6507/5-6 S

General

Well 6507/5-6 S was drilled from the Skarv A template on the Revfall Fault Complex in the Norwegian Sea. The objective of the well was to prove gas in Late Cretaceous reservoir rocks (the Lysing formation) in the Snadd North prospect. It was drilled primarily for data acquisition to identify the presence and producability of the Lysing reservoir, with the well path planned for optimal data recovery, but the well was also planned to be used as a producer.

Operations and results

Exploration well 6507/5-6 S was spudded with the semi-submersible installation Borgny Dolphin on 12 January 2010. The well was drilled as the fourth well in the batch drilling operations for the 17 1/2" and 12 1/4" sections on the Skarv A template. Initially the well was drilled to 4454 m. Then, due to hole instability and operational problems, the well was plugged back and sidetracked from 2346.4 m after a core was taken in the reservoir. Reservoir logs are therefore primarily taken in the sidetrack T2. Final TD was reached at 4991 m (2906.7 m TVD) in Late Turonian age claystone in the Lange Formation. The well was drilled with seawater and hi-vis pills down to 1122 m and with Carbosea oil based mud from 1129 m to TD in both the main and sidetrack well bores.

The Lysing Formation was encountered at 4676 m ( 2798 m TVD). Good quality hydrocarbon-bearing sandstones were discovered. A total thickness of 32 m TVD of Lysing sandstone was drilled, with net/gross of 0.88 and average effective porosity of 0.21. The sandstones in the core were of mixed quality, predominantly medium-fine grained and hydrocarbon-stained. The reservoir was hydrocarbon bearing throughout. No oil shows w