Study on catalytic combustion characteristics and parameter optimization of underground combustion heaters for in-situ oil shale extraction

Abstract:

To address the issues of environmental pollution and energy efficiency in the in-situ conversion and exploitation of oil shale， this study proposes an energy recycling method that involves recovering methane-rich waste gas generated from the downhole process and utilizing it as a fuel for a catalytic combustion heater. In this research， a combined approach of catalytic combustion and porous medium combustion was adopted， with methane as the fuel. A two-dimensional axisymmetric model was constructed to systematically simulate the effects of pore diameter， gas injection rate， and methane mole fraction on combustion performance. The results indicate that： reducing the pore diameter can significantly enhance methane conversion rate and exhaust gas temperature； variation in the gas injection rate has a negligible impact on combustion performance； under fuel-lean conditions， minor changes in methane concentration lead to limited improvement in the conversion rate. This study provides a theoretical basis for the resource utilization of methane from downhole waste gas in oil shale operations and the optimized design of combustion heaters， offering significant engineering reference value for advancing the green extraction of oil shale.