Gas/condensate and oil discovery west of the Troll field in the North Sea
19/07/2023 Wellesley Petroleum AS, operator of production licence 1148, has concluded the drilling of wildcat wells 35/10-10 S and 35/10-10 A.
The wells were drilled about 25 km northwest of the Troll field and 150 km northwest of Bergen.
The primary exploration target for well 35/10-10 S was to prove petroleum in Middle Jurassic reservoir rocks in the Etive and Oseberg formations in the Brent Group. The secondary exploration target for well 35/10-10 S was to prove petroleum in the Early Jurassic Cook Formation.
The objective of appraisal well 35/10-10 A was to encounter the petroleum-water contact in a lower position on the structure, and to collect liquid samples from the aquifer.
Well 35/10-10 S encountered a 210-metre gas-condensate column in the Ness, Etive and Oseberg formations, of which a total of 90 metres was sandstone reservoir with poor to moderate reservoir quality. In the Cook Formation, the well encountered a 70-metre gas-condensate column, of which a total of 23 metres was sandstone reservoir with poor reservoir quality. A 13-metre oil column was also encountered in the Early Jurassic Amundsen Formation in the Dunlin Group, whereof a total of 13 metres was sandstone reservoir with poor reservoir quality.
Well 35/10-10 A was drilled lower on the structure, 900 metres west of the main well and encountered a 240-metre gas-condensate column in the Ness, Etive, Oseberg and Cook formations, whereof 50 metres was sandstone reservoir with poor to moderate reservoir quality. Water was encountered in the Cook Formation from a vertical depth of 4158 metres below sea level.
Preliminary estimates indicate the size of the discovery is between 9 and 46 million standard cubic metres (Sm3) of recoverable oil equivalent. The licensees will initiate early-phase development studies, and are considering additional appraisal wells in the discovery.
Well 35/10-10 S was drilled to a vertical depth of 4030 metres below sea level, and was terminated in the Amundsen Formation in the Early Jurassic. Extensive data acquisition and sampling have been carried out.
Well 35/10-10 A was drilled to a vertical depth of 4212 metres below sea level, and was terminated in the Cook Formation in the Early Jurassic.
Water depth at the site is 360 metres. The wells have been permanently plugged and abandoned.
The wells were drilled by the Deepsea Yantai drilling facility, which will now drill wildcat well 25/7-11 S in production licence 984 in the North Sea, where DNO Norge AS is the operator.