AOGCC approves EOR for Nanuq oil pool

Waterflood to start by end of year, miscible gas injection in 2007; recovery with EOR estimated at 24-66 million barrels

Petroleum News

The Alaska Oil and Gas Conservation Commission has approved injection for enhanced oil recovery at the ConocoPhillips Alaska-operated Nanuq oil pool in the Colville River unit on Alaska’s North Slope.

Nanuq (CD4) a satellite field south of the Alpine field, and Fiord (CD3), a satellite north of Alpine, are currently under development; oil from both will be processed through existing facilities at Alpine, the primary field in the Colville unit.

The Commission said enhanced recovery injection at Nanuq is proposed within the Nanuq oil pool in a zone correlative to the Nanuk No. 2 exploration well between 7,043 feet and 7,223 feet measured depth.

Nanuq will be developed with 16 horizontal wells, nine producers and seven injectors.

Water alternating with miscible gas injection will be implemented with water injection scheduled to begin in late 2006 followed by miscible gas injection beginning in 2007.

Peak production rates are expected to be between 4,000 and 11,000 barrels per day, with waterflood injection rates expected to peak at between 3,500 and 9,600 bpd and miscible gas injection rates estimated to peak at 12 million to 33 million standard cubic feet per day.

Original oil in place 84-169 million barrels

Nanuq is a Cretaceous-aged basin floor submarine fan system dominated by lobe-sheet deposits. The reservoir consists of fine-grained sandstone with interbedded shale layers. The commission said the best reservoir-quality rock is generally in the upper part of the interval.

The oil-water contact is at 6,207 feet true vertical depth and a gas cap is believed to be present with gas-oil contact at about 6,100 feet tvd.

Fluids requested for injection include: water from the Beaufort Sea; miscible gas from the Alpine central facility; produced water from the Nanuq oil pool; produced water from the Alpine oil pool and other Alpine satellite pools; and fluids collected from sumps, hydrotests, rinsate from washing mud hauling trucks, excess well-work fluids and treated camp waste water.

Seawater is planned as the initial waterflood source and the commission said it has been tested in core flood studies and found to be compatible with the injection zone. Other sources of water will be used later in field life and the commission said ConocoPhillips reports there is no evidence that other sources of floodwater will be incompatible.

The injection rates will be adjusted to manage voidage from the reservoir and injection of water and miscible injectant will alternate in each injection well.