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Light intervention boosts recovery

November 2, 2004, 09:00 CET

The two first light well interventions in this year’s campaign have been completed by Statoil as part of its efforts to improve recovery from Norwegian subsea fields.

These producers on Åsgard in the Norwegian Sea were recently logged from the Seawell vessel owned by WellOps in order to boost reservoir understanding by identifying their flow properties.

Light well intervention involves wireline-based workovers, with the line run directly through the sea to a well which remains under pressure.

This eliminates the need for the risers required when such work is carried out from a drilling rig, while a ship can also be redeployed much more quickly than a semi-submersible.

Statoil has achieved savings of roughly 50 per cent by replacing a rig with a vessel like Seawell.

“Light well intervention will be an important tool for improving the recovery factor in subsea wells from today’s 43 per cent to 55 per cent,” says Øyvin Jensen.

He is Statoil’s manager for drilling and subsea operations in the Tampen area of the Norwegian North Sea.

Light intervention operations are planned in a total of 17 wells during this year’s campaign, with each job scheduled to take from six to 14 days.

This year’s activities are shared between the Tampen and Halten/Nordland business clusters.

In addition to Åsgard, they embrace the Vigdis subsea development in the North Sea as well as satellites of the Statfjord and Gullfaks fields in the same waters.

A similar campaign was conducted in three wells with the Regalia multipurpose support vessel last year.

The contract with WellOps provides options for carrying out similar operations in 2005.

These are due to cover about 15 wells, reports Mr Jensen. He adds that the scope of such work is unlikely to decrease in coming years.