6507/11-3

General

Well 6507/11-3 was designed to test the Beta Fault compartment of the Midgard Discovery off shore Mid Norway. The Beta segment is a part of the Midgard horst. This horst is defined by NNV trending normal faults. It is separated from the other compartments by a ENE trending cross fault and exhibits true vertical closure at Base Cretaceous level. The primary target was reservoir rocks of the Middle Jurassic Fangst Group with the objective to establish the GWC within a good sand and to perform a DST in a formation not previously being tested (the Ile Formation). The location was chosen relatively high on the structure in case the hydrocarbon contact for Beta was different from what was seen in the Alpha and Gamma structures. The well should reach Triassic rocks or drill to 500 m below the coal reflector. The proposed depth was 3250 m. The pre-drill classification of the well was wildcat.

The well is Type Well for the Ile and Not Formation of the Fangst Group.

Operations and results

Well 6507/11-3 was spudded with the semi-submersible installation Treasure Saga on 3 June 1985 and drilled to TD at 3250 m in the Triassic Grey Beds. While drilling the reservoir, mud weight had to be raised gradually to 1.6 g/cm3 due to high trip gas. Approximately 2 weeks were lost due to a work conflict. The well was drilled with spud mud down to 421 m, with gel mud from 421 m to 868 m, with gypsum/polymer mud from 868 m to 2615 m, and with gel mud from 2615 m to TD.

The average background gas down to the 20" casing point was 0.4% to 0.8% with peaks at 505 m (3.43%), 540 m (1.08%), 576 m (1.76%) and 663 m (1.97%). Methane was the only gas component present. The well proved mainly claystones down to the Fangst Group. The Cainozoic with a total thickness of 1771 m overlies a 271 m Cretaceous sequence. Late Jurassic consisted of 14.5 m hot shale of the Spekk Formation and 39.5 m of silty claystones of the Melke Formation. The Fangst Gr