6507/7-2

General

The well 6507/7-2 was drilled in the northern part of the Haltenbanken area, some 190 km west of the Norwegian coast. It was drilled to evaluate the "B" prospect in the intensely faulted zone that lies at the intersection of the Nordland Ridge in the northeast and the Halten Terrace in the south. The prospect was in a southward plunging horst block formed by a Late Jurassic tensional fault system. The main reservoir interval was anticipated to be the Lower Jurassic sandstone of the Aldra (Tilje) Formation.

Operations and results

Wildcat well 6507/7-2 was spudded with the semi-submersible installation Nortrym on 25 February 1985 and drilled to TD at 3262 m in Late Triassic sediments of the Åre Formation. No significant problems occurred during drilling operations, which went very much according to schedule. The seven-test program was however delayed approximately two weeks due to a premature firing of the Baker Tubing-Conveyed Perforating Guns while running in for DST 4. This necessitated the running of a protective string of 7" casing to cover the perforations (1062.5m to 1072.5m) and enable the testing program to be completed. Additional time was lost due to pulling and repairing the BOP stack after running the protective casing string. The well was drilled with sea water down to 1030 m and with gypsum mud from 1030 m to TD.

Shetland Group sediments were resting directly on the Fangst Group, confirming heavy erosion at the crest of the structure as prognosed. The oldest dating of the Shetland Group was Santonian age, in sediments ca 5 m above top Fangst Group, while the youngest Fangst Group sediments were dated Toarcian-?Aalenian. At 2198 meters gas levels rose, indicating the top of the Jurassic sediments. Associated with the gas show was a rare dull-gold fluorescence on cuttings; however, no cut or staining was evident. The MWD gave little indication of sand through the Fangst Group and very little sand