EXPERIMENTAL STUDY ON FOAMED GEL FLOW IN POROUS MEDIA

Foamed gel has the advantages of aqueous foam and bulk gel, widely used in profile modification for oil recovery. Distribution characteristics of the foamed gel in porous media was observed by microscope. With gelling time increasing, bubbles coalescence occurs, and the average diameter of the foamed gel gradually becomes larger. During the subsequent water flooding process, bubble diameter decreases. Through single-core displacement experiments, the several effects on the blocking capability of foamed gel were studied. Blocking capability first increases and then decreases with foam quality, and the best foam quality is 50% in the experiments. Blocking capability first increases obviously with permeability, and then remains almost stable. Although the residual resistance factor decreases with oil saturation, foamed gel has good tolerance with crude oil compared with aqueous foam. Forward injection for subsequent water flooding is better than reverse injection. In a thorough comparison of aqueous foam, gel, polymer, and foamed gel, the blocking capability of foamed gel is the greatest. Cross-linked gel increases the strength of bubble film, and prolongs the blocking duration time. Through dual-core displacement experiments, the effects of permeability ratio and injection rate on profile modification were studied. Along with the increasing of permeability ratio, the foamed gel profile modification effect first increases, and then decreases. When permeability ratio is 7.0, profile modification effect is the best. Profile modification effect decreases with injection rate. The improved oil recovery efficiency for immature foamed gel and subsequent water flooding is 31.3% for parallel sandpack, with permeability ratio of 6.8. Foamed gel has real potential for profile modification in the oil field.