Gas-phase combustion within porous media at moderate pressures

Gas-phase combustion within porous media has many potential applications in the oil and gas industry. Some of these applications are associated with: air injection based improved oil recovery (IOR) processes, formation heat treatment for remediation of near well-bore formation damage, final disposition of waste and/or sour gases, downhole steam generation for heavy oil recovery, in situ preheating of bitumen for improved pumping, increased temperatures in gas condensate reservoirs, and improved gas production from hydrate reservoirs. The available literature on gas-phase flame propagation in porous media is limited to applications at atmospheric pressure and ambient temperature, where the main application is in designing burners for combustion of gaseous fuels having low calorific value. The effect of pressure on gas-phase combustion in porous media is not well understood.; Accordingly, this thesis will describe an experimental study aimed at establishing fundamental information on the various processes and relevant controlling mechanisms associated with gas-phase combustion within porous media, especially at moderate pressures. A novel apparatus has been designed, constructed and commissioned in order to evaluate the effects of controlling parameters such as operating pressure, gas flow rate, type and size of porous media, and equivalence ratio on combustion characteristics. The experiments were carried out using three different porous media and the effect of operating pressures from atmospheric (88.5 kPa or 12.8 psia) to 777.7 kPa (112.8 psia) have been studied. Lean mixtures of natural gas and air (5.1, 5.4 and 5.6 percent of natural gas, by volume) were used. It is shown that the velocity of the combustion front decreases as the operating pressure of the system increases, and during some test operating conditions, the apparent burning velocities were over 40 times higher than the open flame laminar burning velocities.