Surface borehole

Surface Borehole

Surface Borehole are a connection between the surface and the minig area by a vertikal borehole. Most used vertical gob wells are developed from the surface in advance of mining. The usual practice is to drill large-diameter (up to 300 mm) vertical gob wells in advance of mining to within 10 to 30 m above the working coal seam.

A special kind of surface degassing borehole are used in eastern countries. This borehole with a diameter up to 2000 mm locate in a raodway were the longwall starts. The exhausted gas mixture contins mostly less than 4% CH4. The volume is up to 2000 m3 / min.

Boreholes for degassing with more than 25 % CH4

This typ of boreholes are often used in gassy mines to extract the gas from the roof of the layer. The extracted gas contains

Ventilation Borehole

Ventilation boreholes are a part of ventilation system of the mine. They are also used for special degassing purposes. Often a great part of the methane is released in the gob, specially near the longwall. The function of the ventilation borehole is creating a direction of depression for the gas in the gob.