Reacting Flows in Porous Media: Complex Multi-phase, Multi-component Simulation

Modelling of multi-component, multi-phase reacting flows in porous and fractured media is investigated with examples on spontaneous combustion of coal and the extraction of coalbed methane. Chemical reactions, adsorption, gaseous diffusion and changes in transport properties (porosity and permeability) are of particular importance. These matters along with numerical dispersion and stiffness are discussed in the first four chapters. A new power law model for representing the diminishing reaction effect during self-heating reactions was proposed, and compared with existing models. A modified version of the TOUGH2 simulator is used for modelling the adiabatic method for testing the reactivity of coal samples. The results agrees well with experimental measurements for coal samples from different mines in New Zealand and Australia. Moisture effect on the reaction rate was then introduced to TOUGH2 using a new two-phase equation of state (EOS) module. Finally the production of methane from low rank coalbeds was investigated. A new and versatile coalbed methane simulator was developed.