Equinor has been unsuccessful with its Stalull exploration well, drilled using the âDeepsea Bergenâ S/S in PL 630. 35/10-4 S penetrated a 210 m section of the Brent Group. Of this 40 m comprised sandstone reservoir rocks, however, reservoir quality was poor to moderate. A 140 m section of the Cook Formation was encountered, of which 75 m were effective reservoir rocks. Reservoir quality was moderate to good. In the Heather Formation approximately 10 m of thin sandstone layers with poor reservoir quality were encountered. The well also encountered a 17 m section of good reservoir quality sands in the Paleocene. The well was drilled to TD at 4,010 m in the Amundsen Formation and on 15 October 2018 sidetrack 35/10-4 A was kicked-off. This well targeted the Upper Jurassic, Oxfordian Gnomoria prospect. A section of poor reservoir quality sandstone layers were encountered in the Heather Formation totaling 122 m. Oil was proven although no OWC was encountered. Estimated recoverable reserves are 1.25 â 7.5 MMbo. 35/10-4 A was drilled to TD at at 3,946 m (3,430 m TVD) in the Heather Formation. The well was abandoned on 12 November 2018.   The initial drilling plan stated that the 35/10-4 A well would also be drilled on Stalull, downdip, (if the main wellbore was a success) and would target the Oseberg Formation with a planned TD of 4,490 m (4,184 m TVD), and that 35/10-4 B was the sidetrack designated to target Gnomoria.   35/10-4 S lies immediately west of the small Syrah oil discovery which was made by Wintershall in 2015 with exploration well 35/11-18. A 275 m thick Middle Jurassic Brent Group section was present with light oil columns in the Tarbert Formaton (11 m) and the Oseberg Formation (3 m â the Oseberg Formation is the basal part of the Brent Group in this area of Norway). There was also an 8 m hydrocarbon column in the Upper Jurassic, Oxfordian Heather Formation. Sidetrack 35/11-18 A was drilled 450 m south of the discovery and proved gas and oil in two Heather Formation sandstones (33 m and 24 m thick). Oil was also present throughout the Brent Group (270 m thick) and there was a 46 m light oil column in the Cook Formation. The Cook and Oseberg formations were tested and exhibited good flow properties. Recoverable reserves were estimated at 6-19 MMbo.   Equinor Energy AS operates PL 630 with a 60% interest. It is partnered by Wellesley Petroleum AS which holds the remaining 40%.
Norway (Oseberg Fault Block (Horda Platform)) Oseberg