EFFECT OF WETTABILITY AND SPREADING ON RECOVERY OF WATERFLOOD RESIDUAL OIL BY IMMISCIBLE GASFLOODING

This paper investigates the mobilization and recovery of waterflood residual oil by immiscible gasflooding in 2D glass micro-models under strongly oil- and water-wet conditions. Two oil/water/gas systems, one displaying a positive and the other a negative spreading coefficient (oil over water), were used. The results clearly show the importance of fluid/solid and fluid/fluid interactions on tertiary oil recovery. Oil recovery was highest for the oil-wet displacements where the oil formed thick wetting films. Recovery was considerably lower for the positive spreading system under strongly water-wet conditions where the oil was observed to form thin but continuous spreading films. Recovery was lowest for the negative spreading system under strongly water-wet conditions where no oil films were formed.