Statoil's Sleipner Delineation Delivers Gas Pay

Statoil, operator of the Sleipner Vest field in production licenses 29 and 46, has completed the delineation of the gas/condensate discovery 15/9-B-1 (Beta Vest).

The discovery was proven during the autumn of 2009 in Middle Jurassic reservoir rocks (the Hugin formation) about 1.5 kilometers west of the Sleipner Vest field and four kilometers from the Sleipner B platform. The 15/9-B-1 discovery well was drilled to the south on the top of the Beta Vest structure and there was uncertainty regarding the distribution of petroleum north and west on the structure. Before the appraisal wells were drilled, the operator's resource estimate for the discovery was between six and ten million standard cubic meters (Sm3) of recoverable oil equivalents.

The purpose of the wells was to delineate the 15/9-B-1 discovery. Three appraisal wells, 15/9-B-8, -8A and -8D, were drilled about two kilometers north of the discovery well. B-8, which was drilled at the bottom of the structure, encountered a 29-mete oil column and a 12-meter gas column in the Hugin formation. B-8A, deeper in the structure, was water-filled. B-8D, towards the top of the structure, encountered a 117-meter gas column in the Hugin formation. Two appraisal wells, 15/9-B-8B and -8C, were drilled in the southern end of the structure near the 15/9-B-1 discovery well. B-8B, near the top of the structure, encountered a 53-meter gas column in the Hugin formation, while B-8C, further down on the structure, was water-filled.

None of the wells were formation-tested, but data acquisition and sampling were conducted. The preliminary size of the discovery has been estimated at 13 million Sm3 recoverable oil equivalents. The gas has a gas/condensate ratio of about 2000 Sm3/Sm3 and a CO2-content of at least 14 per cent, which is higher than in the Sleipner Vest field. The discovery is being prepared for production via the Sleipner Vest field.

Production licenses 29 and 46 were awarded in the 2nd and 3rd licensing rounds in 1969 and 1976, respectively. 15/9-B-8 was drilled to a vertical and measured depth of 4000 and 6692 meters below sea level, respectively, and was terminated in the Skagerrak formation in the Upper Triassic. 15/9-B-8A, -8B, -8C and -8D were drilled to vertical depths of 3899, 3701, 3856 and 3700 meters, respectively, as well as measured depths of 7418, 6417, 7107 and 5724 meters below sea level respectively, and were all terminated in the Hugin formation. Water depth at the site is 108 meters. Four of the wells have been plugged and abandoned, while 15/9-B-8D at the top of the Beta Vest structure will be a development well.

The wells were drilled by the West Epsilon drilling facility, which is connected to the Sleipner B platform. Over the course of the spring, the rig will be demobilized and prepared for drilling development wells at the Gudrun field where Statoil Petroleum AS is the operator.

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