34/8-3

General

Well 34/8-3 was drilled on the A-structure on the Visund Field. This is a NNE-SSW oriented elongated fault block with the Pre-Cretaceous strata dipping towards WNW. The A-Central fault divides the A-structure into the A-North and A-South compartments. The primary objectives of the well were to test the hydrocarbon potential of the Brent Group on the A-North compartment. Planned TD was 50 m into the Statfjord Formation.

Operations and results

Wildcat well 34/8-3 was spudded with the semi-submersible installation Polar Pioneer on 14 July 1988 and drilled to TD at 3328 m (3320 m TVD) in the Early Jurassic Statfjord Formation. There were no problems with shallow gas. 9 5/8" casing was set at 2597 m instead of 2800 m due to higher pressure than prognosed in formation of Cretaceous age. Below 2600 m the well started to build some angle, up to 9.6 deg at the most. This resulted in 8 meter discrepancy between measured depth and vertical depth towards TD. The well was drilled with seawater and hi-vis pills down to 1302 m and with KCl/polymer mud from 1302 m to TD.

Oil shows were recorded in thin sandstone stringers in the Kyrre Formation between 2364 m and 2555 m. The Brent Group was encountered at 2837 m. It contained a 90 m gas column and a 13 m oil column. The gas/oil contact was at 2929 m. The oil/water contact could not be established, but DST 1 produced clean oil from the interval 2935 to 2947 m. Oil shows were recorded on sandstone on cores down to 2951 m.

Seven cores were cut in the interval 2839.0 to 2957.5 m in the Brent Group. The core depths are 1 m shallow compared to logger's depth. One RFT wire line fluid sample was taken at 2936 m. The 2 3/4 gallon chamber con