The Huntly coalfield has significant coal deposits that contain biogenically-sourced methane. The coals are subbituminous in rank and Eocene in age and have been previously characterised with relatively low to moderate measured gas (CH(4)) contents (2-4 m(3)/ton). The CO(2) holding capacity is relatively high (18.0 m(3)/ton) compared with that of CH(4) (2.6 m(3)/ton) and N(2) (0.7 m(3)/ton) at the same pressure (4 MPa; all as received basis). The geothermal gradient is also quite high at 55 degrees C/km. A study has been conducted which simulates enhancement of methane recovery (ECBM) from these deposits using a new version of the TOUGH2 (version 2) reservoir simulator (ECBM-TOUGH2) that can handle non-isothermal, multi-phase flows of mixtures of water, CH(4), CO(2) and N(2). The initial phase of the simulation is CH(4) production for the first 5 years of the field history. The model indicates that methane production can be significantly improved (from less than 80% recovery to nearly 90%) through injection of CO(2). However, although an increase in the rate Of CO(2) injection increases the amount Of CO(2) sequestered, the methane recovery (because of earlier breakthrough with increasing injection rate) decreases. Modeling of pure N(2) injection produced little enhanced CH(4) production. The injection of a hypothetical flue gas mixture (CO(2) and N(2)) also produced little increase in CH(4) production. This is related to the low adsorption capacity of the Huntlycoal to N(2) which results in almost instantaneous breakthrough into the production well. (C) 2008 Elsevier B.V. All rights reserved.