Inseam Boreholes to and Beyond 2000 m with a Combination of Slide and Rotary Drilling

Directional drilling has been the established form of in-seam drilling for gas drainage, exploration and water management for the past two decades. Although there has been a desire to achieve longer boreholes to depths similar to that achieved with surface drilling, seam conditions, equipment capacity and drilling methods have limited in-seam drilling depths. Development into a new area of Metropolitan Colliery required boreholes to depths of 2000 m to provide the required gas drainage. This offered an opportunity to use a combination of slide and rotary drilling similar to that used with Surface to Inseam (SIS) drilling to achieve the required depths. This paper describes the drilling techniques used and presents the results of the drilling.