This document discusses methane drainage techniques used in coal mining. It introduces methane drainage as the practice of removing methane gas from coal seams through wells and pipelines. Underground coal mining faces challenges from coal bed methane, which is traditionally drained using ventilation systems. However, with increased productivity and retreat mining, methane degasification systems implemented before or during coal extraction have become more economical. The document then describes various methane drainage techniques including vertical wells with hydraulic fracturing, vertical gob wells from the surface, inclined wells, and horizontal wells from existing mine openings. It provides more details on vertical wells with hydraulic stimulation and vertical gob wells.

1. VNS INSTITUTE OF TECHNOLOGY
PRESENTED BY:
 VINAY SINGH BRIJESH SHAH

2. INTRODUCTION
Methane drainage, is also called coal
degasification, is the practice of
removing methane gas in a coal seam
and adjoining strata through wellbores,
drillholes, and pipelines.

3. Underground coal mining is the oldest mineral extraction activity and
traditionally faces the challenges of coal bed methane. Coal has the
ability to store large volume of methane gas in it’s micro-porous
structure, which typically get released during coal extraction. In adding
to loss of the value of this resource and its impact on global warming,
methane directly affect mine safety and productivity.
Coal bed methane has to be drained, which is traditionally performed
using a well designed ventilation system. However, due to increase
productivity and trend toward recovery seam, coal mine now have to
deal with increasing amount of coal bed methane. It is found more
economical to implement a methane degasification system before and
/or while extracting coal, with a scale down ventilation system.

4. Technique of methane drainage:
Vertical wells from the surface, with hydraulic
stimulation
Vertical gob wells from the surface
Inclined wells from the surface
Horizontal well from existing mine openings

5. Vertical well from the surface with hydraulic stimulation
Well is drilled through the coal seam .
 Seam is hydraulically fractured to get
large amount of methane.
Generally gas recovery is of high quality.
Efficiency of recovery is 50% to 80%.

6. Vertical gob well from the surface
Gob well is a coal bed methane well that
extract methane from the gob area.
 Short production life and low gas quality.
Used for long wall panel having high
methane quantity.

7. Vertical gob well from the surface
Gob well is a coal bed methane well
that extract methane from the gob
area.
 Short production life and low gas
quality.
Used for long wall panel having high
methane quantity.