34/7-2

General

Well 34/7-2 was drilled just north of the Tordis Øst discovery in the northern North Sea. The main objectives were to test for hydrocarbons in the Jurassic Statfjord Formation and in the Triassic Lunde Formation.

Operations and results

Wildcat well 34/7-2 was spudded with the semi-submersible installation Treasure Saga on 2 September 1984 and drilled to TD at 2475 m in the Late Triassic Lunde Formation. A total of 83 hours rig time was NPT due to repairs resulting from a failed RIH with the 26" bit after underreaming to 816 m, and a leak in the acoustic system discovered after setting the 9 5/8" casing at 2031 m. The well was drilled with seawater and hi-vis pills down to 848 m, with KCl/polymer mud from 848 m to 2042 m, and with lignosulfonate mud from 2042 m to TD. No shallow gas was encountered.

Except for the sandy Utsira Formation and two sandstone units in the Hordaland Group (in the order of 40 - 50 m each) the well proved mainly claystones down to the Statfjord Formation at 2152 m. At BCU (2085 m) there was a major hiatus from Pliensbachian to Campanian. The Lunde Formation was encountered at 2271 m. The gross thickness of the Statfjord in this well is 119 m with 43.5 m of net sand. The well drilled some 204 m into the Lunde Formation, which in the upper part proved a siltstone sequence with minor sandstone and claystone, while the lowermost 117 m proved a sequence of sandstones alternating with claystones. Of this sequence some 41.3 m could be considered as net. No live hydrocarbons were encountered by the well. Residual oil was found in base Amundsen - top Statfjord Formations, however, cores showed low porosity and essentially no net sand. Ex