25/2-15 R2

General

The well is located in the southern part of block 25/2, and was designed to recognize the petroleum potential of the so-called Jurassic Prospect 1. The main objective of the well was to explore the Middle Jurassic Vestland sandstones. An optional objective was Early Jurassic Statfjord sandstones, depending on the petroleum results at the Brent level.

Well 25/2-15 R is a re-entry of well 25/2-15, which was drilled with the semi-submersible installation West Alpha. Due to a fire on the West Alpha installation the well was temporarily abandoned on 13 January 1993, with the drill string in the hole. The 25/2-15 R re-entry retrieved the West Alpha BOP, fished out the lost drill string, performed logging, and set 9 5/8" casing. After that, the hole was again suspended and the installation used, West Vanguard, left to Dusavika for BOP change out. The purpose with the 25/2-15 R2 re-entry was to fulfil the original geological objectives.

Operations and results

Wildcat well 25/2-15 was re-entered for the second time (25/2-15 R2) with the semi-submersible installation West Vanguard on 6 March 1993 and drilled to final TD at 3942 m in the Early Jurassic Dunlin Group. No significant drilling problems were encountered in the borehole. At 3602 m, during coring, a water kick was detected. At TD a discrepancy of 8 m between driller and log depth was recorded, log depth being the deeper.

The Vestland reservoir proved to be water bearing, with residual hydrocarbon shows. Very good shows were observed in Shetland-limestones of Late Campanian - Early Maastrichtian age. However, no RFT pressure measurements/fluid samples were achieved. Both the bio- and lithostratigraphy of the formations in the lowermost part of the well, was initially indistinct. The biostratigraphy study however, made it clear that TD of the well was in a formation belonging to the Dunlin Group, of Late Pliensbachian -Middle Toarcian age. Two cores were cut in