Equinor Energy AS, operator of production licence 025, has concluded the drilling of wildcat wells 15/3-12 S and 15/3-12 A in the central part of the North Sea. 

The wells were drilled about 11 kilometres southeast of Gudrun, 4 kilometres southeast of the 15/3-4 (Sigrun) oil and gas discovery and 220 kilometres west of Stavanger. The wells were drilled as sole risk wells by Equinor Energy AS and Neptune Energy Norge AS.

The primary and secondary exploration targets for wildcat well 15/3-12 S were to prove petroleum in Middle and Upper Jurassic reservoir rocks (the Hugin and Draupne Formations), respectively.

The well encountered three separate oil-filled reservoir zones of 9, 4 and 9 metres in the Hugin Formation, which are about 100 metres thick. The reservoir zones mainly have moderate reservoir quality. The oil/water contacts were not encountered.

The exploration target for wildcat well 15/3-12 A was to prove petroleum in Upper and Middle Jurassic reservoir rocks (the Draupne and Hugin Formations), respectively. The well encountered the Draupne and Hugin Formations with respective thicknesses of about 85 and 120 metres. Both formations are water-bearing. There are indications of oil in a thin, three-metre sandstone layer in the Sleipner Formation in the Middle Jurassic. 

Preliminary estimates place the size of the oil discovery between 1.0 and 2.7 million standard cubic metres (Sm3) of recoverable oil. Development of the discovery as a tie-in to the Gudrun field will be considered. 

No formation tests were performed, but extensive volumes of data have been collected and samples have been taken.

These are the 10th and 11th exploration wells in production licence 025. The licence was awarded in licensing round 2-A in 1969.

Wells 15/3-12 S and 15/3-12 A were drilled to respective vertical depths of 3652 and 3796 metres below sea level, and respective measured depths of 3771 and 3999 metres below sea level. Both wells were terminated in the Sleipner Formation in the Middle Jurassic. Water depth at the site is 109 metres. The wells have been permanently plugged and abandoned.

The wells were drilled by the West Phoenix drilling facility, which will now drill wildcat well 6507/8-10 S in production licence 889 in the Norwegian Sea, where Neptune Energy Norge AS is the operator.

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