Theoretical Modeling of Reinfiltration Process in Naturally Fractured Reservoirs: A Comparative Study on Traveling Liquid Bridges and Continuum Film Flow Approaches

Most of the Iranian oil reservoirs are naturally fractured. Reinfiltration is a key process which controls oil flow from the upper to the lower matrix block. However, theoretical modeling of fracture aperture as well as fracture dip angle effects on flow rate of drained oil during reinfilteration process remains a topic of debate in the literature. Moreover, there is no reported experience in the literature that compared the oil velocity predicted by traveling oil bridges and continuum film flow approaches. In this work reinfiltration process is modeled through two different approaches: discrete traveling liquid elements and continuum film flow along inclined fractures. For a case study reported in the literature, the oil velocity at various fracture aperture as well as fracture dip angle was predicted and compared using both approaches. The results of this work confirmed that the geometry of fractures between matrix blocks plays a crucial role on drained oil during reinfiltration process. By decreasing fracture aperture or fracture dip angle the oil velocity modeled by liquid film flow approach decreases, it might be due to more time available, for the droplets and film to be adsorbed on lower block; therefore reinfiltration effect increases. It has been observed that the velocity of traveling liquid bridges is maximized for fracture aperture close to 0.5 mm. A surprising result, for the case studied here, is that there are critical values for fracture aperture and fracture dip angle, close to 1 mm and 15 degree respectively, in which after those the velocity of traveling liquid elements is higher than that predicted by liquid film flow approach. The results of this work might help to obtain an independent transfer function for dual permeability model incorporating the interaction between matrix blocks which might improve the reliability of simulators for evaluation of naturally fractured reservoirs.