KUPARUK ANNIVERSARY: Kuparuk discovery made by Sinclair at Ugnu No. 1

The Kuparuk oil field was discovered in 1969 when Sinclair Oil and Gas and BP drilled the Ugnu No. 1 and tested 1,056 barrels per day of oil from the Kuparuk formation.

Sinclair was an acquisition target of Gulf and Western. O.P. “Pen” Thomas, then Sinclair’s president, said it would not have been a good deal for the company’s shareholders.

“We moved quickly and cut a deal with Atlantic Richfield to stave off Gulf and Western,” Thomas told the ARCO Spark, the company newsletter, in a 1982 interview.

Before Sinclair became a part of ARCO in 1969, it spud the Kuparuk discovery well on the North Slope.

Sinclair’s Colville No. 1, drilled in 1965-66, had been a dry hole.

At Ugnu No. 1, however, the company discovered Kuparuk.

Christopher Lewis related in a 2006 talk that Sinclair’s desire for a successful well on the North Slope was tied to the possibility of acquisition by Gulf and Western. “The thinking was that if we would spud a well, our stock would go up and Gulf and Western wouldn’t get us,” he said.

Well named for nearby river

That name is carried today by the shallowest and most viscous of North Slope oil formations.

The fame of the Ugnu No. 1, however, is not the formation of that name, but as the discovery well for the Kuparuk River field.

Lewis said the discovery was a surprise and led to a reevaluation of the area’s geology.

“We were drilling at 6,000 feet without any hope of getting anything because we were downdip” from the earlier well, a dry hole, he said. “I was having my dinner when the crew said we had had a break,” an increase in the rate of penetration as the drill bit encountered porous layers of rock.

“When I looked at the cuttings, I realized that we had an excellent oil sand,” Lewis said.

“Our surprise was complete when the test produced oil,” he said. “We recovered oil at a rate of about 1,000 barrels per day at that well.”

—Kristen Nelson