Underground » Ventilation, Gas Drainage and Monitoring
The project was undertaken by CSIRO Petroleum with the broad objective of improving the basis for gas outburst risk assessment. The roles of coal permeability and strength in gas outburst mechanisms were investigated with particular reference to their spatial variability on a length scale comparable to mine development workings.
The main technical achievements of the project comprise
- Measurement of permeability in situ at multiple points within an area of approximately 450m2 of the Bulli coal seam. Special equipment was developed by CSIRO Petroleum for this purpose.
- Measurement of permeability, strength, and sorption isotherms of core samples recovered at distributed points within the in situ test region. New application of a rapid, portable method of coal core strength measurement is demonstrated.
- Assessment of the statistical variability and length scale effects of the measured data
- Stochastic simulation of gas outburst mechanisms using Monte Carlo methods and the CSIRO gas outburst model, using the statistical variability of the measured data as input. The outputs indicate that gas outburst can be strongly sensitive to permeability variation and moderately sensitive to strength variation.
The project outcomes suggest that application of this stochastic modelling approach could provide quantitative probability estimates for outburst risk analysis, as a useful adjunct to current methods of outburst risk assessment. Further steps for development of the approach, and the need for mine operator collaboration, are identified.