The Cygnus Field, Blocks 44/11a and 44/12a, UK North Sea

Abstract

The Cygnus Field is located in Blocks 44/11a and 44/12a of the UK Southern North Sea. The field was first discovered in 1988 as a tight lower Leman Sandstone Formation gas discovery by well 44/12- 1. After the licences had sat idle for several years, GDF Britain (now Neptune E&P UK Ltd) appraised the field from 2006 to 2010. During the appraisal phase, the lower Leman Sandstone was found to be of better quality than first discovered and the gas-bearing lower Ketch Member reservoir was also encountered. The field development was sanctioned in 2012.The field has been developed from two wellhead platforms targeting Leman Sandstone and Ketch Member reservoirs. Five main fault blocks have been developed, with two wells in each fault block planned in the field development plan. The wells are long horizontal wells completed with stand-alone sand screens. At the time of writing, the production plateau is 320 MMscfgd (266 MMscfgd when third-party constraints apply), producing from nine wells with the final production well to be drilled.

Use of exploration methods to repurpose and extend the life of a super basin as a carbon storage hub for the energy transition

“…Thicknesses of the Ketch Formation range from approximately 100 m to approximately 400 m (Conway and Valvatne, 2003;Moscariello, 2003;O'Mara et al, 2003a;Dredge and Marsden, 2020;Huis in't Veld et al, 2020;Moscariello and Goffey, 2020), and it shows a general southwesterly thickening with the thickest intervals preserved in the Schooner and Ketch fields. Detailed field studies have demonstrated that the sandstones were deposited by a northeast-to-southwest-flowing, braided fluvialdeltaic system draining emergent areas of the Mid North Sea high and Rinkobing-Fyn high (Morton et al, 2005).…”

“…A major desert lake (salina) developed in more northern areas with dry and wet continental sandy sabkha deposits characterizing the transition to form a waste zone (Figures 23,25). Recent exploration success (e.g., at Cygnus) has shown that sandstone deposition also characterizes the Rotliegend on the Mid North Sea high flank to create a coarse clastic fringe along the northern margin of the basin (Catto et al, 2018;Dredge and Marsden, 2020).…”