Comparison of RTM results of Time-lapse imaging in Foam-assisted EOR

Abstract

Due to the oil demand staying high in the world, the technology of enhanced oil recovery (EOR) plays an important role to optimize the oil production from the existing reservoirs. Among the EOR methods, foam-assisted EOR, i.e., one of the chemical methods, has drawn attention for its enhancement in the sweep efficiency and in the incremental oil recovery. Although the mechanisms of the foam-assisted EOR have been revealed both in microscopic and macroscopic ways, methods for monitoring the movement or the alteration of pore fluids in the reservoir have not been fully established yet. Since the behavior of seismic waves reflects the change in the pore fluids where seismic wave propagates, we hypothesized that seismic methods could capture the movement of pore fluids in the reservoir. For testing this hypothesis, we conducted numerical experiments on the time-lapse monitoring of a reservoir before and after the application of foam-assisted EOR using reverse time migration (RTM) in our previous study. Our numerical results indicated that we could detect the advancement of injected fluids by RTM and showed the effectiveness of seismic exploration methods. However, in our previous study, we only utilized the vertical component of recorded data for RTM imaging and the effect of the recorded component (vertical and horizontal) on the imaging has not been fully investigated. Therefore, in this study, we conduct numerical experiments to confirm how the difference in the component of recorded data used in RTM procedure affects the resultant subsurface image. From obtained results, it is indicated that the integration of analyses of RTM results obtained from two components would help the interpretation of the results.