Statoil reports finds on Tyrihans South, North Sea Dolly fields; spuds well on Blåmeis

By OGJ editors
HOUSTON, Nov. 27 -- Statoil ASA recently proved more oil and gas in the Tyrihans South discovery in the Norwegian Sea and has found oil in its Dolly prospect in the Tampen area of the North Sea, the company said.

It also expects to find oil on Blåmeis prospect—also in the Norwegian Sea—where it spudded an exploration well Tuesday, reported Knut Chr Grindstad, exploration vice-president for the Halten-Nordland complex in the north Norwegian port of Harstad.

Tyrihans South
The Tyrihans South appraisal well, drilled by Stena Don to 4,000 m TD last month, is currently being logged.

"At the moment, it looks as if our optimistic estimates (for Tyrihans South) have been confirmed, but we'll know more when the data have been gathered," said Grindstad. He added that the results appeared "gratifying."

The additional resources proven would add substantially to total reserves in Tyrihans South and North fields.

"We need a number of such discoveries in future to keep our processing facilities fully occupied and to continue developing the area," said Grindstad.

Tyrihans is a satellite of Statoil's producing Åsgard field, and once the basis for future production has been clarified, Statoil said, the most natural approach for development would be a direct subsea tie-in with the existing infrastructure on Åsgard.

Dolly
The Deepsea Trym drilled the 34/10-47S wildcat well on Dolly prospect 5 km north of Gullfaks satellites Gullveig and Rimfaks in the North Sea. A project team is now evaluating results from the well, which encountered hydrocarbons.

In drilling this well, Statoil employed an innovative technology, which it has used previously on some of its production wells in other North Sea fields, to complete the well more rapidly than usual.

The well path passes—in the form of a curve—through a Brent formation prospect, parts of which lie more than 2,500 m below sea level. After initially descending vertically, it angles out, becomes gently horizontal and then ascends at an angle of 106°.

A Powerdrive drilling machine developed by Anadrill Schlumberger was used for the operation. The unit is computer controlled and can drill longer stretches at a time, reducing the time required for well completion.

This approach is not unusual for production wells, but the Dolly wildcat is one of the first exploration wells drilled by Statoil to use the method. "Viewed purely in terms of drilling technology, it's all the same whether you're drilling a producer or a wildcat," said Bengt Beskow, exploration manager for the Tampen area.

"When we're looking for supplementary oil on the fringes of mature fields, in satellites or in new areas like the Dolly prospect, however, we must try to rationalize drilling operations."

Beskow noted that two other recent Statoil exploration wells, in the Ole and Dole structures west of Gullfaks satellite Rimfaks, also utilized new methods. Hydrocarbons were proven earlier this year in the two structures—3/9-8A Ole and 33/9-8S Dole.

"These are positive results," said Reidar Helland, manager of the Gullfaks resource development department.

"Possible solutions for development as supplementary resources to the major Tampen area fields will be evaluated during the winter."

Blåmeis
Stena Don spudded the first Blåmeis prospect exploration well, which is expected to reach its TD of 2,000 m around Dec. 26.

Blåmeis is east of Norne field in an area where Statoil has found oil in a series of structures named after birds—Stær (Starling), Falk (Falcon), and Svale (Swallow). None of these discoveries, however, is large enough to support a stand-alone development. Statoil even downgraded estimated reserves of Svale in fall 2001 to 50 million bbl from its previous estimate of 80 million and postponed filing a development plan (OGJ Online, Sept. 17, 2001).

Statoil therefore is considering other options, such as developing technology facilitating the tieback of small finds to Norne's floating production, storage, and offloading vessel. Developing these oil and gas discoveries as a cluster would improve their economics, and the Norne vessel will need additional oil to maintain production levels, as it is due to go off plateau in 2003.

Consequently, Statoil is attaching great expectations to the Blåmeis wildcat, Grindstad said. An oil discovery there could either be tied back to Norne, or the field could become a stand-alone development if the well confirms Statoil's optimistic hopes.

Statoil said it suspects that Blåmeis oil, if found, would be heavier than Norne crude, but that would not be determined until drilling is completed and results analyzed.

If it is, Statoil may have an ace in the hole— a new type of bacteria that it developed jointly last year with the University of Bergen and Austrian oil and gas company OMV AG—and which Statoil patented—to create a surfactant in the oil, which Statoil said can improve production (OGJ Online, Feb. 8, 2002). Norne field was selected for the 5 million kroner full-scale pilot use of the bacteria because oxygen is not removed from water injected into its reservoir due to the use of stainless steel in its subsea installations. Statoil earlier this year said it would build a fertilizer plant on the Norne FPSO to grow the bacteria for use in Norne.

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