Equinor Energy AS, operator of production licence 630, has concluded the drilling of wildcat wells 35/10-4 S and 35/10-4 A. 

The wells were drilled about ten kilometres southwest of the Vega field in the northern part of the North Sea.

The primary exploration target for well 35/10-4 S was to prove petroleum in Middle and Lower Jurassic reservoir rocks (the Brent group and the Cook formation). The secondary exploration target was to prove hydrocarbons in Upper Jurassic reservoir rocks (the Heather formation, as well as to test the reservoir potential in the Palaeocene (Intra Balder sands/the Sele formation).

Well 35/10-4 S encountered the Brent group, about 210 metres thick, whereof effective reservoir rocks of 40 metres of sandstone, mainly with poor to moderate reservoir properties. The Cook formation has a thickness of about 140 metres, whereof effective reservoir rocks of 75 metres, mainly with moderate to good reservoir properties. Both of the primary targets were aquiferous.

In the secondary exploration targets, the Heather formation has thin sandstone layers totalling about ten metres with poor reservoir quality. Traces of oil were proven in one of the lower layers. In the Palaeocene, the well encountered a 17-metre thick aquiferous sand package with good reservoir properties. Data was acquired in the well.

The primary exploration target for well 35/10-4 A was to prove petroleum in reservoir rocks in the Upper Jurassic (the Heather formation). The secondary exploration target was to explore the reservoir properties in Middle Jurassic deposits from the Callovian Age.

Well 35/10-4 A encountered sandstone layers in the Heather formation totalling about 122 metres, mainly with poor reservoir quality. Oil was proven, but the oil/water contact was not encountered. Preliminary estimates show from 0.2 MSm3 to 1.2 MSm3 recoverable oil. The volume range is mainly due to uncertain reservoir quality. A preliminary assessment indicates that the discovery is not currently profitable. The well was not drilled into the secondary exploration target.

Extensive volumes of data were collected in the well.

These are the first and second exploration wells in production licence 630. The licence was awarded in APA 2011.

Well 35/10-4 S was drilled to a vertical depth of 3787 metres below the sea surface, and was terminated in the Amundsen formation in the Lower Jurassic.

Well 35/10-4 A was drilled to a vertical depth of 3427 metres below the sea surface, and was terminated in the Heather formation in the Upper Jurassic.

Water depth is 363 metres. The wells have been permanently plugged and abandoned.

The wells were drilled by the Deepsea Bergen, which then went on to drill wildcat well 6407/11-1 in the Norwegian Sea in production licence 751, where Equinor Energy AS is the operator.