The Aurora Oil Pool ("AOP") is located within the current boundaries of the Prudhoe Bay Unit ("PBU"), and it occurs within the Kuparuk River Formation (“Kuparuk”). The pool was discovered in 1969 by the Mobil Oil Corporation Mobil-Phillips North Kuparuk State No. 26-12-12, where the accumulation lies between the depths of 6,765’ and 7,765’. The structure lies between 6450' and 6850' true vertical depth below sea level. Regular production from the field began in November 2000, and regular water injection began in December 2001. Production peaked at just over 14,000 barrels of oil per day (BOPD) during August and September of 2006, and then began to decline. For the second quarter of 2011, production averaged 7,900 BOPD.

Within the Aurora pool, the Kuparuk comprises Early Cretaceous-aged marine shoreface and offshore sediments consisting of very fine to medium grained, quartz-rich sandstone with interbedded siltstone and mudstone. The Kuparuk is stratigraphically complex, characterized by multiple unconformities, changes in thickness and sedimentary facies, and local diagenetic cementation. In the AOP, the Kuparuk reservoir is divided into three stratigraphic intervals, that are named, from deepest to shallowest, A, B and C. The A interval contains two reservoir quality sub-intervals, the A-4 and A-5 sands, which are typically 30’ and 20’ thick, respectively. The B interval is dominated by siltstone and sandy mudstone with numerous discontinuous thin sandstone lenses, which are up to 3’ thick. The C interval contains the primary reservoir sands of the pool, and it consists of thick, amalgamated sands, with high net to gross ratios. Average layer properties range between 16% for the A sand net pay interval, and 25% for C sand net pay intervals. The average permeabilities for these layers range from 12 md to 158 md. The AOP structure is a NW to SE-trending ridge that is broken by N-S trending faults having vertical displacements ranging up to hundreds of feet. The traps for oil and gas are created by a combination of structural and stratigraphic features: the accumulation is bounded to the W by several faults, to the E and SE by unconformities, and to the SW and N by oil-water contacts. The reservoir is compartmentalized, and fluid contacts (oil-water and gas-oil) appear to be variable across the pool. The reservoir temperature is about 150 degrees F at 6700’ true vertical feet subsea. Oil gravity ranges from 25.2 to 29.1 degrees API.