Volume 62

The reaction mechanisms of different boiling-range pseudo-components in porous media Ying Yang, Renbao Zhao, Bin Liu, Bin Liao, Guanghui Zhou

Abstract

In this work, heavy oil was fractionated into pseudo-components with different boiling ranges via the true boiling point (TBP) distillation method. Kinetic Cell (KC) experiments were conducted to investigate the reaction behaviors of different pseudo-components in both bulk phase and porous media environments. Under bulk phase conditions, the high concentrations of oxygen and hydrocarbons result in intense oxidation reactions of pseudo-components, accompanied by significant changes in temperature and concentration. In porous media, however, the relatively low concentrations of both oxygen and hydrocarbons lead to a substantial reduction in the oxidation reaction rate. Additionally, the increased surface area of crude oil in porous media divides the entire reaction process into two distinct stages: low-temperature oxidation (LTO) and high-temperature oxidation (HTO). A lower heating rate extends the heating duration, facilitating the formation of more activated molecules and thereby decreasing the initial reaction temperature of LTO. Pseudo-components with higher boiling ranges exhibit weaker distillation effects, which means a greater number of hydrocarbon moles participate in the oxidation reaction, generating more COâ‚“ molecules. Conversely, pseudo-components with lower boiling ranges show stronger distillation effects, resulting in smaller changes in the concentration of reactive hydrocarbons and consequently higher reaction activation energy. During the HTO stage, the gradual depletion of hydrocarbon concentrations hinders the reaction between hydrocarbons and oxygen molecules, leading to an increase in activation energy. This work holds significant implications for understanding the in-situ combustion (ISC) process.

Keywords Reaction kinetic, Pseudo-component, Kinetic cell, Oxidation reaction, Distillation, Activation energy