Offshore staff

(Alaska)-BP Alaska Exploration Inc. is considering a "super rig" to drill potential record-breaking extended-reach wells to produce the Liberty oil field, located 5 mi off Alaska's northern coast. Liberty is in federal Outer Continental Shelf waters in Foggy Island Bay, east of the large Prudhoe Bay oil field.

Liberty is still being studied, but BP's current plan involves producing the field from wells drilled from shore rather than building an artificial gravel island offshore. If implemented, wells reaching Liberty's underground reservoir from shore would have to be drilled as far as 40,000 ft laterally from the surface location of the rig, making it a world-record. BP is also the current record holder, with 35,000-ft lateral wells at its Wytch Farm oil field in the UK.

Lateral drilling technology in the industry has rapidly progressed since the early 1990s, when the limits of extended-reach wells were about 16,000 ft. However, Liberty's oil reservoir is also about 11,000 ft below the surface, which means that the drill rig would have to be able to lift about 8 mi of steel pipe out of the ground.

BP Alaska Wells and Drilling Manager Gary Christman says this distance is well beyond the capability of the big drill rigs currently on the North Slope. To drill the wells, BP would have to undertake major modifications to one of the rigs on the Slope or build a new rig big enough to effectively lift 1.5 million to 2 million lb. The largest rigs on the Slope now can handle one-half to one-third that amount.

If a new super-rig is built it would look much like a conventional rig with a drill mast about the same height. The difference is that it would have a squat appearance, with more steel around the base to add strength.

Daryl Luoma, BP's development manager for Liberty, said if the proposal moves ahead, engineering would likely take place in 2007, and permit applications would be made in 2008. Fabrication of needed equipment, including the new rig or modification to an existing rig, would take place in 2008 to 2010.

Liberty's first production with the super rig would occur in 2010 or 2011, Luoma said.

BP acquired the field from Shell in September 1996. Shell had built an artificial island called Tern Island over the field, but initial results from a discovery well were not economically promising with the available technology. BP finally shelved the idea of developing the field with an offshore island in August of this year.

The company is considering drilling from two possible locations on shore, one at Point Brower near the existing Endicott field, and the other at the East Kad site, an old exploration well location farther to the east. If Point Brower is selected production wells will be drilled to the east, and the oil would be processed in the Endicott field production facility.

If East Kad is the preferred location, wells would be drilled to the north and the oil would be processed in the Badami field production facility. According to Luoma, there is ample room in Badami's processing plant for Liberty oil, although some modifications will be needed to the plant.

11/03/2005