The well was drilled about 10 km northwest of the Balder field in the central part of the North Sea, and 200 km west of Stavanger.
The primary exploration target for the well was to prove petroleum in Lower Jurassic and Upper Triassic reservoir rocks (the Nansen, Eiriksson and Skagerrak Formations). The secondary exploration target was to prove petroleum in Middle Jurassic reservoir rocks (the Hugin and Sleipner Formations).
In the primary exploration target, the well encountered several oil and gas-bearing intervals with independent columns. In the Nansen Formation there is a total of 28 m of sandstone with good reservoir quality, of which 5 metres are oil-bearing.
The Eiriksson Formation has a total of 11 m of sandstone with moderate reservoir quality, of which 6 m are oil and gas-bearing. In the Skagerrak Formation there is a total of 13 m of sandstone with moderate reservoir quality, of which 8 m are gas-bearing.
In the secondary exploration target, three thin gas-bearing sandstone layers totalling 3 m with moderate reservoir properties were encountered in the Sleipner Formation. In the Hugin Formation, sandstone layers were encountered with moderate reservoir quality and a total thickness of 25 m. The Hugin Formation is water-bearing.
Preliminary estimates place the size of the discovery at between 1 and 5 million m3 of recoverable oil equivalent. The licensees will assess the well results with a view to further exploration in the licence.
The well was not formation-tested, but extensive data acquisition and sampling have been carried out.
25/7-8 S was drilled to respective measured and vertical depths of 3225 and 3188 m below sea level and the well was terminated in the Skagerrak Formation in the Upper Triassic. Water depth at the site is 126 m. This is the first exploration well in production licence 917. The licence was awarded in APA 2017.
Well 25/7-8 S was drilled by the Leiv Eiriksson drilling facility, which will continue drilling wildcat well 25/7-9 S in production licence 917, where ConocoPhillips Skandinavia AS is the operator.
Read the article online at: https://www.oilfieldtechnology.com/exploration/14012020/conocophillips-makes-oil-and-gas-discovery-in-north-sea/