6507/7-9

General

Well 6507/7-9 was drilled in the Northern part of the Haltenbanken area, near the crest of the Heidrun Field structure, at the proposed site for the production platform. The well was a pilot hole for the Heidrun Field production wells. It should evaluate the top 150 m of sediments below seabed as foundation for the Heidrun Production Platform, and it should drill to 850 m RKB to ensure that the section to be penetrated by the conductors and surface pipes for all production wells, is free of shallow gas. A site survey had detected five shallow gas anomalies at 505, 558, 609, 708, and 762 m.

Operations and results

Appraisal well 6507/7-9 was spudded with the semi-submersible installation Treasure Hunter on 4 August 1987 and drilled to TD at 850 m in Pliocene sediments of the Naust Formation. No significant problems were encountered during drilling. The well was drilled all through with seawater and pre-hydrated bentonite and returns to the seabed. A sub-sea camera was monitoring the wellhead area.

Boulders were encountered between 380 m and 400 m, but created no torquing problems while drilling. Wire line logs identified sands at 600 to 612 m, at 695 to 698 m, and at 749 to 757 m. Gas bubbles were observed emanating from the wellhead while drilling the sand at 600 - 612 m. The gas bubbles decreased after drilling the section and ceased while circulating seawater around to the seabed, indicating hydrostatic pressure. The other sands produced no gas bubbles to surface, and none of the sands showed any signs of high resistivity. It was concluded that shallow gas should not be a problem in drilling future wells from the Heidrun Platform on this location, although shallow gas-filled sands in neighbouring locations could not be excluded.

No cores were cut and no wire line fluid samples taken in this well.

The well was permanently abandoned on 8 August 1987 as a dry well

Testing

No