Analysis of Spontaneous Capillary Imbibition for Improved Oil Recovery

Abstract Spontaneous water imbibition is an important recovery mechanism in water-flooding particularly in naturally fractured reservoirs. Scaling the core test data of spontaneous capillary imbibition with different injection fluids is crucial to properly design improved recovery methods and to predict their performances. Spontaneous capillary imbibition experiments were performed under static co-current conditions, and recovery curves for brine and chemicals solutions were used for scaling the data in different cores and different interfacial tensions. Capillary Pressure and global mobility at water saturation behind imbibition front (Swf) were also extracted from the imbibition data of brine and chemical solutions. Relative permeability experiments were conducted at initial water saturation (Swi) and after imbibition. Spontaneous imbibition of chemical solutions produced higher ultimate oil recoveries than brine imbibition. The scaling approach proposed by Li and Horne yielded satisfactory correlations for all the cases. Water relative permeability curves measured after brine imbibition showed close agreements with those measured at Swi, which suggests that we can save substantial time by sequentially conducting spontaneous imbibition and flooding tests. Finally, the global mobility was evaluated with those calculated at Swf from imbibition data and those calculated from the relative permeability data.