VLI Drilling is the world’s largest and most experienced supplier of underground in-seam directional drilling services. Typical of the services we provide are

  • Gas drainage drilling to mitigate the risk of outburst / inrush. This generally comprises one or more of the following -

  • Pre drainage drilling – typically flanking holes for development headings and candelabra patterns for longwall block drainage

  • Post drainage drilling – VLI successfully pioneered Horizontal Goaf Hole (HGH) drilling in 2010 at Ravensworth coal mine – this is now a recognised and much utilised practice.

  • Cross measure drilling – used as a tool to intersect and drain gas from those nuisance plies, often thin, and either above or below, the mining section. 

  • Water drainage drilling, also to mitigate the risk of outburst / inrush, or simply to drain wet coal. A water drainage hole is initially drilled to target utilising the standard 96mm diameter drill bit. Following this, if required, the hole can be reamed to a larger diameter to facilitate greater water flow. 

  • Exploration drilling.

  • Opencut highwall drilling.

  • Coring, is an integral tool used for gas compliance testing ahead of development and strata sampling, generally for hardness testing.


Drilling can be used as a tool to delineate and provide definition around known or anticipated geological structure. For example, to determine the extent and throw of a fault, the extent and thickness of a dyke, or simply to prove that neither lies in the path of mine development.

Drilling is also used to confirm the seam profile and thickness, as well as roof and floor conditions, thus providing a degree of certainty ahead of mine development.


The accuracy of directional drilling is an accepted tool for determining clear ground ahead of mine development, particularly useful in areas of abandoned mine workings.


VLI Drilling has the necessary equipment, and as equally important, the appropriately qualified and experienced personnel, to undertake all of these tasks.


In addition to the underground workforce, we have a Technical Services department which can provide hole designs in accordance with the client’s requirements, interpret the drilling information, and supply “as drilled” data direct to the mine plan.


VLI Drilling is the industry leader in in-seam directional drilling, providing an all encompassing service to the underground coal mines of Australia, China, Europe and the United States.