(132b) Application of an Integrated Multiphysics Simulator to Underground Coal Gasification

Underground coal gasfication (UCG) is a problem rich with complexity and interconnected physical phenomena. It is also an opaque process, with limited operational data available and with the only clear picture of cavity evolution coming after the fact. A comprehensive UCG simulator has been developed, which is capable of accounting for the multiphysics complexity of UCG, to provide a better understanding of UCG dynamics (e.g. design, operation, monitoring, and hazards analysis). The simulator breaks UCG into six parts, each corresponding to a particular aspect of UCG physics, and each spawning a particular computational tool designed for a particular application. Each computational tool is tied to the others through a simulation manager, which manages grids, discrete elements, communication overhead, input/output, and transfer of information among components. The overarching UCG model that results is entirely novel, combining detailed models for thermal-hydrology, cavity gas, rubble inside the cavity, boundary evolution, wall reactions, and geomechanics into a single simulator and a single algorithm in an unprecedented way. The simulator is able to predict many quantities, including the evolution of the cavity boundaries, the potential for surface subsidence, and the impact of gas mixing and reaction in the cavity on cavity evolution. Several improvements have been made to the simulator over the past year, including rubble model improvements, identified in prior studies as a source of inaccuracy in comparisons with data for a simulation of Hoe Creek 3, improvements to the geomechanical collapse model, and fully coupled 3D cavity gas and rubble zone models. Results from simulations of the Rocky Mountain field tests are presented and compared with experimental data. Additional challenges and areas of interest for future development are identified.