Chemical Aspects of In-Situ Combustion - Heat of Combustion and Kinetics

After general remarks on the oxidation reactions of hydrocarbons involved in in situ combustion, the heat releases are estimated and a formula is derived for computing the heat of combustion in the high temperature zone. Then a theoretical discussion of reaction kinetics in porous media is presented and applied to the in situ combustion processes. It is observed that there is some similarity between the kinetics of reverse and wet forward combustion processes. Furthermore, the influence of rock matrix properties on crude oil oxidation is illustrated by differential thermal analysis experiments. This observation is of great importance for practical applications. Some information concerning the use of low temperature oxidation data and the value of the reaction order with respect to oxygen partial pressure is derived from the interpretation of reverse combustion experiments using a numerical model. (16 refs.)