Effect of Solubility and Diffusivity of Solvent in Heavy oil on the Performance of the VAPEX Process as an Enhanced Oil Recovery Process

In this work, the VAPEX process is introduced as an enhanced oil recovery process. Then, the solubility of solvent in heavy oil is discussed and solubility of two most common hydrocarbons used in the VAPEX process as solvents are calculated in a certain heavy oil system and their solubility is compared at different reservoir conditions. It was found that n-butane has higher solubility than propane at all temperatures of interest in the reservoir conditions. Also, solubility of both solvents into heavy oil decreases as the reservoir temperature increases. In addition, solubility of n-butane is higher than that of propane at all pressures; but, as the pressure increases, their solubility approaches a constant value, which is the limiting solubility of propane and n-butane at this temperature. Effect of solvent diffusivity on the performance of the VAPEX process was studied. Simulation results show that the diffusion process becomes important and higher recoveries are obtained at low injection rates provided sufficient time is given to the process.

Keywords:

Heavy Oil , Enhanced Oil Recovery , Vapor Extraction , Equation of State , Diffusivity , Solubility