Projects
Pilot LARGE DIAMETER BOREHOLE hole G 272 RAG BERGWERK WEST
Drilling of a large diameter borehole, using the raise bore technique, for the ventilation borehole G 272. The borehole was completed on schedule with the help of a special roller cutter. The depth was 583 m in rock comprising sandstones and sandy shales. Increased wear on roller cutters was experienced due to the very hard, abrasive layers of rock.
In order to enlarge the ventilation borehole G 272 at a later date, a large diameter borehole had to be drilled for muck evacuation. High vertical drilling accuracy (0.5 %) was required. A target bore system was used to drill a pilot hole with a diameter of 311 mm. The raise borer subsequently enlarged the pilot hole to a diameter of 1.8 m.
