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AOGCC approves vertical gas pool expansion
Sterling-Beluga pool at Beluga River to include shallower interval; Hilcorp Alaska says 5 wells could have shallower completions Kristen Nelson Petroleum News
The Alaska Oil and Gas Conservation Commission has approved a request from Hilcorp Alaska for a vertical extension of the Sterling-Beluga gas pool at Beluga River to include a shallower interval.
In an Oct. 29 order the commission said the June 28 application from Hilcorp, the Beluga River operator, was for an amendment to Conservation Order No. 802 to vertically extend the pool allowing the company to perforate Sterling formation sands in the BRU 232-04 well in the expansion area. Hilcorp has identified four other wells which may be completed in the expansion area in the future.
The Sterling-Beluga gas pool, SBGP, contains some 8,227.1 acres, two-thirds onshore and the remainder offshore on the western side of Cook Inlet.
Hilcorp and Chugach Electric Association are the Beluga River unit working interest owners. From the surface down to 7,000 feet Hilcorp has one-third WIO and Chugach Electric has two-thirds WIO. Below 7,000 feet Chugach Electric holds a 100% WIO. The commission said the SBGP and proposed vertical expansion are Sterling and Beluga formation sands above 7,000 feet.
Landowners are the Alaska Department of Natural Resources, the U.S. Bureau of Land Management, Cook Inlet Region Inc., Chugach Electric and S&E Foster Properties.
History The commission said Standard Oil Company of California "unexpectedly discovered" the SBGP in a 1962 exploration well targeting oil in deeper horizons near the center of the present Beluga River unit. The well blew out April 28, 1962, at 3,249 feet measured depth "after drilling a portion of the upper Sterling Formation," a blowout Standard Oil attributed in a press release to "an unexpected high-pressure low-volume gas pocket." After drilling, completing and testing the well, Standard Oil said in another release that they had a "significant gas discovery." In late 1962 the well was completed and shut in. Four additional wells were drilled from 1962 to 1964, delineating the field.
Regular gas production began in 1968.
The commission said the SBGP averaged some 42.8 million cubic feet per day from 24 wells in August, with cumulative production from the field of 1.4 trillion cubic feet, with much of the production to date from the Sterling formation.
SBGP pool The SBGP previously encompassed the interval in well BRU 224-13 from 3,345 feet MD to 7,000 feet MD, equivalent to some 3,241 feet and 6,896 feet true vertical depth.
The Hilcorp request proposed to change the limits to 3,097 feet MD to 7,000 feet MD, equivalent to about 3,004 feet TVD and 6,896 feet TVD.
The commission said Sterling reservoir sands, up to 200 true vertical feet, are generally thicker and typically have excellent reservoir quality and little cementation. The underlying Beluga is generally much thinner, 3 feet to 50 feet TVD, "laterally discontinuous, isolated, lens-shaped bodies," and generally of lower reservoir quality with modest cementation.
The Hilcorp proposal adds 234 true vertical feet of shallower Sterling formation sands to the SBGP.
"There are over 100 individual sands within the proposed expanded pool with various drive mechanisms and gas and water contacts," the commission said.
Reservoir management "Hilcorp plans to actively work to extend the life of the field and increase the ultimate recovery," the commission said. "As is typical for gas field developments in the Cook Inlet Basin, Hilcorp plans to develop reservoirs from the bottom up in the wells, opening and isolating sands as necessary to achieve economically viable production. This may often involve having multiple sand bodies open at the same time in order to maintain adequate production rates."
In its conclusions the commission said expanding the SBGP to include shallower Sterling sands is appropriate for continued development of the gas pool.
--KRISTEN NELSON
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