Wellesley Petroleum AS, an exploration company focused on the Norwegian Continental Shelf (NCS) has announced the successful appraisal of the Grosbeak discovery in the Northern North Sea by wells 35/11-21 S and 35/11-21 A. The wells were drilled in production licence Pl248I where Wellesley holds a 60% operated interest.
Well 35/11-21 S encountered a gross oil column of 90 metres at the target Middle Jurassic Brent Group level. Within this oil column, 45 metres comprised net reservoir with good to excellent reservoir properties. Extensive data was acquired from the reservoir interval including a successful well test which confirmed the high quality and good connectivity of the reservoir. Sidetrack well 35/11-21 A encountered 20 metres of excellent quality gas-bearing reservoir and an 8-metre oil column in the shallower Upper Jurassic Sognefjord and Fensfjord formations. The underlying Brent Group reservoir comprised a 50-metre oil column in the Ness Formation with 9 metres of sandstones lying within the oil zone. Pressure data from these sandstones indicates good connectivity to the zone tested in the 35/11-21S well.
The updated range of recoverable resources in the Grosbeak discovery is 53 to 115 million barrels of oil plus 269 to 432 billion cubic feet of gas. The 35/11-21 S and A wells have been plugged and abandoned and development studies will commence.
Chris Elliott, CEO of the Wellesley Group of companies, comments, “This is a very positive end to our operated drilling campaign in the Grosbeak area. Our pre-drill subsurface studies of Grosbeak indicated that the Brent Group sandstones were both predictable and well connected and this has been demonstrated by the appraisal wells, significantly reducing the development risk of this reservoir. The discovery of a separate, excellent quality gas reservoir in the Upper Jurassic also adds significant resources to what we expect to be a material and commercially robust future development.”
“It is particularly pleasing to have reached this point only 10 months after assuming operatorship of the PL248I licence. These wells conclude an operated summer drilling campaign of 159 days duration with almost 13,000 metres drilled in five boreholes and very extensive data collected from each of the five hydrocarbon-bearing zones encountered. Drilling efficiency has been outstanding and was undertaken with excellent focus on risk management and major accident prevention. We extend our gratitude to our licence partners, our network of suppliers and the relevant authorities for their support in the planning and delivery of this well programme,” Elliott adds.