State approves Torok PA at Oooguruk

Third participating area in North Slope unit thought to have 690 million barrels of oil in place, 170 billion cubic feet of gas

By Eric Lidji

For Petroleum News

The Alaska Department of Natural Resources approved the Torok participating area at the Oooguruk unit on June 24, the third at the near shore North Slope unit.

The Torok participating area covers 1,560 acres over parts of two leases — ADL 355036 and ADL 355037 — and extends from a measured depth of 4,991 feet to 5,272 feet.

Unit operator Pioneer Natural Resources Alaska Inc. owns a 70 percent interest in the unit and participating area and Eni Petroleum US LLC owns the remaining 30 percent.

Pioneer estimates that the Torok participating area contains 690 million barrels of original oil in place and believes it can recover up to 25 percent using primary and enhanced recovery techniques. Because the reservoir is highly laminated, Pioneer plans to drill horizontally and hydraulically fracture all wells, both producers and injectors.

While Pioneer hasn’t encountered any free natural gas at Torok to date, and doesn’t expect to in the future, the company estimates that the solution gas-to-oil ratio at the participating area is 250 cubic feet per barrel, yielding around 170 billion cubic feet of solution gas. (Solution gas is gaseous reservoir hydrocarbons dissolved in liquid reservoir hydrocarbons, mainly oil, because of the prevailing pressures in the reservoir. It’s also known as dissolved gas. Free gas is generally found in a gas cap — a hydrocarbon that exists in the gaseous phase at reservoir pressure and temperature and remains a gas when produced under normal conditions. It’s gas that is not dissolved into the oil.)

Unlike the Nuiqsut and Kuparuk participating areas, the Torok participating area will not have royalty relief and Pioneer will pay the State of Alaska a 12.5 percent royalty rate.

Because the Torok reservoir is relatively shallow, many early North Slope exploration efforts targeting the deeper Sadlerochit and Kuparuk formations encountered the Torok.

The wells with the most information about the Torok reservoir include Sinclair’s Colville No. 1 in 1965 and 1966, Texaco’s Colville Delta No. 2 and Colville Delta No. 3 in 1986, ARCO’s Kalubik No. 1 in 1992 (the discovery well for the Oooguruk-Nuiqsut Oil Pool) and Kalubik No. 2 in 1998, and Pioneer’s Oooguruk No. 1 and Ivik No. 1 in 2003.

In developing the deeper Nuiqsut and Kuparuk pools, Pioneer has drilled 18 wells penetrating the Torok interval, including the ODSN-45 (originally drilled to the Nuiqsut, but plugged back) and the ODSN-45A that produced 430 bpd from the Torok reservoir.

The Torok participating area went into effect retroactively to March 1, 2010, the approximate date that the ODSN-45A well began producing from the Torok reservoir.

Currently, Pioneer operates one production well and one injection well in the Torok participating area, but plans to drill two additional development wells this coming winter.

The Alaska Oil and Gas Conservation Commission approved pool rules for the Oooguruk Torok reservoir in late May, mapping the reservoir as lying offshore in the Beaufort Sea and onshore in the Colville River Delta, both inside and outside the existing Oooguruk unit. Pioneer recently applied to expand the unit to include the entire reservoir.

Pioneer plans to initially develop the Torok from the offshore drill site at Oooguruk, but might eventually add a new drill site on the eastern side of the Colville River Delta. The company refers to this as the Nuna development.