Using DSC/TG/DTA techniques to re-evaluate the effect of clays on crude oil oxidation kinetics

• Three models are used to calculate kinetic parameters of crude oil through DSC curves.
• Clay minerals exhibit good catalytic effects on crude oil oxidation.
• Kinetics computation based on a single heating rate is not so accurate and reliable.
• The discrepancy of calculated results can guide reservoir simulation work.

This study was performed to re-evaluate the exothermic behavior of crude oil+clay minerals by differential scanning calorimetry (DSC) technique from the view of thermal analysis. It is observed that KekeYa crude oil shows much greater amount of heat generation at low temperature oxidation (LTO) stage than high temperature oxidation (HTO) stage, which may be due to the high content light components of crude oil. Besides, all clay minerals exhibited a good catalytic effect on oil oxidation, especially in HTO stage. In this paper, it revealed that illite shows the highest catalytic ability for crude oil oxidation which is slightly different from the conclusion of smectite as the best catalyzer in our previous study performed by thermogravimetry/derivative thermogravimetry (TG/DTG) techniques. However, kaolinite was not the best catalytic agent for crude oil oxidation concluded in the two studies. Some new recognition was achieved by comparing the results with previous study. The kinetic computations based on a single heating rate may be not accurate and reliable, which should be responsible for the difference of clay catalytic ability. The calculated kinetics parameters of different models do not show significant variation which can provide important guidance for better understanding the catalytic effect of different clays on crude oil oxidation as well as reservoir simulation studies. Hence, we can unitize this difference for reasonably adjusting oxidation kinetics parameters obtained by different kinetic models to match experimental results.