33/9-18

General

Well 33/9-18 was drilled to a structure situated east of the Statfjord Field and south-west of the Tordis Field. The main objective of the vertical well 33/9-18 was to explore the hydrocarbon potential of possible sandstones and to test the current geological model. The secondary objective was to explore the hydrocarbon potential of a lead in the Heather Formation.

Operations and results

Exploration well 33/9-18 was spudded on 16 November 1994 with the semi-submersible installation Deepsea Bergen and drilled to TD at 3253 m in the Late Jurassic Draupne Formation. The 36" and 26" hole sections were swept with high viscosity bentonite pills. The 17 1/2" and the 12 1/4" hole sections were drilled with KCl/PAC POLYMER and KCl mud system to prevent bit balling. No shallow gas was recorded.

The well 33/9-18 had tight spots from 325 m to TD. Experienced differential sticking at 1230 m, 1650 m, 1680 m and tight hole from 1652 m to 3140 m. Bit balling occurred in 26" and 12 1/4" section. High viscosity bentonite pills were pumped to improve the flow pattern in an attempt to minimize balling problems.

From 2450 m and down to base Cretaceous at 2849 m the pore pressure increases and reaches approximately 1.54 g/cc which is the maximum pore pressure in the well. The rest of the well has been interpreted as being drilled into the Viking Group, which here contain large slump/slide blocks of Statfjord Formation, Dunlin Group and Brent Group. Within those blocks, the pore pressure seem to be somewhat higher than original pressures in the Statfjord Field. FMT pressures gives pressures in the range of 1.47 g/cc at 3006 m and 1,5 g/cc at 3019 m. No fluid samples were collected in the well.

Two cores were cut in Draupne Formation (core no. 1 was cut in the interval 2967-2978 m and core no. 2 was cut in interval 3045-3054 m) and 1 core in Heather Formation (in the interval 3233-3242 m). No hydrocarbon shows