7120/9-2

General

Wildcat well 7120/9-2 is located in The Hammerfest Basin, west of the Albatross discovery, later included in the Snøhvit Discovery. The structure comprised a dome like feature transected by a few major N-S, and E-W oriented faults. The 7120/9-2 well was drilled in a crestal position on this structure and planned total depth was 5500 m in rocks of Permian/Carboniferous age. The objective of well 7120/9-2 was to test Permian reservoirs confined by Permian Marker III (4810 m ±150 m), Permian Marker II (4745 m ±50 m), and Permian Marker I (4620 m ±150 m) for hydrocarbons.

Operations and results

Well 7120/9-2 was spudded with the semi-submersible rig Treasure Scout on18 April 1984 and drilled to a total depth of 5072 m in limestones, siltstones and cherts the Permian Røye Formation. The well was drilled with Bentonite and seawater to 381 m, with KCl/Polymer mud from 381 m to 1165 m, with Lignosulfonate /Polymer mud from 3900 m to 4270 m, and with Gel/Lignosulfonate mud from 4270 m to TD. A 17 1/2" pilot hole was drilled to 1165 m, before underreaming to 26" hole. The underreamer was lost in the hole and the well was sidetracked at 1070 m. While running the 20" casing, it parted but was recovered. Before drilling the 12 1/4" hole section two cement squeeze jobs were performed due to a low leak off test. Due to lost circulation the 9 5/8" casing was set at 4270 m. Before drilling the 8 3/8" hole section a cement squeeze job was performed due to a low leak off test. Due to lost circulation the 7" liner was set at 4791 m. Two cement squeeze jobs were performed. At 5072 m lost circulation problems occurred, the well was logged and plugged back and terminated earlier than prognosed.

Some of the Jurassic sandstone intervals encountered between 1970 m and 2290 m were gas bearing, with structural closure at the point where the well bore penetrated the formation. The intervals were subdivided into thr