Evaluation of heat release caused by low-temperature oxidation of heavy oil and its SARA fractions under isothermal conditions

Abstract

© 2020 Elsevier B.V. During in-situ combusiton, the oils in most of the area before the combustion front encounter low-temperature oxidation (LTO) reactions under relatively isothermal conditions in a long time, and heat release of LTO significantly influences the quality of formed fuel. This work is aimed at examining the heat release of LTO of one Xinjiang heavy oil and its saturates-aromatics-resins-asphaltenes fractions using isothermal high-pressure differential scanning calorimetry tests. Furthermore, the widely-accepted LTO reaction pathways of hydrocarbons are summarized. The results indicated that the Xinjiang heavy oil, aromatics, and resins experienced the increased heat release from 200 to 250 ℃ and from 300 to 350 ℃ due to their elevated oxidation rate, and the decreased heat release from 250 to 300 ℃. Thus, to build a stable combustion of the oil, it is key to overcome the action energy barriers between 250 and 300 ℃.