25/10-10

General

Well 25/10-10 was drilled just west of the Balder Field complex on the Utsira High in the North Sea. The well was planned to test the hydrocarbon potential of the Balder Triassic prospect with reservoir of Early Triassic age in the Smith Bank Formation as the primary target.

Operations and results

Wildcat well 25/10-10 was spudded with the semi-submersible installation Aker Barents on 1 March 2010 and drilled to TD at 2513 m in the Late Permian Zechstein Group. The well was drilled with a 9 7/8" pilot hole prior to the 17 1/2" from 234 m to 1102 m to check for shallow gas. No shallow gas was seen. The well was drilled with seawater and hi-vis sweeps down to 234 m, with pre-hydrated bentonite/CMC/Seawater from 234 m to 1102 m, and with Glydril mud containing 5.0 - 5.5 % glycol from 1102 m to TD.

The Skade Formation in the Hordaland Group and the Balder Formation in the Rogaland Group was found to be hydrocarbon bearing. The Skade Formation is 11 m thick and has a porosity ranging from 15 to 33% with an average of 17.4%. The net sand and pay interval was 2.3 m, however no shows were recorded here and it was interpreted that these hydrocarbons were severely biodegraded. The more heterogeneous hydrocarbon interval in Balder Sandstone Formation in the Upper Rogaland Group ranged from 12 to 24% with an average of 17.5%. A net pay interval of 1.7 m in a net sand interval of 5.6 m was found.

The Late Cretaceous Tor formation was found directly resting on the Early Jurassic Statfjord Formation at 2072 m. No Middle - Late Jurassic sediments were present in the well. The target Intra Triassic sandstone was encountered 77 m deep to prognosis, at 2432 m. The Intra Triassic sa