6508/5-1

General

Well 6508/5-1 was drilled on a structure located in the western part of the Helgeland Basin off shore Mid Norway. The primary target was sandstone of the Early/Middle Jurassic Ile Formation. The Ti1je Formation was a secondary target in the case of a shaled out Early/Middle Jurassic sequence acting as a seal.

Operations and results

Wildcat well 6508/5-1 was spudded with the semi-submersible installation West Vanguard on 22 April 1987 and drilled to TD at 2589 m in the Triassic Red Beds. The hole was drilled without significant problems and without any signs of shallow gas. It was drilled with seawater and gel down to 961 m, and with KCl/polymer mud from 961 m to TD.

The top prospect was encountered at 1778 m and cored. The cored section exhibited excellent porosities with an average of 32% and permeabilities of generally several hundreds of mD to tens of Darcies. From petrophysical log evaluation the whole of Ile Formation had a net to gross of 64% and the same porosity average as in the cored section using a 15% porosity cut off. The Tilje Formation also possessed excellent reservoir characteristics. Reservoir characteristics remained good in the Åre Formation and Red Beds with an average of 25% porosity at around 2500 m. Unfortunately there were no signs of hydrocarbons on the logs and no shows were recorded in any part of the well, except for cut fluorescence in sidewall cores in claystones from the Spekk and upper Melke Formations. The RFT tool was run from 1786 m in the Ile Formation to 2542m in the Red Beds with 13 pressure points acquired. A clear water gradient of 1.013 g/cm3 was established. Post-well organic geochemical analyses included in the well completion reports only partly considered migrated hydrocarbons/shows, but from rock-eval PI data the lack of shows were confirmed. These analyses also proved excellent source rock potential in the Spekk Formation, although more gas-prone than further to the west an