15/12-23 A

General

Well 15/12-23 A is a geological sidetrack to well 15/12-23, which proved oil in the Middle Jurassic Sleipner Formation and the Late Triassic Skagerrak Formation. It was drilled to appraise the Jurassic and Triassic potential in the western flank of the Grevling prospect in the Southern Viking Graben in the North Sea.

Operations and results

Well 15/12-23 A was drilled with the semi-submersible installation Transocean Winner. It was kicked off at 1191 m, below the 13 3/8" casing shoe in 15/12-23, and drilled to TD at 4772 m (3327 m) in the Middle Jurassic Sleipner Formation. The well was drilled with ENVIROMUL oil based mud from kick-off to TD.

The Hugin Formation was encountered at 4603 m (3220 m TVD). It had very good reservoir conditions and oil shows, but was water filled. The Sleipner Formation was encountered at 4632 m (3242 m TVD) and the upper section down to 4699 m consisted dominantly of coal beds and interbedded sandstones, which were difficult to interpret from logs. Some interbedded sandstones had shows and some had no shows. From 4699 m the Sleipner Formation was oil-bearing down to a probable OWC around 4725 m (3315 m TVD). Shows were recorded down to 4735 m.

Three cores were cut, core 1 from 4612 to 4664 m, core 2 from 4664 to 4701 m and core 3 from 4701.2 to 4741 m, giving a total of 129 m of core.

No wire line logs were run hence no down-hole fluid samples were taken.

The well was permanently abandoned on 18 July 2010 as an oil appraisal.

Testing

<p class=M