2/8-14

General

Well 2/8-14 was drilled on a complexly faulted anticline situated below the western flank of the Valhall Field (designated as the West Valhall prospect) in the southern North Sea. The primary objective was to test a late Jurassic "wedge" sandstone. The secondary objective was Late Jurassic, Volgian age, sandstones. The well would also determine reservoir quality of the Shetland Group chalk sequences. The planned total depth of the well was 5622 m.

Operations and results

Wildcat well 2/8-14 was spudded with the semi-submersible installation West Vanguard on 14 August 1990. No shallow gas zones were penetrated in the well. The well penetrated high pore pressures at 3176 m in the Lower Cretaceous that required plugging back the well and setting an 11 3/4" liner. High pore pressures were again penetrated at 4274 m in the Late Jurassic. Due to well control considerations, the hole was plugged back and sidetracked below approximately 3797 m before setting a 7" liner at 4202 m. Further down high pore pressures again forced a premature end to the well with TD at 4397 m in the Late Jurassic (Late Kimmeridgian) Farsund Formation. The well was drilled with seawater and pre-hydrated bentonite down to 952 m, with KCl/PHPA/Polydrill mud from 952 m to 2560 m, with AncoTemp Polydrill/Ancoresin PHPA from 2560 m to 3855 m, and with AncoTemp Polydrill/Hostadrill PHPA mud from 3855 m to TD.

Top Shetland Group Chalk (Tor Formation) was encountered at 2614 m with a 73% mud gas peak and good oil shows. The Tor Formation was 3 m thick and the underlying Hod Formation was 225 m thick. The pressures in the Tor and in the Hod chalk formations were depleted due to production from the Valhall Field as expected. Top Tyne Group, Mandal