34/10-52 A

General

Well 34/10-52 A was drilled on the 10A and 10B fault segments in the southern part of the Gullfaks Sør field, located in the northern part of the North Sea. This was the first well to be drilled on these segments, and the objective for well was to prove hydrocarbons and further production potential in the Gullfaks Sør Brent Group and to support decisions on future development in the Gullfaks Sør area.

Operations and results

Wildcat well 34/10-52 A was spudded with the semi-submersible installation Deepsea Atlantic on 18 June 2011 and drilled to TD at 3520 m (3472 m TVD) in the Early Jurassic Drake Formation. It was drilled vertical down to 2150 m, then building angle up to ca 16 deg and keeping that angle down to TD. No significant technical problem was encountered in the operations. The well was drilled with sea water and hi-vis sweeps down to 245 m, with spud mud and hi-vis sweeps from 245 m to 300 m, with Polymer WBM from 300 m to 796 m, with Glydril WBM from 796 m to 2162 m, and with Versatec OBM from 2162 m to TD.

Well 34/10-52 A penetrated an incomplete Brent Group package in the Gullfaks Sør segment 10B, parts of the Tarbert and Rannoch Formations were faulted out. BCU came in at 3228 m (3191.9 m TVD), 44 m deeper than prognosed and top Brent Group came in at 3282 m (3243.8 m TVD), 91m deeper than prognosed. Initial pore pressure was measured throughout the whole Brent Group except for a smaller interval in the Ness Formation that had approximately 20 bars lower pressure. No hydrocarbon contacts were observed in the well, only down-to situations. Gas-down-to 3287 m (3249 m TVD) and oil-down-to 3314.5 m (3275 m TVD) were observed in Tarbert. Gas was observed in Ness. A WUT was observed at 3324 m (3284 m TVD). No oil s