34/10-2

General

Well 34/10-2 was drilled on the "Alpha closure" in the northern North Sea, ca 8 km south of the 34/10-1 Gullfaks discovery drilled three months earlier on the "Delta structure". The primary objective of 34/10-2 well was to test sandstones of the Middle Jurassic series. The secondary objectives were sandstones of the Paleocene and Early Jurassic series.

Operations and results

Wildcat well 34/10-2 was spudded with the semi-submersible installation Ross Rig on 9 September 1978 and drilled to TD at 3729 m in the Late Triassic Lunde Formation. No significant problem was encountered during drilling, but close to15 days were spent as WOW due to severe weather conditions, and final logging at TD suffered from the weather. The well was drilled with spud mud down to 517 m, with gel/lignosulphonate mud from 517 m to 1723 m, and with gel/lignosulphonate/"ADF Chrome Lignite" mud from 1723 m to TD.

Well 34/10-2 proved the presence of gas in sandstones of Middle Jurassic Brent Group and oil in sandstones of the Early Jurassic Statfjord Formation. The Brent Group was hydrocarbon bearing all through from top at 2944 m down to top Dunlin Group (Drake Formation) at 3124 m. A total of 109 m was net pay sandstone with average porosity 20.8% and average water saturation 13.8%. The gas/oil/water contact was not seen. The Statfjord Formation was oil bearing from 3325 m down to ca 3390 m based on the well logs. It contained 31.75 m of net pay oil bearing sandstone with average porosity 15.9% and average water saturation 21.6%.

Shows started at 1640 m. These were described typically as gold yellow fluorescence and fast streaming milky cut on claystones with trace sands