Correlation of Capillary Number Relationships for Sandstone

Abstract

Capillary number relationships are presented for displacement of both residual and initially continuous oil from water-wet consolidated sandstones having permeabilities that varied over about two orders of magnitude. It was found that the critical displacement ratio, (ΔP/Lσ)cr, for the onset of mobilization could be correlated with sample permeability. Relationships between normalized reduced residual oil saturation and capillary number (taken as kwΔP/Lσ) also were correlated satisfactorily. For sandstones, capillary numbers for displacement of continuous oil were lower than values for mobilization of discontinuous oil for down to 50% of normal waterflood residual. Thereafter, capillary number relationships for the two types of displacement were indistinguishable. Conditions for complete recovery of residual oil correspond to values of (kwΔP/Lσ) of about 1.5 × 10−3 as compared with about 2 × 10−5 for onset of mobilization.