Gas Emission Expert Model For Abandoned Coal Mines

This project is a continuation of ACARP Projects C13007 and C14080 (Lunagas 2005 & 2006) which updates previous mathematical formulae and decline curves and utilises new data, information and the research findings.

The research has consolidated the knowledge of gas emission characteristics of coal mine goaf in Australia into a form which enables emission predictions to be made using limited input data. The fundamental principles are encapsulated within 'Coal mine goaf gas predictor - Australian version' (CMGGP-A) professional engineering software. This easy to use tool is designed to predict the decline of methane emissions and calculate gas reservoir capacity of underground coal mine goaf. The method for estimating abandoned coal mine and goaf area methane potential is applicable to both dry and flooding mines and also takes into account coal mine methane utilisation options.

The main research findings are:

· Coal mine goaves in Australia have been classified in relation to the mining, hydro-geological and ownership conditions;

· Coal mine goaf methane resource estimated using constrained emission decay curves and related mathematical formulae avoids difficulties of identifying all gas sources and their magnitudes, full knowledge of the latter is problematic in practice;

· The proposed coal mines goaf have been classified in relation to the case studies performed for selected NSW and QLD underground coal mines which selected eight various categories in relation to the similar mining, gassy and geological conditions;

· If key data are available the empirical curves and gas reservoir simulation will provide a rapid and practical prediction of closed or abandoned coal mine methane potential; and

· Where some typical data are lacking site investigation may be required involving variously drilling, gas monitoring, water and gas pumping tests.

A dry mine gas emission decline simulation 'Drysim' (Lunagas 2006) has been extended to allow for the effects of flooding to be modelled 'Wetsim' (L Lunarzewski, D Creedy 2006) as well as to calculate gas reservoir parameters and the ability for venting, flaring or utilising coal mine methane from underground coal mine goaf. Results derived from this research have been incorporated into the CMGGP-A software to facilitate modelling of emissions in both dry and flooding conditions to provide a practical estimation of coal mine goaf methane production potential.

The software will run on a PC with Windows XP or Vista operating system and can be used by individual specialists, coal mines and/or other institutions involved in coal mine closure, coal mine methane utilisation and greenhouse gas emissions reduction.

The Lunagas CMGGP - A software comprises three main sections:

· Coal mine parameters - allows data entry for calculating decline curves for both dry and wet mines;

· Gas reservoir characteristic - allows entry of geological data for calculating the available gas reservoir; and

· Methane decline curves and gas reservoir charts - shows the results of calculations made based on data from the above two sections.

This software (CMGGP-A) is available directly from Lunagas, please email lunagas@ozemail.com.au  There are two options as follows, all prices are current as at October 2009:

· Pay a fee for use of software, of $500 net mine and have Lunagas undertake the data collection, processing, simulation, interpretation and reporting at their standard charge rate of $200 net per hour; or

· Purchase MMGGP-A software for $6,000 net including user manual and half day user training.

An e-newsletter has also been published for this project, highlighting its significance for the industry.