Numerical investigation of spontaneous imbibition in an anisotropic reservoir

In this study, co-current spontaneous imbibition in two-dimensional reservoir formations saturated with two immiscible and incompressible fluids is investigated. A computational workbench is proposed assuming that the porosity of the medium is constant however permeability is anisotropic i.e., direction-dependent. Numerical experiments are performed for two geometrically distinct reservoir domains, namely, narrow channel and square duct. The numerical experiments reveal that the dynamics of the recovery significantly depend on the ratio of the vertical to the horizontal intrinsic permeability i.e., anisotropic ratio. Specifically, the front propagation shows a striking dependency on the anisotropy of the medium. This analysis indicates that the cross-flow behavior triggers early water breakthrough and consequently substantial amount of oil/non-wetting phase bypassing. In addition, it is noted that the onset of forced imbibition is regulated by the mean pressure distribution of the underground formation. This article develops a correlation between the oil recovery percentage (%) and the reservoir quality index (RQI). This can predict the oil recovery trend at a particular instance for a given reservoir configuration depending on the corresponding RQI values.

Automated summary

This study investigates the co-current spontaneous imbibition in two-dimensional reservoir formations. The anisotropic ratio between the vertical and horizontal intrinsic permeability significantly affects the recovery dynamics. Cross-flow behavior leads to early water breakthrough and bypassing of oil/non-wetting phase. The onset of forced imbibition is regulated by the mean pressure distribution of the underground formation.