34/10-48 A

General

Well 34/10-48 A was drilled on the Gullfaks Field in the Northern North Sea, from the Gullfaks C platform. The main exploration objective of the well was to test the hydrocarbon potential of the Brent Group in the Topas prospect, same as for the primary well 34/1-48 S. The well should be completed as a producer. The preliminary results of the well 34/10-48 S indicated however that the well path had penetrated low on the Topas structure, which was not ideal for production. It was therefore decided to drill the sidetrack 34/10-48 A and aim as high on the re-interpreted structure as possible.

Operations and results

Sidetrack well 34/10-48 A was spudded from a preset 32" conductor at slot 29 on the Gullfaks C platform on 17 March 2004. It was kicked off from 48 S at 5120 m and inclination was increased to 103 deg in order to avoid the OWC found in 48 S. The well path was lifted approximately 100 m TVD on the most compared to 48 S. The well was drilled with Versavert oil based mud from kick-off to TD

The well 34/10-48 A drilled through hydrocarbon filled sands of both Tarbert and Ness Formations before entering the Late Jurassic sequence. The well bore was abandoned at a TD of 6221 m /2870 m TVD in the Viking Group before re-entering the Topas structure in the north. This was due to severe hole problems after a bit trip to change a failed drilling assembly. An open hole sidetrack (34/10-48 AT2) was performed with kick-off in the Ness Formation at 5608 m. This track was drilled to final TD at 5878 m / 2846 m TVD RKB in the Late Jurassic sequence. The last 50 m of well 34/10-

48 AT2 drilled through intra Heather sandstones with apparently good reservoir quality and hydrocarbon saturation.

No cores were cut and no fluid samples were collected in 34/10-48 A.

The final sidetrack, 34/10-48 AT2 was completed with one manual sleeve in Lunde, three diacs sleeves in Brent and finally another manual sleev