6406/9-1

General

Well 6406/9-1 is located in the southern Haltenbanken area, offshore Mid Norway. The well was drilled near the crest of the prospect structure, a rotated fault block. The primary objective of well 6406/9-1 was to test the hydrocarbon potential in the Middle to Early Jurassic reservoirs of the Garn, Ile, Ror/Tofte and Tilje Formations, and to production test possible hydrocarbon occurrences.

Operations and results

Wildcat well 6406/9-1 was spudded with the semi-submersible installation Transocean Leader on 15 June 2004 and drilled to TD at 5080 m in Early Jurassic sediments of the Åre Formation. The well was a high temperature / high pressure well, with a formation temperature of ca 184 deg C at TD, according to DST and wire line measurements. The well was drilled with seawater and bentonite sweeps down to 1375 m, with Glydril mud from 1375 m to 2893 m, and with Paratherm oil based (paraffin base) mud from 2893 m to TD. Shallow gas was neither predicted nor encountered. Due to labour disputes and bad weather the well was not terminated until 2 June 2005.

The Jurassic Ile, Tofte, Tilje and Åre Formations were all found to be entirely gas bearing. The Garn Formation, a reservoir interval in some of the neighbouring wells, was found to be shaled out here. The presence of hydrocarbons was confirmed by RCI samples in the Ile, Tofte and Tilje. The discovery appeared to be a stacked reservoir sequence with up to 5 different compartments with small pressure differences between the formations. All reservoirs were intersected in Gas-Down-To situations. The total hydrocarbon column in-well was 492.5 m. The gas was significantly drier than expected when compared to other accumulations in the area. Reservoir quality was very variable with large sections of low/medium permeability, but also two distinct sands of exceedingly high quality.

A total of four cores were taken from the Early and Middle Jurassic intervals. The first core