A modified model for aquathermolysis and its application in numerical simulation

Steam injection can significantly reduce the viscosity of heavy oil. In addition to physical effects, chemical reactions such as aquathermolysis also make a difference. However, the current numerical simulators do not include the characterization for the aquathermolysis reactions, making it unable to analyze directly the effect of the aquathermolysis reactions using numerical simulation. To solve this problem, a basic model of aquathermolysis reactions for numerical simulation is established in this paper. After dividing the oil components reasonably, a modified chemical equation is well defined. And the pre-exponential factors and activation energies are also calculated. Afterwards, this model is implemented into the numerical simulator CMG-STARS, and the results with and without the model are compared, to analyze the mechanisms of aquathermolysis reaction for increasing production. The results indicate: (1) the numerical simulation results with the aquathermolysis reaction model are more consistent with field results (2) aquathermolysis reactions can further reduce the viscosity of heavy oil, increase oil production, and reduce the water saturation near the well bore area.