25/8-15 S

General

Well 25/8-15 S was drilled as a dual objective well from the Ringhorne platform. The objective was to first penetrate the Paleocene Zone II reservoir, and then to appraise the Early Jurassic Ringhorne East structure, found oil bearing in the 25/8-14 S well. At the time of drilling the well was called 25/8-C-03, since it was drilled from the Ringhorne platform and had a production well target. After completion it was decided that it would be called 25/8-15 S. The plan for this appraisal well was to take pressures in the Jurassic and to get a good seismic tie for the Jurassic below the Statfjord Formation S5 sand.

Operations and results

Well 25/8-15 S was drilled from the fixed installation Ringhorne platform, slot AD, C-03. It was spudded on July 13 2004 and drilled to 4804 m (2038 m TVD RKB) in the Early Jurassic Statfjord Formation where drilling problems occurred. The end result was that the total bottom hole assembly (BHA), with Gamma Ray, Resistivity, Density, Neutron, Sonic and Tes Trak, was left in hole at 2972 m, before any pressure data or real time Sonic data was acquired. After nine days of working stuck BHA, the Pipeseis Chekshot was run to TD, before the well was plugged back. The well was drilled with seawater down to 312 m, with NaCl/KCl polymer mud from 312 m to 1310 m, and with Versavert oil based mud from 1310 m to TD.

Well 25/8-15 S found Zone II to be thin and below the Paleocene oil/water contact (OWC), so no development wells were prepared for as originally planned. The well found a massive, 14.3 m net pay Jurassic Statfjord sandstone at 4698 m (1985.1 m TVD RKB) The sandstone was oil bearing all through, with no defined OWC. The S5 sand was not penetrated. No cores were cut and no fluid samples taken in the well.

The well was permanently abandoned on 7 August 2004 as an oil appraisal.

Testing

No drill stem test was performed.