This paper discusses the effects of some parameters on the in-situ combustion process. The paper is in two parts. The first part discusses a laboratory in-situ combustion tube run. Important design parameters such as fuel concentration, air requirement, oxygen utilization efficiency and combustion front velocity may be determined from the analysis of laboratory tube run data. The second part of the paper discusses numerical simulation of the laboratory tube run and results from in-situ combustion simulation studies. A thermal simulator was used to investigate the effects of relative permeability, rock thermal conductivity, heat losses, API gravity of oil, initial conditions, oxygen concentration, and other parameters on fuel availability and combustion front velocity.
Results from simulation studies show that oil viscosity, residual oil saturation (gas/oil system) and oxygen mole fraction in the injected gas should have the greatest effect on fuel availability. Relative permeability data and rock thermal conductivity also affect the amount of fuel available for combustion. Factors which may cause an increase in combustion front velocity may also cause an increase in the amount of fuel burned if the heat front moves slower than the combustion front. The use of a thermal simulator for this study made it possible to study a wide range of parameters which would involve a substantial effort to investigate experimentally.