Underground » Ventilation, Gas Drainage and Monitoring
The project is centred on improving the understanding and accuracy of gas reservoir modelling applied to coal mining. It covers a description and evaluation of the input parameters, primarily gas content, permeability, relative permeability, gas sorption capacity, desorption time constant, porosity and compressibility.
It defines uncertainty associated with parameter measurement and estimation and uses this to structure the parameter ranges applied to sensitivity modelling.
A program of inter-laboratory isotherm testing is undertaken.
Main findings are:
- Improved means of correcting gas content data for modelling (Qm to QT) and isotherm data for temperature.
- Derivation of desorption time constant from fast desorption gas content testing.
- Better understanding of the factors controlling reduced efficiency toward the ends of gas drainage boreholes, with implications for better in-seam gas drainage design.
- The main source of discrepancy between laboratories for isotherm testing is in measurement of relative density.
- Isotherm determinations on an "as received" moisture basis are a better fit to field measured desorption pressures than "equilibrium" moisture tested isotherms.
- Improved understanding of parameter sensitivity and the derivation of a new set of sensitivity matrices.