34/7-29 S

General

Exploration well 34/7-29 S was drilled in the west central part of block 34/7 on the H-North prospect. The H-North prospect was located SSE of the Vigdis field and NE of the Statfjord East field. The main objective of well 34/7-29 S was to test a northerly extension of the oil bearing Upper Jurassic Top Draupne Sands penetrated in wells 34/7-21, 21 A, 23 S & 23 A. The well was designed to test the presence of reservoir, hydrocarbons and pressure communication with the other H-Area segments. Reservoir presence was considered the primary risk. Seismic interpretation of the reservoir interval indicated communication with the H-West area, and pressure, sample and DST data were considered important to test this interpretation. In addition the well was to test for the presence of sands and possible hydrocarbons in the Middle and Lower Draupne Formation. Secondary objectives were to test the lithology and depositional model of the Palaeocene Lista Formation and tie the Top Brent seismic marker.

Operations and results

Exploration well 34/7-29 S was spudded with the semi-submersible installation "Transocean Leader" on 4 March 1998 and drilled and cored to TD at 2927 m (2848 m TVD RKB) in the 8 1/2" hole section 30 m into the Middle Jurassic Brent Group. A 7" liner was set and cemented. The well was drilled with Sea water and bentonite sweeps down to 1211 m and with "AQUACOL D" KCl / Glycol mud from 1211 m to 2558 m, and with "ANTISOL D" PAC mud from 2558 m to TD. Due to the presence of hydrocarbons and the requirement for the rig to go on contract for Norsk Hydro, the well was suspended on 14 April 1998 as an oil discovery. The semi-submersible drilling installation "Deepsea Bergen" re-entered well 34/7-29 S R on 22 February 1999 for testing.

In the Nordland, Hordaland and Rogaland Groups the well penetrated mainly clay/claystones with some beds of sand. The Heimdal equivalent Member between 1928 -1999 m (1864