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Being partially beneath Paparoa National Park, and accordingly constrained by stringent surface environmental conditions, makes the Pike River coalmine a prime candidate for in-seam directional drilling, says the company’s general manager Peter Whittall and geologist Jimmy Cory. Forty-six surface holes were drilled into the permit area in the Paparoa Ranges 50 kilometres northeast of Greymouth to plot the main target resource, the Brunner Coal Measures. Two of these, at either end of the escarpment that houses the seam, have since been extended to the mine’s secondary target, the Paparoa Coal Measures 200 metres below the Brunner. The latter of the two was drilled in-seam by Valley Longwall Drilling last year, and revealed the Paparoa seam could be as much as nine metres thick rather than the previously estimated two metres. At the West Coast Minerals Conference earlier this year, Whittall said the Paparoa seam could extend the projected 18-year life of the mine, with production costs being minimised by the use of the existing infrastructure. Further in-seam directional drilling will both explore the extent of the Paparoa resource and provide drainage for gas in advance of Brunner mining operations. In-seam directional drilling was developed in Australian coalmines in the mid-1980s, and first used in 1989 at Huntly West in the Waikato.
Q&M Vol.6 No.5 October-November 2009 All articles on this website are copyright to Contrafed Publishing Co. Ltd. |