Numerical Simulation of Counter-Current Spontaneous Imbibition, with Focus on Scaling Methods

Oil production using water flooding is probably the most widely used technique in secondary oil recovery in conventional and fractured reservoirs. Oil recovery mechanisms during water flooding in these two reservoir types is completely different and more complex in the latter compared to the former. Experiments have shown imbibition dominated flow regime from matrix to fractures in fractured formations under influence of capillary forces. Spontaneousimbibition may take place concurrently, in which water and oil flow in the same direction, or counter-currently, in which oil and water flow in the opposite directions. In this study, the counter-current spontaneous imbibition is numerically modeled, in both cylindrical and Cartesian coordinates in one dimension. Using the developed mathematical model, the impact of some of the pertinent parameters on imbibition rate are examined. Usuallyrecovery in reservoir is predicted by scaling-up of experimental and simulation data at laboratory scale. In order to scale recovery data, dimensionless groups have been introduced over time. Based on the results of this study, the effects of higher water and oil viscosities have been foundto reduce the oil recovery over time. It has also been evident that as initial water saturation becomes higher at the beginning of imbibition process, oil recovery decreases. Based on the scaling analysis of this study, it became evident that Rapaport dimensionless group better generalize the results than that of Ma group as long as the oil and water viscosity are not to be scaled, otherwise Ma group would be preferred.

کلیدواژه ها:

Water flooding ، Fractured reservoir ، Spontaneous imbibition ، Numerical modeling ، Scaling-up ، Counter-current flow