Thermogravimetric parameters of the oxidation of organic matter and asphaltenes from the rocks of the Permian deposits of heavy oil field before and after catalytic hydrothermal treatment

Abstract

In this work, on the example of rock samples from Permian deposits of the heavy oil field from the depth interval 117.5–188.6 m, a comprehensive study of the composition of oil-saturated rocks, as well as thermogravimetric parameters and kinetics of oxidation of organic matter (OM) and extracted asphaltenes before and after catalytic hydrothermal treatment was carried out of the rocks. It was shown that rocks with different mineral composition, OM content, and group composition of oil extracts also have different quantitative characteristics of the thermal effect in the processes of OM oxidation. According to the DSC data in the range of 20–600 °C in air atmosphere, several exothermic effects of chemical reactions of OM at stages low-temperature (LTO) and high temperature oxidation (HTO) oxidation were fixed indicating various destructive processes. By the TG/DTG method was shown that asphaltenes, regardless of the chemical nature of OM, have a similar and almost identical set of mass loss peaks. Catalytic hydrothermal treatment of the rock samples at 300 °C in CO2 media in the presence of a catalytic composition based on transition metal carboxylates (Fe, Co and Cu) led to a significant increase in the content of saturated and aromatic hydrocarbons in produced oil extracts due to the intense destruction of resins and asphaltenes. The presence of the catalyst composition in the reaction system leads to a decrease in the initial temperature of asphaltenes oxidation by almost 10 °C, as well as to a decrease in the activation energy by more than 1.5 times as compared to asphaltenes from the original rock. The research results show that the use of thermal and catalytic methods is promising for the successful implementation of the residual oil-bearing potential of productive strata of the Permian deposits of Tatarstan.