Speaker
Description
China’s energy landscape is characterized by abundant coal resources, limited oil reserves, and a relatively low natural gas endowment. While coal reserves within a shallow depth of 500 meters are nearing depletion, deeper coal deposits, particularly those exceeding 1000 meters, account for 53% of the total reserves. These deeper reserves hold significant potential for gasification, which could produce coal equivalent to natural gas resources ranging from 272 to 332 × 10^12 m^3—approximately three times the volume of conventional natural gas reserves. This underscores the urgent need to develop safe and efficient methods to exploit these deep coal resources.
Underground Coal Gasification (UCG) is a green technology that converts solid coal into gaseous fuels by initiating subcontrolled underground combustion. This process generates combustible synthesis gases such as CO, CH₄, and H₂, enabling the clean mining and utilization of coal resources located in deep and otherwise inaccessible areas. Although UCG in deep seams primarily relies on injection and production controls, the lack of transparency hinders the identification of optimal operational parameters. Numerical simulation serves as an effective tool to gain a comprehensive understanding of underground coal processes.
In this study, we developed a multicomponent Thermal-Hydraulic-Mechanical-Chemical (THMC) model that accounts for the evolution of porosity and permeability. The finite volume method was employed for the spatial discretization of flow and heat transfer equations, while the finite element method was utilized to discretize mechanical equations. An iterative solution strategy was implemented to effectively manage the coupling between different fields.
The compositional flow model was validated by comparing its results with those obtained from CMG, and the coupled hydro-thermal model was validated against COMSOL Multiphysics. This study incorporates three solid components in UCG: coal, char, and ash, as well as common gas components, systematically analyzing the changes in these constituents. The impact of parameters including gasification agent, solid concentration, well pattern, and initial water saturation on production was evaluated. The results indicate that the kinetic reaction rate is controlled by temperature, with different reactions occurring at various heating temperatures, thereby influencing the fluid composition. Additionally, the study analyzed the evolution of porosity and permeability, as well as cavity development during the UCG process.
| Country | China |
|---|---|
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