15/12-19

General

The Pi North well 15/12-19 was drilled on the northern lobe of the Maureen Terrace in the North Sea. The prospect is adjacent to the UK Armada complex of Fields (Fleming, Drake and Hawkins) and the Seymour Fields to the West and the Varg and Rev Fields to the North. The main objective of the well was to test the hydrocarbon potential in Sleipner/Skagerrak sandstone formations in the Pi North structure.

Operations and results

Well was spudded with the jack-up installation Mærsk Guardian on18 February 2008 and drilled to TD at 3212 m in Triassic rocks of the Skagerrak Formation. A 9 7/8" shallow gas pilot hole was drilled from TD in the 36" section at 203.5 m to 672 m. No shallow gas was seen. No significant problem was encountered in the operations. The well was drilled with sea water and pre-hydrated bentonite down to 672 m, with Aquadrill mud from 672 m to 1364 m, and with Carbo SEA oil based mud from 1364 m to TD.

Top Jurassic was encountered at 2969 m and consisted of only 4 m Draupne Formation directly overlying the Triassic Skagerrak Formation. No sediments of the Jurassic Sleipner Formation were encountered. The Skagerrak Formation was hydrocarbon bearing. The sandstones had an average porosity of 17% net when using an 11.8% cut off in the oil case and 8.1% in the gas case. The reservoir system was complex with an upper reservoir with gas down to 2986.8 m (13.8 m TVD gross gas column, 9.21m net pay) and an underlying oil column of 35.7 m TVD gross (13.11m net pay). A lower reservoir with a 16.5 m TVD gross oil-leg (3.81 m net pay) was encountered at 3044.5 m. The two oil zones were separated by a 22 m thick zone of movable water (confirmed by RCI water samples). Pressure data in the different reservoir zones ind