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Conoco offers Fiord pool rules Asks AOGCC to agree to single Fiord oil pool, applies for area injection order Alan Bailey Petroleum News Staff Writer
On Nov. 22 ConocoPhillips Alaska Inc. proposed pool rules to the Alaska Oil and Gas Commission for the Fiord satellite field at the company’s CD3 development in the Colville River Unit.
“ConocoPhillips Alaska Inc. (CPAI) as operator of the Colville River Unit, requests a conservation order by the commission regarding the classification of the Fiord reservoirs as an oil pool and prescription of rules to govern the proposed development and operation of the pool,” said Chris Alonzo, development supervisor, western North Slope, for ConocoPhillips Alaska, in a letter that accompanied the proposal. “CPAI also requests an area injection order authorizing enhanced recovery operations for the proposed Fiord Oil Pool.”
ConocoPhillips’ Alaska predecessor ARCO Alaska began drilling at Fiord in 1992 and in December of that year announced a discovery at the Fiord No. 1 well. ARCO and partner Anadarko Petroleum Corp. said in July 1999 that they estimated Fiord to contain more than 50 million barrels of proven and potential reserves.
Fiord is a roadless development in the Colville River delta — last winter ConocoPhillips mined gravel for pads and an aircraft landing strip. At that time the company also completed one well and started two other wells. Production, slated for startup in 2006, will go through the Alpine facilities. Two zones Fiord consists of two zones, one zone in the Nechelik sand of the Jurassic Kingak formation and the other zone in the Kuparuk C sand of the Cretaceous Kuparuk River formation. ConocoPhillips is requesting that the two zones be classified as a single Fiord oil pool, within what AOGCC terms the Colville River Field. The Colville River Field already contains two defined oil pools, Alpine and Nanuq.
Oil gravity from the two Fiord zones ranges from 29.4 to 31.3 degrees API.
A northwest trending fault known as the Fiord fault forms a trap on the eastern side of the Kuparuk zone, “with stratigraphic pinchouts elsewhere,” according to ConocoPhillips’ pool rules proposal — the structure generally dips to the north and the sand thins westward from the fault. The underlying Nechelik zone is truncated by the lower Cretaceous unconformity to the north of the development area and the sand quality degrades to the south and west, the proposal says.
Although a wedge of non-reservoir Kingak sandstone and shale separates the zones in the area of two of the Fiord wells that have been drilled, “Kuparuk sand and Nechelik sand are contiguous in the oil column” at the toe of horizontal well CD3-108, according to the proposal. And oil analysis indicates that the oil in both zones “are likely the same oil” and originated from the same source rock.
The fact that there is a connected oil column with sand-on-sand contact between the two reservoir zones provides the basis for ConocoPhillips’ request to establish a single oil pool.
However, the working interest owners also plan to apply to the state of Alaska and Arctic Slope Regional Corp. in early 2006, to form a separate participating area for each zone. 17 horizontal wells ConocoPhillips plans 17 horizontal wells at the Fiord CD3 development. Six producers and six injectors will form an array of parallel well trajectories within the Nechelik zone, with each well directionally drilled from the CD3 drill site. Three producers and two injectors will work the Kuparuk zone. In both zones injectors will alternate with producers.
Slotted liners are planned for wells in the Kuparuk zone but wells in the Nechelik zone will have open-hole completions.
The proposal to AOGCC requests that well spacing requirements under the commission’s regulations “should be waived because the horizontal well development will yield greater recovery than a conventional well development with a minimum spacing rule.” Planned inter-well spacing is 2,100 feet for the Nechelik and 4,500 feet for the Kuparuk, with the possibility of different well spacings after analysis of reservoir performance.
Each well will only enter a single zone — allocation of production and injection back to working interest owners by participating area will be achieved by multiplying total production from the satellite field by a calculated well allocation factor, based on well test data. Enhanced recovery ConocoPhillips proposes using a miscible water alternating gas technique for enhanced recovery from the Fiord oil pool. This technique involves sweeping the reservoir with miscible injectant after applying waterflood — the miscible injectant mobilizes oil not swept by the water. Alternating slugs of water and miscible injectant from the injection wells then progressively move oil towards the production wells.
The company anticipates annualized production rates of between 10,000 and 25,000 barrels per day for the Nechelik zone and between 4,400 and 15,700 bpd for the Kuparuk zone. Those production rates will require annualized injection rates in the Nechelik zone peaking at 18,000 barrels per day of water and 12 to 29 million standard cubic feet of miscible injectant gas. The corresponding injection figures for the Kuparuk zone are 5,300 to 18,900 barrels of water per day and 3.7 to 13 million standard cubic feet per day of gas.
Initial water injection will use seawater, but later in field life produced water will become available for injection. Miscible injectant will come from the central Alpine facility.
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