Study on reaction equations of heavy oil aquathermolysis with superheated steam

Aquathermolysis is an important approach to in situ conversion, a form of heavy oil thermal recovery technology. The aquathermolysis reaction models for high-sulfur heavy oil previously proposed by scholars are not suitable for low-sulfur heavy oil. Additionally, the essence of an aquathermolysis reaction is the change in the heavy oil composition, which cannot be characterized by existing models. To address these two problems, we established an aquathermolysis model for low-sulfur heavy oil, which can characterize the composition change. This model is based on material balance, reaction kinetics, and the Arrhenius equation and includes the aquathermolysis equation, the reaction kinetics model, and the Gaussian reaction rate model. We compared results of the modified model with an experimental model and found the following: (1) The characteristics of aquathermolysis of low-sulfur heavy oil were in accordance with its Gaussian type, (2) the model could predict the composition change of heavy oil more accurately and could more precisely predict the gas reaction rate of low-sulfur heavy oil, and (3) the model has a common applicability for low-sulfur heavy oil of different viscosities.