THREE BIG NORTH SLOPE SURPRISES

LEWIS, Christopher J., P.O. Box 924, 2 Berry Lane, Ross, CA 94957, [email protected]

The author worked for BP Exploration (Alaska) and its associated companies. He participated in four geological field seasons in North Alaska (1964, 1966, 1967 & 1970). He was a rigsite geologist on Kuparuk Unit 1A in 1964, Colville # 1 in 1966 and Ugnu # 1 in 1968. He continued to be active in Alaska exploration until at least 1980.

The three great North Slope surprises he was closely associated with were: 1) the Surprise Creek Anticline; 2) the Kuparuk River Field; and 3) the Endicott Field.

In 1965, the author and Norman Johnson of Sinclair were walking up an, at that time, unnamed creek to map a section in the Kuparuk/Corwin escarpment. Suddenly, they noticed abundant pebbles of Triassic, thin-bedded limestones crowded with Monotids in the stream bed, and rounding a bend were confronted with a magnificent anticline in the Triassic almost adjacent to the Kukpowruk outcrop. This was quite a surprise, as the nearest exposure of Triassic Shublik was some 25 miles to the south. The author will offer suggestions as to how this maverick anticline became emplaced.

In 1967, just before Thanksgiving, the author was asked to go immediately to Alaska for Sinclair Oil Corporation to stake a well on BP-Sinclair acreage west of Prudhoe Bay. Sinclair was doing this to prevent it from being taken over in a hostile bid from Gulf and Western Industries. He chose a location between two distinctive-looking lakes, which he thought he could easily identify. Later when the well was drilling he arrived on the rigsite at about 6,000 feet just in time to witness the penetration of an oil sand. That was another mammoth surprise and it caused a rapid review of our geological understanding of the area.

Thirdly, in 1978, there was the discovery of the Endicott Field in a Devonian section that was essentially devoid of reservoirs close by at Prudhoe Bay. We did consider the possibility of reservoir enhancement close to the faulting that truncates the Prudhoe Bay Field to the north. This had occurred with the Sadlerochit. However, our urgency to drill was caused by the pending expiry of leases that were not protected by the Prudhoe Bay Unit.