2/12-1

General

Well 2/12-1 is located in the Feda Graben n the southern North Sea, ca 1.5 m north of the Danish/Norwegian border. The main objective of the well was to prove the extension of the Danish "Gert" discovery into block 2/12. The primary target was Middle Jurassic sandstones, prognosed at 4826 m. Possible secondary targets were Early Jurassic and Triassic sandstones. Structural closure was not defined at Top Shetland or Base Cretaceous levels, but minor stratigraphic trapping was considered possible in this area. Prognosed TD was 5125 m.

Operations and results

Wildcat well 2/12-1 was spudded with the semi-submersible installation Treasure Scout on 14 October 1986 and drilled to TD at 4795 m in volcanic breccia of the Early Permian Rotliegend Group. Drilling proceeded without significant problems down to 3970 m where gas problems were experienced. The hole was cleaned up, and dual induction/sonic log was run. Due to increasing gas recordings 9 5/8" casing was set at 3978 m. The remaining logging program in this section was therefore not run, and sidewall cores were not taken. At 4705 m a drill- break was experienced. The hole was circulated, tested, and drilled to 4714 m. During logging the tool got stuck and the string was cut. The fish was stuck at 3842 m, and loosening was unsuccessful. 7" liner was set at 3826 m and cemented. During circulation hydrocarbons started to flow in between 9 5/8" shoe and 7" liner. The well was closed and heavy mud was squeezed into the formation. After 3 weeks the fish was pulled out of the hole. The well was drilled with spud mud down to 1015 m, with KCl/polymer mud from 1015 m to 4050 m, and with Lignosulphonate mud from 4050 m to TD

Well 2/12-1 encountered 71 m of o