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Eni looks north from Nikaitchuq
Eni Oil and Gas is discussing plans for extended-reach exploration wells to be drilled into federal Outer Continental Shelf leases the company holds north of its producing Nikaitchuq field, which is in state-owned nearshore waters on the North Slope.
Eni would not comment on the plan but Alaska’s U.S. Bureau of Safety and Environmental Enforcement director, Mark Fesmire, confirmed discussions are underway.
Fesmire made the remarks at a Society of Petroleum Engineers meeting in late May. The wells would be some of the longest extended-reach wells drilled to date, Fesmire said.
In a written statement, Eni’s safety, environment and quality manager Whitney Grande said, “Given the success of our existing Nikaitchuq development, Eni continues to review near field opportunities, including those reaching into Federal OCS lands.”
Leases expire in 2017 Eni is owner or part-owner of 29 OCS leases in the area which will expire between July and December 2017, according to the U.S. Bureau of Offshore Energy Management records.
Eni produces at Nikaitchuq from wells both onshore and offshore, from an artificial gravel island built in shallow waters. The exploration wells would likely be drilled from a rig on the gravel island.
Extended-reach exploration and production wells have been drilled for years on the Slope, typically from onshore drill pads to reach prospects or discovered deposits that are nearshore. BP has drilled several ERD wells from onshore that are three to four miles in lateral reach as part of its Niakuk field development.
However, plans went awry on BP’s plan to develop Liberty, a known offshore accumulation, using very long ERD wells. There were technical problems with a specialized drill rig built by BP and moved to the slope for the project. Also, changes in federal rules on deepwater drilling made following the Macondo accident in the Gulf of Mexico, which also apply to ERD wells, created complications on the Liberty plan.
BP subsequently sold part of Liberty to Hilcorp Energy, which now plans to develop the field using an offshore artificial island.
Schrader Bluff reservoir The producing oil reservoir for the Nikaitchuq field is in the upper Cretaceous OA sands of the Schrader Bluff formation, although the company has also been considering the development of oil from the Schrader Bluff N sands. Development at Nikaitchuq is challenging because of the compartmentalized nature of the sands and the relatively viscous 16 to 19 API oil. Eni has been using a combination of horizontal injection and production wells, employing both electric submersible pumps and water injection to boost oil production. The company has also been drilling horizontal, multilateral sidetrack wells that undulate their way through the sand bodies.
Brookian rocks The Schrader Bluff formation is part of the Brookian sequence, the youngest and shallowest of the North Slope petroleum-bearing rock sequences. The Brookian is known to extend a long way out over the Beaufort Sea continental shelf across older rocks that have been faulted into some major fault blocks. Brookian sands are thought to thicken in more downthrown rock sections between major faults.
Eni is presumably optimistic that the productive reservoir sands in the existing Nikaitchuq field continue north beyond the state Nikaitchuq unit.
- TIM BRADNER & ALAN BAILEY
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