State officials have approved a new oil pool at the Kuparuk River unit.
The Alaska Oil and Gas Conservation Commission approved a request from ConocoPhillips Alaska Inc. to establish the Kuparuk River-Torok Oil Pool at the unit.
The ruling allows ConocoPhillips to proceed with an oil development program from the existing Drill Site 3S at the North Slope unit and could led to additional pads in the future. The Kuparuk River-Torok Oil Pool is defined as “the accumulation of oil and gas common to and correlating with the interval within the Kalubik No. 1 well between the measured depths of 4,991 and 5,272 feet on the resistivity log recorded in exploratory well Kalubik No. 1,” according to the July 22 decision (Conservation Order No. 725).
ConocoPhillips applied for the pool in late March 2016, after several years of exploration and appraisal activity in the northwest corner of the Kuparuk River unit. The AOGCC held a meeting in early May, where company representatives provided testimony. The company originally referred to the accumulation as the “Moraine” interval, but the AOGCC decided to name the pool after the “Torok” formation present in the region.
The area included in the pool covers 22 leases, including two currently outside of the unit boundaries- ADL 392374 and ADL 392371. ConocoPhillips intends to apply for an expansion of the unit boundaries to incorporate those two leases, according to the ruling.
Development in phases
ConocoPhillips plans to develop the Torok pool in “discrete phases,” according to the Conservation Order, starting with a program to drill between 10 and 40 horizontal production and injection wells extending northwest from the existing Drill Site 3S. In an associated Area Injection Order, the AOGCC outlined a slightly smaller program of four to five hydraulically fractured horizontal producers and three to four fracture stimulated horizontal injectors, each with 3,000-foot to 8,000-foot horizontal sections through the formation. Future phases could be drilled from DS-3S, but ConocoPhillips also might build between one and two additional drill sites in the area, according to the rulings.
A development program from DS-3S could access between 100 million and 500 million barrels of oil in place, according to estimates included in the Area Injection Order. A primary recovery is expected to be approximately 5 percent, with certain enhanced recovery programs increasing that recovery rate to a range of 13 to 55 percent. A separate development at a hypothetical second drill site could access between 100 million and 500 million barrels of oil in place, according to the Area Injection Order, with similar recovery rates.
Reconsidering the region
Exploration in the region goes back decades.
Sinclair Oil and Gas penetrated the reservoir in 1966 with the Colville No. 1 well, and Texaco Inc. returned in 1985 and 1986 to drill the Colville No. 2 and Colville No. 3 wells much farther to the north. The Texaco wells produced less than 50 barrels of oil per day, although production from the Colville No. 3 well increased after fracture stimulation. ARCO Alaska Inc. drilled the Kalubik No. 1 well in 1992 and the Kalubik No. 2 well in 1998 and a test of the former well produced only 10 barrels of oil per day on average.
Recent interest in the Torok formation started with work at the Oooguruk unit to the northwest. All the wells at the offshore unit passed through the Torok en route to deeper formations. Between 2010 and 2012, former operator Pioneer Natural Resources Alaska Inc. drilled and completed three wells within the Torok turbidite sands and delineated the formation with the Nuna No. 1 well, which produced 1,524 barrels per day. In May 2011, the AOGCC formed the Oooguruk-Torok Oil Pool to guide development of the pool.
In 2013, ConocoPhillips returned to the existing KRU 3S-19 well, which it had drilled about a decade earlier, to fracture stimulate the upper portion of the Torok turbidite sequence. The well produced between 250 and 300 barrels per day during a flow test.
The results convinced the company, in 2015, to drill the KRU 3S-620 well horizontally through a 4,200-foot section of those turbidite sands. The well produced 1,575 bpd, with a water cut of 75 percent. Also in 2015, ConocoPhillips drilled the vertical Moraine 1 well from an ice pad “to acquire extensive logs with whole core for detailed reservoir and overburden characterization studies, including special core analysis.”
Earlier this year, ConocoPhillips returned to the area to drill the corresponding 3S-613 injection well nearby. “Results from special core analyses and reservoir performance from the 3S-620 producer well and 3S-613 injector well will guide future development plans for the Moraine interval,” the company wrote in a recent plan of development.
Since returning to the 3S-19 well in 2013, ConocoPhillips has been reporting oil production from the formation through the Kuparuk River Torok Undefined Oil Pool.
Turbidite sands have given other operators difficulty. Given their nature, all wells into the new pool will likely be fracture stimulated “to enhance productivity, improve vertical injection sweep, and connect thin, individual sandstone beds,” according to the AOGCC. The approval includes no spacing restriction for wells, aside from a general prohibition against opening pay to a well within 500 feet of a property line with a different owner.
Along with the new pool rules, the AOGGC issued an area injection order (Area Injection Order No. 39) allowing ConocoPhillips to conduct injection for enhanced recovery.
