Mathematical model for one-dimensional oil displacement by steam injection with solvent addition

Recently, co-injection of steam and solvent has shown to be an attractive technique to increase oil recovery, combining the advantages of viscosity reduction due to the heat transfer achieved from steam injection with the benefits of mass transfer obtained from miscible flooding. In this work, the problem of one-dimensional displacement of oil by steam injection combined with solvent is analyzed. The mathematical model is based on the mass conservation of components oil and solvent, and conservation of system energy. The solution, composed by shock and rarefaction waves and constant states, is obtained using the method of characteristics. Different solution structures were found for particular sets of reservoir-fluid system parameters, which are defined by the ratio between the value of Henry's constant and the system pressure. The results presented here may be used for fast and efficient evaluation of technical aspects of the best Enhanced Oil Recovery method for a particular field, specially for thin shallow viscous heavy oil reservoirs. This model is also useful for the development of streamlines simulators, where gravity and capillary effects are neglected.