Research on Interaction Mechanism and its Applications of Methane Migration Process in Low Permeability Coal Seam

摘要

China's coal seam there are the characteristics of low permeability and strong adsorption and slow desorption, it is difficult to form the industrialization of coal bed methane, low permeability coal seam methane adsorption-desorption-diffusion-seepage are mutual control migration process. There are more prominent feature of low permeability deep coal seam methane migration process affected by solid-fluid coupling interaction due to the considerably high porosity pressure and geology stress in the deep coal bed gas exploitation. Low permeability coal-bed methane migration process control mechanism are first researched in this paper. Low permeability dual-porous media, multi-component fluid, non-steady-state, non-equilibrium coal-bed methane migration nonlinear solid-fluid thermal coupling mathematical model are established base on deep low permeability reservoir itself properties and properties of fluid flow coal seam, and the mode can show the interaction mechanism of coal seam methane migration process. In addition, this paper analyzes the influential regulations of diffusion parameter, permeability and threshold pressure on production parameter. The production increase regulation by carbon dioxide injection worthless mining coalbed or in deserted coal mine seam are researched systematically, for China's low permeability coal seam gas development and disposal carbon dioxide utilization worthless mining coalbed or deserted coal mine coalbed provide a theoretical basis.