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Shell puts Burger at top in Chukchi Company want to drill up to three wells in three prospects, but known Burger gas pool will get priority treatment in 2010 program Alan Bailey Petroleum News
With $105 million placed on the table at the Chukchi Sea lease sale in February 2008 for just one of the tracts around the old Burger well, some 80 miles offshore the western end of Alaska’s North Slope, it’s fair to assume that Shell has more than a passing interest in the 25-mile-diameter Burger structure that is thought to hold perhaps 14 trillion cubic feet of natural gas.
So it perhaps comes as no surprise that Burger appears at the head of three Chukchi Sea prospects that Shell says it wants to test with a drill bit during the 2010 open water drilling season, according to the company’s 2010 Chukchi Sea exploration plan, recently put on public display by the U.S. Minerals Management Service. MMS has deemed the plan complete and is now in the process of determining whether to authorize it.
Three wells, five sites In the interests of flexibility, in the face of uncertain ice conditions, uncertain weather and uncertain drilling results during the drilling season, Shell plans to permit five Chukchi Sea drilling sites for 2010, although the company will not drill at more than three of those sites. Three sites are in the Burger prospect; one site is in the Crackerjack prospect, about 110 miles offshore; and the other site is in the Southwest Shoebill prospect, about 20 to 30 miles southwest of Crackerjack.
The old Burger well, drilled in 1989-90 to a depth of 8,202 feet, discovered a major gas field in a 107-foot-thick sandstone unit occupying a huge dome-shaped structure. Although MMS has estimated that the structure may contain 14 trillion cubic feet of natural gas, the agency has said that there could be anywhere from 2 trillion to 63 trillion cubic feet of gas in the field. The high level of uncertainty in the estimate reflects the fact that only one well has penetrated the structure.
The Crackerjack prospect, located on the flank of a huge fault structure, was the target of a Shell well drilled in 1990-91 — Shell’s proposed new well site appears to be more that 20 miles southwest of that old Crackerjack well. The Southwest Shoebill prospect has not previously been drilled.
According to MMS the Crackerjack area has several potential exploration plays involving rock units in what geologists refer to as the Ellesmerian and Beaufortian sequences. The original Crackerjack well sought oil in similar Ellesmerian rocks to those of the Prudhoe Bay oil field in the central North Slope. However, despite encountering oil and gas in some sandstone units, the well failed to make a commercial find.
Interplay of factors In its exploration plan Shell says that the order in which it drills Chukchi sea wells during the 2010 open water season will depend on a “complex interplay” of factors such as ice conditions; regulatory restrictions on when operations can be carried out; and the results of the drilling.
But it is clear that Burger is the company’s primary target.
“Given favorable conditions, it is anticipated that the initial drilling activity will begin at the Burger prospect,” the plan says. “If Burger is not accessible, then the next preferred location to begin the exploration drilling, if favorable conditions exist, is at the Southwest Shoebill prospect.”
The company will drill at Crackerjack initially, if that prospect is open but the other two prospects are inaccessible.
“(But) it should be noted that the focus of the 2010 drilling program will be shifted immediately to the Burger prospect as soon as it becomes safe to anchor and operate the drillship on that prospect,” the plan says. “Given favorable drilling performance and subsurface results at the initial Burger drill site, another of the permitted drill sites in the Burger prospect may be the next well drilled.”
And the total number of wells drilled will depend on the ice conditions and the length of time available for operating in the Chukchi. Shell says that it plans to use the ice-reinforced drillship, Frontier Discoverer, for the drilling, moving the drillship into the Chukchi Sea around July 1, ready to start drilling around July 4. Drilling operations will end by Oct. 31.
Shell has previously said that it also plans to use the Frontier Discoverer to drill two wells in the Beaufort Sea in 2010. So, presumably the company will shuttle the drillship and its attendant fleet of support vessels across to the Beaufort Sea for part of the drilling season.
Oil spill response The support fleet will include an on-site oil spill response vessel with sufficient oil storage capacity to handle the first 24 hours of any oil spill emergency. An Arctic oil storage tanker with capacity to handle at least a 30-hour well blowout will be staged within a 24-hour sailing time of an active drill site. And an additional oil spill response barge and tug will be positioned ready to respond to any spilled oil that might reach the nearshore area of the Chukchi.
Shell also has a plan for dealing with a well blowout, including the possibility of drilling a relief well to plug the oil flow.
However, Shell says that any kind of oil spill is very unlikely. In addition to using state-of-the-art well planning and drilling techniques, including the use of remote operations centers for monitoring what is happening at the drill site, the company has a critical operations and curtailment plan that specifies situations such as severe weather, in which drilling would stop, with the drillship perhaps moving off site.
Marine mammals Shell also says that it is voluntarily submitting to MMS a site-specific plan for monitoring marine mammals, including the use of marine mammal observers onboard vessels, the use of subsea acoustic recorders and the carrying out of aerial surveys along a zone that extends about 20 miles out from the Chukchi Sea coast. And, as part of applications to the National Marine Fisheries Service and the U.S. Fish and Wildlife Service for authorizations for the nonlethal, incidental take of marine mammals, the company has specified how many animals of various species might be exposed to significant sound from its drilling activities.
“Any impacts to whales and seals from the planned exploration drilling program would be temporary and result in only short-term disturbance or displacement,” the plan says. “From a historical perspective, the temporary activity of offshore exploration drilling and associated support vessel activities, collectively and individually, have not resulted in impacts of biological significance to marine mammals of the Arctic, or interference with the subsistence harvest of those marine mammals by the residents of the communities along the Beaufort and Chukchi Seas.”
Shell says that it has prepared a plan of cooperation with Chukchi Sea coastal communities that depend on the subsistence hunting of marine mammals.
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