Equinor Energy AS completed drilling appraisal wells 16/1-30 S and 16/1-30 A as part of delineation of the 16/1-29 S (Lille Prinsen) oil discovery in the North Sea (OGJ Online, June 11, 2018). Other segments in 16/1-29 S will be evaluated and further delineation of the oil discoveries is being assessed. Licensees also will assess earlier discoveries within the license, the company said. The wells have been plugged.
The wells were drilled about 1 km west of the discovery well—proven in 2018 in the Zechstein group from the late Permian period as well as in the Grid formation from the Eocene—by Seadrill’s West Phoenix semisubmersible drilling rig in the central part of the North Sea 200 km west of Stavanger in 113 m of water.
Prior to drilling the appraisal wells, the size of the discovery was 2.5-5.5 million standard cu m of recoverable oil.
The earlier 16/1-6 S Verdandi oil and gas discovery—made in the same license in 2003—was in the Heimdal formation in the Palaeocene and in the Grid formation in the Eocene (OGJ Online, May 22, 2003).
The primary exploration target for well 16/1-30 S was to delimit the 16/1-29 S oil discovery and to determine the oil-water contact in the outer wedge to the south. Licensees also wanted to investigate the possibility of reservoirs in the Triassic and Jurassic.
The secondary exploration target was to delineate 16/1-6 S Verdandi for a possible oil zone in the Heimdal formation and to investigate the petroleum potential in the Grid formation and to collect data in basement rock.
Well 16/1-30 S was drilled to a respective measured and vertical depth of 2,101 m and 2,018 m subsea. In the primary exploration target, it encountered an 18-m oil column in the Viking group from the Middle to Late Jurassic age, with sandstone layers totaling 2 m with moderate reservoir quality. The oil-water contact was proven 1,919 m subsea.
The secondary exploration target in the Heimdal formation was not encountered. In the Grid formation, the well encountered an oil column of 12 m, with 1 m of sandstone with moderate reservoir quality. Relatively dense basement rock was encountered.
The objective of well 16/1-30 A was to examine the extent of the carbonate reservoir in the Zechstein group from the Late Permian period, as well as to investigate the possibility of reservoir development in the Triassic and the Jurassic periods.
Well 16/1-30 A was drilled to a respective measured and vertical depth of 2,037 m and 1,952 m subsea. It encountered a 15-m oil column in the Viking group from the Middle to Late Jurassic, with sandstone layers with a total thickness of 6 m with poor to moderate reservoir quality. Oil was proved down to 1,914 m subsea.
The carbonate reservoir from the Late Permian period was not encountered. Additional volumes in the outer wedge of the Lille Prinsen oil discovery are estimated at 200,000-1 million standard cu m of recoverable oil.
These are the seventh and eighth wells in production license 167.
The wells were not formation-tested, but extensive data acquisition and sampling have been carried out.
The drilling facility will now move to production license 942 in the Norwegian Sea to drill wildcat well 6507/2-5 S, where Equinor is operator.
