas, and 7.5 percent owned by GMT Exploration Co.
Additional drilling is planned in the area next winter, Repsol said in the June 2 announcement.
“We are very satisfied with the latest results from Alaska,” said Luis Cabra, Repsol’s executive vice president for exploration and production. “The positive news from this year’s exploration campaign, combined with the recent changes in the state’s tax structure, make Alaska a compelling area to continue to invest and generate the potential for development.”
Significantly, the production test from the horizontal well segment experienced “minimum bottom hole pressure drawdown,” according to a statement by Armstrong Oil and Gas, a minority partner in the well.
Little change in the reservoir pressure during the test indicate that the reservoir has good potential.
The results were better than anticipated, Repsol said in a statement issued from Madrid, Spain, where the company is headquartered. The 30 degree API gravity is similar to the oil quality in the Kuparuk and Prudhoe Bay fields farther east.
“Added to the positive results from previous (drilling), this confirms the significant development potential of the area,” the company said.
In its statement, Armstrong Oil and Gas said wells penetrated a reservoir section that was 95 feet thick at a depth of 6,500 feet, with a porosity of 15 percent to 25 percent. Seismic data information from other wells shows the pool covers over 15,000 acres.
Armstrong called the reservoir “Alpine East,” indicating that it is similar, or perhaps a broken-off part, to the large nearby Alpine field operated by ConocoPhillips
A separate formation discovered, called Nanushuk, is estimated to cover 25,000 feet at a depth of 4,100 feet, with an “oil column” of 650 feet, meaning the depth of rock containing oil, with 150 feet of “net pay”, a section of that that is conducive to commercial production. Porosity was measured as 25 percent on average.
An API gravity measurement was not given for the shallower Nanushak oil, leading some independent analysts to believe the oil may be cool and thick, being near the permafrost layer that extends down from the surface.
That kind of formation has been encountered elsewhere, such as in the West Sak viscous oil in the Kuparuk field or the Torok formation near the Oooguruk field west of Kuparuk.
Earlier this spring Repsol said it would submit applications for development permits in June with state and federal agencies. The company has reported positive results with 16 exploration wells and “sidetracks,” or separate wells drilled off a vertical well from the surface, over four winter seasons, but has not previously released results of flow tests, however.
In its statement Armstrong said, “Additional drilling is needed to confirm the ultimate size of some discoveries, this season’s results justify moving forward with development, and two of the (newly discovered) fields are in the process of being permitted for development, one in the Nanushuk and the other in the Alpine.”
The area Repsol is exploring is north and east of the producing Alpine oil field owned by ConocoPhillips and Anadarko Petroleum. It had long been known that oil is present in small accumulations scattered across the Colville River delta area but it was not known if the deposits were big enough to develop commercially.
Repsol faces environmental and technical challenges in developing the discoveries, however. The oil finds are in ecologically-sensitive wetlands area, which will pose challenges in siting production facilities, pipelines and roads.
The company has not released details of its development plan but at least one stand-alone production facility is planned, according to sources familiar with Repsol’s planning