Study on Hydrothermal Cracking of Heavy Oil under the Coexisting Conditions of Supercritical Water and Non-condensate Gas

Abstract

This study looked at the effects of temperature, water−oil ratio, and the addition of non-condensable gas on the thermal cracking of extra-heavy oil in the lab. The goal was to learn more about the properties and reaction rates of deep extra-heavy oil under supercritical water conditions, which are not well understood. The changes in the composition of the extra-heavy oil were analyzed with and without the presence of non-condensable gas. The reaction kinetics of the thermal cracking of extra-heavy oil were quantitatively characterized and compared between the two conditions of supercritical water alone and supercritical water mixed with non-condensable gas. The results showed that (1) under supercritical water conditions, the extra-heavy oil underwent significant thermal cracking, which led to a significant increase in the amount of light components, the release of CH 4 , and the formation of a new component, coke, which led to a noticeable decrease in the viscosity of the oil; (2) increasing the water−oil ratio could promote the thermal cracking of extra-heavy oil and led to a significant decrease in oil viscosity, indicating a more complete thermal cracking reaction. Moreover, increasing the water−oil ratio was found to facilitate the flowability of the cracked oil; (3) the addition of non-condensable gas intensified the conversion of coke but inhibited and slowed down the thermal cracking of asphaltene, which is detrimental to the thermal cracking of extra-heavy oil; and (4) the kinetic analysis showed that the addition of non-condensable gas resulted in a decrease in the thermal cracking rate of asphaltene, which is detrimental to the thermal cracking of heavy oil.

Synergistic Catalysis of Reservoir Minerals and Exogenous Catalysts on Aquathermolysis of Heavy Oil

“…Common heavy oil viscosity reduction methods include thermal viscosity reduction, chemical viscosity reduction, microbial viscosity reduction, and dilute viscosity reduction. Among the various thermal viscosity reduction methods, steam stimulation (CSS), steam flooding (SF), steamassisted gravity drainage (SAGD), and steam-injection-based combustion of oil layers are the primary techniques [3], but these technologies lead to high energy consumption and have a high environmental impact. Chemical viscosity reduction mainly includes emulsion dispersion viscosity reduction, oil-soluble viscosity reducer viscosity reduction, etc.…”