Download or read book Investigation of Thermal Effect on the Evolution of Coal Permeability Under the Influence of CO2 Injection written by Hongyan Qu and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated abstract] CO2 is normally injected at low or high temperatures into the targeted coal seams for geological sequestration. Under these injection conditions, coal matrix may swell or shrink due to the thermal expansion and the change in adsorption capacity. This uncertainty of swelling/shrinking complicates the prediction of coal permeability. A fully coupled coal deformation, gas flow and transport, and thermal transport model was developed to address this uncertainty on permeability change. The developed model was implemented into COMSOL Multiphysics, a commercial Partial Differential Equation (PDE) solver, and applied to evaluate the evolution of coal permeability under the combined influence of gas pressure and temperature. These combined effects are evaluated through explicit simulations of the dynamic interactions between coal matrix swelling/shrinkage and fracture aperture alteration, and translations of these interactions to the evolution of coal permeability. The developed model was used to develop a concept of transition from local swelling to global swelling under stress conditions through a series of simulations. In this concept, the fact that coal permeability evolves as a function of time from the initial equilibrium state (both matrix pressure and fracture pressure are equal to the initial reservoir pressure) to the final equilibrium state (both matrix pressure and fracture pressure are equal to the injection pressure) was recognized. The fully coupled model was applied to evaluate why coal permeability changes instantaneously from reduction to enhancement under the free swelling condition as widely reported in the literature. The above concept was extended to the most complex situations where multiple processes (thermal transport, gas transport and coal deformation) are involved...