Commissioner points to differences between offshore Alaska and Gulf of Mexico
BY ALAN BAILEY FOR GREENING OF OIL
Shell’s Alaska Vice President Peter Slaiby in front of the Nanuq, the purpose-built, ice rated oil spill response vessel that Shell commissioned for Arctic use. The company plans to use the drillship Noble Discoverer to drill OCS leases in the Beaufort and Chukchi seas in 2011 and has planned to use that same drillship to drill a relief well, should a well blowout occur. Because of heightened concerns about the practicalities of relief well drilling, Shell is going to use the Kulluk as a standby rig for drilling a relief well, should the need arise, Slaiby said.
As the reverberations from the Gulf of Mexico oil spill disaster continue to shake the U.S. oil industry and those who regulate it, Tom Irwin, commissioner of the Alaska Department of Natural Resources, or DNR, is anxious to point out some key differences between drilling in the Gulf and drilling in the seas offshore Alaska’s Arctic coast.
In a guest editorial for a biannual sister publication of Greening of Oil, Irwin emphasized that Alaska state land — both onshore and offshore — remains open for oil and gas development.
“With all the attention given to offshore drilling in the past year, it is important to realize the regional differences associated with offshore exploration and drilling,” Irwin said.
DNR is the Alaska administration’s department responsible for promoting oil and gas development on state lands, including state offshore waters out to a distance of three miles from the coastline. The outer continental shelf beyond that three-mile limit comes under federal jurisdiction.
Arctic Alaska offshore has shallow water
A key difference between the Arctic Alaska offshore and the Gulf of Mexico is the water depth, Irwin said. Whereas BP’s infamous Gulf of Mexico Macondo well lies beneath 5,000 feet of seawater, water depths in the state waters of the Beaufort Sea, for example, range up to a maximum of 65 feet, Irwin said. And even in the outer continental shelf of the Beaufort Sea, oil and gas leases have traditionally been located in areas with water depths less than 330 feet; all current outer continental shelf Chukchi Sea leases are in water depths around 130-160 feet, he said.
In fact all three operational oil fields offshore in the Beaufort Sea — the Northstar, Oooguruk and Endicott fields — use directional drilling techniques from man-made gravel islands and are closely similar to onshore fields.
And if exploration drilling occurs from floating drilling rigs, the shallow water depths in the Arctic substantially ease access to subsea wellheads.
“Despite the cold ocean water temperatures, human dive teams are able to operate directly on the seafloor in many places in offshore Alaska, whereas highly specialized remotely operated vehicles are required to investigate and respond to incidents at the seabed in deepwater Gulf of Mexico operations,” Irwin said.
Alaska operations are seasonal
The sharp contrast between the biting cold of the Arctic winter and the few months of the summer when sea-ice recedes toward the North Pole causes Arctic offshore oil exploration and development activities to take on a strong seasonal character, as distinct from the Gulf of Mexico where offshore industrial activity of all types can continue pretty much year round.
“Some Alaskan exploration prospects are better drilled in the winter from bottom-founded drilling caissons or man-made ice islands, both firmly anchored to the seabed throughout the drilling season,” Irwin said. “Other Alaskan prospects are drilled from floating drill ships or jack-up rigs in the open water of late summer.”
Drilling projects in the Arctic often involve the use of icebreakers to manage any ice floes that might threaten the drilling operations, although ice activity can interrupt the drilling and cause a drill rig to move offsite temporarily, in the same way that storms can sometimes interrupt Gulf of Mexico drilling.
And government regulators enforce stipulations that limit activities at times when broken sea ice is present, when cleaning up an oil spill could prove especially difficult, Irwin said.
Pressures tend to be lower in Alaska rocks
Then there are the contrasts in geology between the Gulf of Mexico and the Alaska Arctic.
“Much of the Gulf of Mexico is a region marked by rapid and recent deposition of alternating sands and muddy sediments that, with deep burial and compaction, lead to strongly over-pressured pore fluids,” Irwin said.
High drilling mud pressures used to control these high overpressures in Gulf wells can cause fractures in the subsurface rocks, leading to potential loss of well fluids that could trigger a well blowout, he said. The same rapid sediment deposition and resulting overpressures are not believed to be present in the Alaska Arctic offshore, Irwin said.
AOGCC provides independent oversight
And the Alaska Oil and Gas Conservation Commission, or AOGCC, a quasi-judicial state agency operating independently from DNR, regulates the drilling of wells in Alaska state waters. Regulation includes the permitting and inspection of drilling operations and equipment.
The separation between DNR and AOGCC has “helped alleviate potential conflict between the state’s revenue interests in achieving total ultimate recovery on state leases, with the equally important conservation interest of ensuring the most prudent oil field practices are routinely performed,” Irwin said.
AOGCC geologists review the geology of the strata where a well is being drilled, with AOGCC engineers then reviewing the suitability of the drilling fluids planned for use in the well. And AOGCC mandates certain standards for well design and requires confirmation that a drilling operation will follow good working practices, Irwin said.
An AOGCC inspector checks the condition of each drilling rig before the rig is brought into service. And the state mandates the testing of blowout preventers every seven days for exploration wells, and every 14 days for other wells, with AOGCC inspectors witnessing about 25 percent of the tests, Irwin said.
Alaska offshore has substantial resources
The substantial oil and gas resources in Alaska’s state waters are important to the United States’ energy future and can help stem the decline in domestic production, Irwin said.
“As Alaskans, we rest assured that the expertise our agencies possess, and the regulatory framework this expertise has created, and continues to create, will be appropriate and sufficient for us to invite prudent operators to produce our hydrocarbon resources while protecting our other natural resources,” he said.
Alan Bailey can be reached at firstname.lastname@example.org
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