34/7-10

General

Well 34/7-10 was drilled on the southern end of the Snorre Field. The primary purpose of well 34/7-10 was to prove Statfjord Group reserves in the south-east Snorre. Further objectives were to test the Statfjord Group thickness and sand distribution, to test the extent and quality of the middle Statfjord member and to establish a Statfjord Group OWC and reservoir parameters of the Statfjord Group and underlying upper Lunde Formation.

Operations and results

Appraisal well 34/7-10 was spudded with the semi-submersible installation Treasure Saga on 26 August 1986 and drilled to TD at 3000 m in the Late Triassic Lunde Formation. Drilling proceeded without significant problems. The well was drilled with spud mud down to 430 m, with gel mud from 430 m to 918 m, with gypsum/polymer mud from 918 m to 2413 m, and with KCl mud from 2413 m to TD.

Apart from the sandy Utsira Formation of Late Miocene age, a Late Oligocene (1314 - 1324 m) and a Late Eocene (1377 - 1387 m) sandstone unit within the Hordaland Group, the upper section down to Jurassic proved mainly claystones. The Jurassic consists of a silty Dunlin Group and a sandy Statfjord Formation. The Triassic consists of claystones with minor sandstones in the upper part and alternating sandstones/ claystones from 2800 m and down to TD. First traces of shows were seen at 2120 m in silty laminas of the Shetland Group. These are described as weak dark yellow fluorescence with slowly streaming light yellow cut. From 2250 m and down to top Statfjord Group oil reservoir at 2531.5 m silt and sandstone show weak to moderate dull yellow to bright yellow fluorescence and slowly streaming blue white to milky white cut. The residue is yellow to light brown in colour. Below the OWC at 2621 m sh