Equinor Energy AS encountered oil and gas in wells drilled on Gudrun field in the North Sea. Preliminary estimates place the size of the discovery at 0.1-1.2 million std cu m of recoverable oil equivalent in the intra-Draupne formation, and 0.4-1.3 million std cu m of recoverable oil equivalent in the Hugin formation, the Norwegian Offshore Directorate (NOD) said in a release Sept. 17. The operator and license partners will assess the results considering other prospectivity in the area.
Drilling operations, geological detail
Wells 15/3-13 S and 15/3-13 A, the 13th and 14th wells drilled in production license (PL) 025, were drilled by the Deepsea Stavanger in 110 m of water. The primary exploration target was to prove petroleum in Late Jurassic reservoir rocks in the intra-Draupne formation, as well as Middle Jurassic reservoir rocks in the Hugin formation. The secondary target was to prove reservoir in Early Cretaceous reservoir rocks in the Rødby formation, NOD said.
Well 15/3-13 S was drilled to respective measured and vertical depths of 4,826 m and 4,740 m subsea. Well 15/3-13 A was drilled to respective measured and vertical depths of 4,900 m and 4,814 m subsea. Both wells were terminated in the Sleipner formation in the Middle Jurassic.
Well 15/3-13 S encountered thin oil-bearing sandstone layers in the intra-Draupne formation. The oil-water contact was not encountered. In the Hugin formation, the well encountered a total of 92 m of sandstone with poor reservoir properties. Gas was encountered in two intervals, with respective thicknesses of 8 m and 7 m. The gas-water contact was not encountered.
Sidetrack 15/3-13 A was drilled with the objective of delineating the discovery. The well encountered oil in an 85-m thick interval in the intra-Draupne formation, a total of 13 m of which were intermittent sandstone layers with moderate reservoir quality. The oil-water contact was proven 4,328 m subsea. The well also proved about 100 m of sandstone with poor reservoir properties in the Hugin formation. The entire interval was aquiferous, and no gas-water contact was proven.
No reservoir was encountered in the secondary exploration target, the Rødby formation in the Lower Cretaceous.
The wells were not formation-tested, but extensive data acquisition and sampling were carried out. The wells have been plugged.
Equinor is operator at PL 025 (36%) with partners Vår Energi ASA (25%), OMV (Norge) AS (24%), and Repsol Norge AS (15%).
