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Eni applies for injection at Nikaitchuq Tells AOGCC it expects to need to begin water injection by Jan. 10 to maintain reservoir pressure at North Slope offshore field Kristen Nelson Petroleum News
Eni US Operating Co. has applied to the Alaska Oil and Gas Conservation Commission for an area injection order for its Nikaitchuq unit development project, and told the commission it anticipates needing to begin injecting water on or before Jan. 10. The commission has tentatively scheduled a public hearing on the application for Jan. 6, but said that if it receives no requests for a hearing it may consider issuance of an order without a hearing.
Eni has been targeting startup for late 2010 or early 2011. Nikaitchuq will be the first North Slope field not operated by one of the North Slope majors to have its own crude oil processing facilities.
Eni told the commission it plans to apply water injection from the beginning of production to maintain reservoir pressure.
The Nikaitchuq field is offshore the North Slope near Oliktok Point in the shallow waters of the Beaufort Sea with eventual development from both an onshore drilling site at Oliktok Point, where the field’s processing facilities are located, and from an offshore drilling island. The processing facilities have a capacity of 40,000 barrels per day.
Initial production will be from the onshore drill site; drilling is scheduled to begin in 2011 at the offshore drill site.
21 injection wells planned Eni told the commission all proposed injectors are single lateral horizontal wells, with eight planned from the Oliktok Point pad and 13 from the offshore drill site near Spy Island.
Ten producers, three water source wells and one disposal well are also planned from the onshore drilling pad; 16 producers and one disposal well are planned for the offshore drilling island, which is connected to Oliktok Point with a three-mile subsea flowline and utility bundle.
Both producers and injectors will be horizontal wells with laterals ranging from 4,000 to 8,500 feet, the company said. Producers and injectors will be paired and in most cases producers will be the outboard wells.
Electric submersible pumps will be used to artificially lift the oil to the surface.
Initially water from Ivishak formation source wells will be the primary water source for injection, but over time, Eni said “a mixture of Ivishak water and Schrader Bluff produced water will be the primary water source.” The maximum water injection rate is expected to be 6,000 barrels per day, with an average injection rate of 1,500 bpd.
Main reservoirs at Nikaitchuq are the OA and N Cretaceous sands within the Schrader Bluff formation, Eni said in its injection application, although minor oil accumulations have been tested in the Triassic Sag River sandstones.
Nikaitchuq development is based on exploitation of the OA reservoir, but Eni said N sand and Sag River potential will be re-evaluated based on drilling results and further evaluation of the 2008 seismic acquisition.
Viscous oil The Schrader Bluff OA sand hydrocarbons are viscous oil with API gravities from 16 to 19. A production test at the OP-12 well was 2,000 bpd on electric submersible pump lift.
Original oil in place for the Schrader Bluff OA reservoir is estimated at 800 million to 930 million barrels, with a median of 870 million barrels.
Potential 30-year technical recovery ranges from 15 percent to 22 percent of OOIP, Eni told the commission.
“The economic recovery percentage could be substantially lower than the technical recovery percentage, depending on economic assumptions in the future,” Eni said.
Waterflood represents a 10 percent to 18 percent increase in recovery compared to primary depletion which, the company said, would be only 4 percent to 5 percent of OOIP.
Eni said no well tests are available for the N sand, but said it is evaluating options for acquiring a fluid sample from the N sand.
Estimates of original oil in place for the N sand are 300 million to 600 million barrels.
New 3-D shot in 2008 Three 3-D seismic surveys and some 2-D seismic lines are available for Nikaitchuq, Eni said, with the main seismic data set used to define the Nikaitchuq field a 3-D volume merged with data sets from Simpson Lagoon and Thetis Island.
There was initially very sparse coverage for the southern portion of Nikaitchuq, so Eni contracted a proprietary 3-D survey that was shot by seafloor cable array during the 2008 summer open water season.
Eni said the 2008 survey area was smaller than planned due to logistical issues, but did cover the most critical area for the development and data was collected in the gap between two existing surveys.
The Nabors 245E rig, currently under contract to Eni, will be used for development drilling at Oliktok Point. Eni said the rig will be used for both drilling and workover operations and can perform workovers on failed ESP producers.
Eni said it plans to use the Doyon 15 rig for development drilling on the offshore drill site, and anticipates mobilizing the rig by barge in the summer season of 2011.
Eni became a 30 percent working interest owner at Nikaitchuq in August 2005 when it acquired the Alaska assets of Armstrong Oil & Gas Alaska. The unit was expanded in July 2006 to include the former Tuvaaq unit and other leases. At the beginning of 2007 Eni acquired Kerr McGee’s 70 percent working interest and became the unit operator.
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