6406/2-2

General

Well 6406/2-2 was drilled on the B structure (Lavrans discovery) in the eastern part of the block, south of an east-west trending cross fault. The discovery well 6406/2-1 had previously been drilled on the northern segment of the B structure. The cross fault was suspected to act as a pressure barrier between the two segments, causing variation in fluid types. The main objective of well 6406/2-2 was to prove hydrocarbons and verify fluid contacts in the southern segment, which seemed to differ from the northern segment in both the nature and intensity of the seismic amplitudes. An additional objective was to investigate any differences in reservoir development between the two segments.

Operations and results

Appraisal well 6406/2-2 was spudded 12 December 1995 with the semi-submersible installation "Ross Rig" and TD was reached at 5367 m (5351 mTVD) 12 February 1996 in the Åre Formation. The well was drilled water based with bentonite down to 1272 m, with KCl and glycol (ANCO 208) from 1272 to 2858 m, and with oil-based mud from 2858 m to TD. The formation tops were drilled in accordance with the prognosis, and the lithologies drilled were largely similar to those reported from 6406/2-1. The Jurassic succession was encountered 5-100 m deeper than in well 6406/2-1, due to the lower structural position of well 6406/2-2. As in well 6406/2-1, well 6406/2-2 proved the presence of thick reservoir sandstones in the Garn, Ile, Tofte and Tilje Formations. In addition, an 8 m thick sand was drilled in the lower part of the Ror Formation. The reservoir quality showed large variations, with generally poor porosity in the Garn Formation, good porosity in parts of the Ile Formation, generally good porosity in the Tofte Formation, and zones with good porosity especially in the lower part of the Tilje Formation. Other parts of the Ile and Tilje Formations, as well as the sandstone beds in the upper part of the Åre Formation, were tight as a