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Oooguruk-Torok pool rules approved
Kristen Nelson Petroleum News
The Alaska Oil and Gas Conservation Commission has approved pool rules for the Oooguruk-Torok oil pool in the Oooguruk field on Alaska’s North Slope.
The commission said in a May 26 order that as currently mapped the Torok lies offshore in the Beaufort Sea and onshore in the Colville River Delta, both inside and outside the existing Oooguruk unit.
Operator Pioneer Natural Resources Alaska has applied to the Alaska Department of Natural Resources for expansion of the Oooguruk unit.
The Torok oil pool at Oooguruk will initially be developed from the offshore Oooguruk drill site; additional development may occur from a new drill site on the eastern side of the Colville River Delta.
Oooguruk operator Pioneer Natural Resources Alaska has a 70 percent working interest in the planned development area; Eni Petroleum US LLC holds the remaining 30 percent.
The Torok sandstone was first penetrated in 1965 by the Sinclair Oil and Gas Colville No. 1 exploration well, south of the southern border of the proposed development area. Texaco Inc. drilled and tested the Colville Delta No. 2 and 3 exploratory wells in 1985 and 1986, but flow rates from the Torok were less than 3 barrels per hour. Fracture stimulation of the lower portion of the Torok in Colville Delta No. 3 resulted in an average flow of 240 bpd during two tests totaling 84 hours.
Regular production in 2010 In March 2010 Pioneer fracture stimulated the 3,800-foot horizontal Torok interval in the ODST-45A well, drilled from the offshore Oooguruk drill site, and began regular production. As of March 1, the ODST-45A had produced 167,681 barrels of oil over 328 days, the commission said, an average of 511 bpd.
Eighteen wells have penetrated the Oooguruk-Torok reservoir to date and the commission said that information from those wells, nearby exploration wells and two overlapping 3-D seismic surveys was used to determine the geologic structure and reservoir distribution for the Oooguruk-Torok.
The commission said a three-well pilot program, ODST-45A and two other horizontal wells, will further define the reservoir.
Torok gravity measures 24 degrees API, reservoir temperature is about 135 degrees Fahrenheit and initial reservoir pressure is 2,250 psi at minus 5,000 feet subsea. The commission said free gas has not been encountered in the Torok interval.
Original oil in place is estimated to be 340 million barrels in the Oooguruk offshore drill site area and the core area — the planned initial development area where the Oooguruk-Torok reservoir is completely filled with oil. In the prospective area, the planned future expansion area where the Oooguruk-Torok reservoir appears to be only partially filled with oil, the original oil in place is estimated at 690 million barrels.
Primary recovery would be 5 percent of the OOIP; primary plus waterflood recovery is expected to recover 20 percent of OOIP, 68 million barrels in the ODS and core area, and 138 million barrels in the prospective area.
The commission said the production rate for the Oooguruk-Torok oil pool over an expected 20-30 year project life is expected to average 4,000 to 9,000 bpd, with peak production of about 8,000 to 15,000 bpd and 2 million to 8 million cubic feet of gas per day early in the project life.
Development in phases The commission said Pioneer plans to develop the Oooguruk-Torok in phases with about 25 horizontal production and injection wells. The horizontal sections of the wells will be some 5,000 to 8,000 feet in length within the reservoir and be spaced about 1,500 feet apart.
The reservoir will be developed as a water- and water-alternating-gas-injection enhanced oil recovery project.
Production wells will be equipped with electric submersible pumps.
Production will be allocated by use of a multiphase flow meter instead of a separator, with the Oooguruk allocation system calculating a theoretical volume for all well streams each day and the theoretical volume for each well summed to calculate total theoretical volume for all Oooguruk wells.
The commission said the proposed production and fiscal allocation system is consistent with the methodology employed for the Oooguruk-Kuparuk and Oooguruk-Nuiqsut oil pools.
Because the Oooguruk-Torok is compartmentalized, the commission is authorizing unrestricted well spacing to optimize waterflood efficiency and resource recovery, subject to a 500-foot set-back requirement from external property lines where owners and landowners are not the same on both sides of the line, thus protecting correlative rights of owners and landowners of offset acreage.
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