ID: 702
OBJECTID: 702
wlbNpdidWellbore: 1536
wlbName: 34/7-17 A
wlbHistory:

General

Well 34/7-17 A is a sidetrack to well 34/7-17 on the Vigdis Field on Tampen Spur in the Northern North Sea. In well 34/7-17 the primary target Brent reservoir was encountered 38 m deeper than prognosed and dry with only scattered oil shows. The 34/7-17 A sidetracked well thus aimed primarily at the Brent reservoir in an up-dip position above a possible OWC. According to prognosis Brent should be truncated in this direction. A secondary objective was to test the pressure regimes in the Jurassic sequence, including possible depletion associated with pressure communication, previously identified in the nearby Tordis Field.

Operations and results

Well 34/7-17 A was spudded with the semi-submersible installation Treasure Saga on 7 April 1991. Kick off point was at 1994 m below the 13 3/8? casing shoe in well 34/7-17, in the top of the Shetland Group. The target was located up-dip in a south-easterly direction and the sidetrack was drilled deviated from its beginning. The well was drilled without significant technical problems to TD at 2650 m (2557 m TVD) in the Middle Jurassic Etive Formation of the Brent Group. It was drilled with KCl mud from kick off to TD.

Top Brent Group, Tarbert Formation, was penetrated at 2494.5 m (2439.5 m TVD). Truncation was confirmed by the absence of the Viking Group and erosion into the top of the Brent Group. The Brent Group proved to be oil bearing only in the uppermost 6.5 m TVD with a possible OWC at 2502.5 m (2446 m TVD / 2420 m MSL TVD). Above the reservoir ditch cuttings recorded a continuous sequence with good traces of oil shows between 2235 and Top Brent Group. The interval 2310 to 2370 m also had oil staining and a strong odour of hydrocarbons. No shows were reported below 2506 m.

One core was cut in the top of the reservoir between 2597 and 2617. Totally 21 m was cut, of which 20 m was recovered.

Two RFT runs were conducted over the Brent Group. The resulting pressure
wlbHistoryDateUpdated: 2016-07-06T00:00:00