30/9-21 A

General

Well 30/9-21 A was drilled in the Oseberg Field area in the northern Viking Graben. The objectives of the sidetrack was to evaluate play of the Late Jurassic Draupne and Heather sands (Richards prospect) and to collect enough data to be able to make development plans based on this data.

Operations and results

Wildcat well 30/9-21 A was drilled with the semi-submersible installation Transocean Winner. It was sidetracked from 30/9-21 S at 1233 m on 4 May 2008 and drilled to a total depth of 4086 m in the Early Jurassic Drake Formation. On the last wire line run (VSI-VSP) at final TD the tool string became stuck after logging the second station at 4020 m. The run was aborted, the cable was disconnected and pulled out of the hole and the tool string was left in the hole. No fishing attempts were made. The well was drilled with Paratech oil based mud from kick-off to TD. Chromatographic analyses of mud filtrate from the well (PVT report) indicated that the base oil consist of mainly n-alkanes in the range C13 to C20.

The well penetrated rocks of Tertiary, Cretaceous and Jurassic age. The well penetrated the target Lower Draupne at 3616.8 m, on prognosis and Upper Heather at 3670 m, 36 m deeper than prognosis, hitting poor quality turbidite sandstones with weak oil shows. Wire line logs proved the well to be water bearing.

Three cores were cut in the Draupne and Heather Formation in the interval from 3650 m to 3825 m driller's depth. For all cores a shift of - 4 m relative to drillers depth was necessary to get a match with the loggers depth. No wire line fluid samples were taken, only MDT pressure points.

The well was perman