Improved sweep efficiency through seismic wave stimulation
Enhanced oil recovery as a result of earthquake events has been repeatedly observed and reported. The main advantage of a seismic wave-based EOR is that it is not costly and is easy to deploy. However, the method has not yet been fully investigated; the production enhancement mechanisms need to be identified and confirmed. This thesis shows a possible production mechanism and preliminary estimate of incremental oil recovery due to seismic wave stimulation. The production mechanism is improved sweep efficiency through viscous cross-flow between different permeability layers of a reservoir as a result of fluid pressure oscillations. In this thesis, we studied a possible viscous cross-flow generation between a fracture and a rock matrix of a fractured reservoir model as a result of fluid pressure oscillations. We considered time-harmonic water flooding as a way of sending seismic waves to the reservoir model. To calculate a cross-flow pressure gradient, we investigated oscillatory pressure propagation equations within the rock matrix and the fracture of the reservoir model. According to our results, the volume of the mobilized oil because of the time-harmonic water flooding during one day of stimulation from the fractured reservoir model is in the order of several barrels.