6305/9-2

General

The exploration well 6305/9-2 is located in the northern part of block 6305/9, 25 km east of the Ormen Lange field. The main objective was to test the presence of hydrocarbons in the Dovregubben prospect, in the Palaeocene Tang Formation channel sandstones. Secondary prospects were identified in the Paleocene Egga Formation and in the Late Cretaceous Springar Formation.

Operations and results

Wildcat well 6305/9-2 was spudded with the semi-submersible installation Aker Barents on 26 December 2010 and drilled to TD at 3075 m in the Late Cretaceous Springar Formation. After the 36" section a 9 7/8" pilot hole was drilled from 381 m to 496 m using seawater and hi-vis pills to check for shallow gas. Shallow gas was detected in a sandy interval from 484 m to 486 m. The pilot was cemented and opened up/drilled with 26" BHA down to 477 m where 20" casing was set, shallower than planned due to the shallow gas. While drilling the succeeding 17 1/2" section gas peaks (drilled gas) were recorded at 485 m (2.8%), 577 m (2.7%) and 636 m (2.4%) in sandy intervals. The well took significantly longer time than planned. The main causes for this was hole problems (134.5 hrs) and WOW (472.5 hrs, of which 386.5 hrs occurred after pulling riser and BOP, before final anchor handling and abandonment). The well was drilled with seawater and bentonite down to 477 m, with seawater and polymer mud from 477 m to 671 m, and with Glydril mud (3.5 - 5.1% glycol) from 671 m to TD.

The geology and the depth prognosis of the well came in very much as prognosed. The Tang Formation sandstones were thinner than expected, and with poorer reservoir quality. The secondary targets contained Egga Formation reservoir and thin Springar Formati