Breaking with tradition: Alaska exploration heads north of the Barrow Arch with Shell and ConocoPhillips winning U.S. Minerals Management Service leases well to the north of traditional North Slope plays.(CHAPTER TWO--EXPLORATION PLAYS)

Publication: Oil and Gas Investor

Publication Date: 01-OCT-05

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COPYRIGHT 2005 Hart Publications, Inc.

Traditional exploration plays in northern Alaska have largely focused on a structural high called the Barrow Arch, a subsurface tectonic "bump" that runs southeast from Barrow, parallels the Arctic coastline, goes right through Prudhoe Bay and points directly at the 1002 area of the Arctic National Wildlife Refuge (ANWR).

The two largest oilfields in North America, Prudhoe Bay and Kuparuk River, lie along the arch, as does Alaska's newest producing oilfield, Alpine. All North Slope production comes from fields on or just south of the arch, even BP Exploration (Alaska) Inc.'s Northstar field, which is the furthest north producing field in Alaska. Northstar facilities are on Seal Island in federal waters north of Prudhoe Bay.

The 202-million bbl Northstar oilfield produces oil from the Ellesmerian Ivishak Formation that forms the main reservoir at Prudhoe because rift-related fault blocks on the northern flank of the Barrow Arch trapped the reservoir sand.

Fields like Prudhoe and Endicott lie on the arch in a rock sequence known as the Ellesmerian. Other fields like Kuparuk and Alpine lie in another sequence known as the Beaufortian. The Ellesmerian sequence consists of strata ranging in age from Devonian to Jurassic, while the Beaufortian sequence ranges from Jurassic to early Cretaceous.

TIME TO EXPLORE NORTH

Currently, exploration in northern Alaska is moving west into the National Petroleum Reserve-Alaska (NPR-A) along and just to the south of the Barrow Arch.

If the 1002 area of ANWR is opened to drilling, exploration also will move east...

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