Sleipner well pays off

November 15, 1999, 08:00 CET

An operation in a well on Statoil's Sleipner East field has boosted daily condensate production by 3,750 barrels to 101,250.

The group's additional earnings since completing the operation in September 1998 already total some NOK 210 million, reports Bodil Fjæreide Sømme, who is responsible for production follow-up.

Work cost only NOK 10 million, and this amount was recovered in about 20 days.

Well A-10 is one of 14 producers on the North Sea field, producing gas and condensate from Ty sands laid down in the Tertiary period.

Lean gas is being injected into the Ty formation to maintain pressure and thereby prevent condensate from liquefying. The injected gas also causes liquefied condensate to re-vaporise.

Close to A-10, lean gas gets injected into the deepest parts of the reservoir. Before the operation, this well produced only from the uppermost zones.

Since lean gas is lighter than the reserves in the field, A-10 began producing large volumes of the injected lean gas as early as 1997. To prevent this, the uppermost producing interval in the well was isolated and deeper layers were perforated.

Produced gas from the deeper intervals have not been contaminated by injected lean gas. Condensate recovery from the well has accordingly shown a substantial increase.

"We've had no lean gas breakthrough in the well since September 1998," reports Ms Sømme. "This means that it's continuing to produce rich gas, which also contains condensate."

She reports that Statoil is considering the same operation in other production wells on Sleipner East.