Simulation Study of Underground Coal Gasification in Alberta Reservoirs: Geological Structure and Process Modeling

Underground coal gasification (UCG) as an efficient method for the conversion of the world's coal resources into energy, liquid fuels, and chemicals has attracted lots of attention in recent years. This paper is concerned with a feasibility study of the UCG process for Alberta reservoirs using the three-dimensional simulation of this process based on a unique porous media approach. The proposed approach combines the effects of heat, mass transport, and chemical reactions to achieve this goal. The Computer Modeling Group (CMG) software STARS is used for simulation. The geological structure including coal and layers interspersed between coal seams (claystone layers), the porosity/permeability variation, and the chemical processes with corresponding parameters are considered in the model. Chemical stoichiometry coefficients of the pyrolysis process are calculated from proximate and extended experimental data. Genetic algorithm and pattern search are used for parameter estimation. This model is developed to study UCG in deep coal seams and can be used for production prediction and optimization of the process. The simulation results. such is cavity formation, temperature profile, and gas composition at the producer, are presented. Finally, the results are analyzed on the basis of field pilot tests.