35/11-10 A

General

Well 35/11-10 A is a sidetrack to 35/11-10, located on the western edge of the Uer Terrace, ca 9 km North of the Troll Field. It was drilled as an exploration side-track to well 35/11-10 into the down-faulted F-Southwest compartment. This compartment lies to the west of the F-East structure drilled by 35/11-10 and 35/11-4. The objectives of sidetrack 35/11-10 A were to test the presence of prospective hydrocarbons in the Sognefjord and Fensfjord Formations, and in the Brent Group.

Operations and results

Appraisal well 35/11-10 A was drilled with the semi-submersible installation West Vanguard. Kick-of was at 1180 m in well 35/11-10, on 23 June 1997. The well was drilled to TD at 3259 m (2889 m TVD RKB) in the Middle Jurassic Oseberg Formation Formation. The deviation increased up to 38 deg. at 1564 m and was kept mostly within 38 to 40 deg. from there to TD. The well was not logged beyond 2761.4 m due to severe hole conditions. Some problems were encountered in cutting the 20" and 30" casing during abandonment. Otherwise no significant problem was encountered. The well was drilled with ANCO 2000 glycol mud from kick-off to TD.

Weak shows were recorded from 2105 m, in Late Cretaceous limestones of the Jorsalfare Formation, and in various lithologies through the Late Jurassic down to 3090 m at the base of the Heather Formation. Spotted, good shows were seen in the Ness Formation. All three target reservoirs proved water bearing. Only negligible, non-economic amounts of hydrocarbons may be present in a channel in the Ness Formation. The results were however not conclusive due to the lack of wire line logs and MDT pressure points over the actual interval (3091 m to 3137 m). No cores were cut and no fluid sample obtained in this bore hole.

The well was permanently abandoned on 23 June 1997 as dry appraisal well.

Testing

No drill stem test was performed.