Geophysical Technologies for Detecting Underground Coal Mine Voids:
An Interactive Forum
Directional Drilling Technology
Presenter: John Wood, Vice-President, Marketing
Firm/Organization: Target Drilling, Incorporated
Mailing Address: 5134 Oak Road
Jefferson Hills, Pennsylvania 15025
Horizontal, inseam, directional drilling is the most reliable and accurate method to locate abandoned mines or verify the absence of abandoned mines. Directional drilling, the art of steering a borehole along a desired path, has been used by mining industry to degasify coalseams in advance of mining and explore geologic anomalies such as faults, washouts, intrusions or burn zones. In the last six years, Target Drilling has employed directional drilling techniques and its DDM - Mecca surveying technology to either locate or verify the absence of abandoned mines.
Intercepting an abandoned mine by drilling into it provides only single point information regarding the abandoned mine's location. Multiple intercepts are possible with multiple boreholes or multiple sidetracks from a single borehole, but they do not provide an outline that delineates the extent of mining. Additionally drilling into the abandoned mine may create more problems for the mine operator than answers. A drill hole could provide a conduit for water or bad air to enter the active mine.
A more prudent strategy for a mine operator may be to drill a long horizontal inseam borehole that does not intercept the abandoned mine. Its purpose is to verify the absence of old mine workings. The borehole would be drilled to shield projected current mining from the abandoned mine. This type of horizontal borehole provides positive proof that abandoned mine works will not be intercepted by the current mining.