The Endicott-Ivishak Oil Pool of the Endicott Field (“Endicott-Ivishak”) lies beneath the Beaufort Sea and within the Duck Island Unit, about 8 miles east of Prudhoe Bay Unit (“PBU“). The Sag Delta No. 9 exploratory well (since renamed DIU MPI 5-03/SD09) discovered this pool in 1982. This pool is the accumulation of hydrocarbons that is common to, and correlates with, Sag Delta No. 9 between the measured depths of 12,069’ and 12,314’. The Endicott-Ivishak Oil Pool has been developed from the Main Production artificial island (MPI) that is located approximately 4 miles offshore in 2 to 14 feet of water.

The pool has been producing continuously since July 1989. During the peak production years from November 1990 and November 1991, Endicott-Ivishak production ranged from 12,308 to 5,005 barrels of oil per day (“BOPD”), and averaged about 7,270 BOPD. Between December 1991 and June 1993, production dropped to an average of 2,650 BOPD. Since July 1993, production has slowly declined. During the first six months of 2011, the pool averaged 265 BOPD from one production well Duck Island Unit 2-32/SD03.

The Endicott-Ivishak Oil Pool encompasses reservoirs assigned to the Triassic-aged Ivishak Formation, which is a member of the Sadlerochit Group. This formation was deposited in a marine shoreface environment. The pool is bounded to the south by a major fault and there appears to be numerous smaller faults within the accumulations. The pool encompasses an area of approximately 380 acres, and it appears to be separate from other, nearby accumulations based on pressure measurements and differences in oil gravity. The base of the Ivishak oil column appears to be planar, and is underlain by a tar mat, which separates the oil accumulation from the underlying aquifer. No gas cap has been observed. Oil gravity averages 25° API within the pool, and the temperature is 212°F at 10,000 feet true vertical depth.