6507/11-7

General

Wildcat well 6507/11-7 is located in the Grinda Graben, a major structural element in PL263 on the Halten Terrace off shore mid Norway. The primary objective of the well 6507/11-7 was to prove commercial hydrocarbon resources in the Late Cretaceous Zita prospect. The Zita prospect is a Lysing Formation reservoir in a stratigraphic trap model. A secondary objective of the well was to prove commercial hydrocarbon resources within the Late Cretaceous Zit-B prospect. The Zit-B prospect is an Upper Lange Fm reservoir in a stratigraphic trap model.

Operations and results

Well 6507/11-7was spudded with the semi-submersible installation Transocean Winner on 13 December 2006 and drilled to TD at 2950 m in Early Cretaceous (Late Albian) sediments of the Lange Formation. Spudding was made difficult by large boulders and unacceptable inclination in the first top hole led to a re-spud ca 15 m northwest of the original location. Otherwise operations proceeded without significant problems. The well was drilled with spud mud down to 535 m, with Polymer/KCl brine mud from 535 m to 2484 m, and with Ultradril mud from 2484 m to TD. The Ultra drill mud contains Ultrafree NS, which consists of C14-C16 linear alpha olefins.

No hydrocarbons were proven in the well. Calcite cemented sand layers of Coniacian toTuronian age (Lysing Formation) were encountered in a 39 m thick interval (2777 - 2817 m). The stacked sand layers had very low porosities and permeability values, and was water wet. Formation pressure measurements showed higher pressure in the Lysing Formation sands in well 6507/11-7, than in the comparable down-dip Smørbukk S discovery in the Lysing Formation This indicated that the encountered sands were not in direct pressure communication with the Lysing Formation sands in the region. Post-well organic geochemical analyses of mud gas, cuttings and SWC's confirmed a dry well with no indication of migrated hydrocarbons.

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