The Kuparuk River Oil Pool was discovered in 1969 by the Sinclair Ugnu No. 1 well.  This pool is the second largest on the Arctic Slope of Alaska, occupying approximately 500 square miles.  It is defined as the accumulation of oil that is common to, and correlates with, the accumulation found in the ARCO West Sak River State No. 1 well between the measured depths of 6,474 and 6,880 feet.   The pool lies from approximately 5,600’ to 6,500' true vertical depth subsea.   Kuparuk oil has an average API gravity of 24 degrees.  Step-out exploratory drilling of the Palm #1 and #1A wells in during 2001 discovered an extension of the pool to the west of the main pool.  This discovery added 74 million barrels of original oil in place (“OOIP”).   OOIP for the entire pool is estimated at 5 billion STB.  Regular production from the pool began in December of 1981, and waterflood operations were initiated in February 1982.  Production from the pool peaked in December 1992 at an average of 339,386 barrels of oil per day (“BOPD”), and has steadily declined to its current level of 144,350 BOPD from 461 production wells in December 2004.

The Kuparuk River Formation is a sequence of clastic sediments deposited on a shallow marine shelf during Neocomian (Early Cretaceous) time.  The formation is divided into Upper and Lower Members. These two Members are comprised of four informal units that are termed, in ascending order, "A", "B", "C", and "D". The "A" and "C" units are the pay-bearing intervals.  The A unit exists throughout the pool area, and it consists of sandstone, siltstone and mudstone in a series of regressive cycles that range to 70’ thick.  When mapped in detail, these individual cycles form elongate bodies that strike northeast-southwest.  Porosity averages 23% and permeability averages about 80 md.  The A unit thins to the west where it is truncated by an intraformational unconformity that lies at the base of the C unit.  The C Unit is composed of glauconitic sandstone and siltstone with subordinate conglomerate and lesser shale.   Bands of siderite-cemented sandstone are common.  Porosity and permeability average 21% and 90 md, respectively.  Throughout the Kuparuk River Unit, C-unit sand deposition appears to have been influenced by syndepositional, northwest-trending normal faults.