Novel Three-Phase Compositional Relative Permeability and Three-Phase Hysteresis Models

Abstract

SummaryMobility-control methods have the potential to improve coupled enhanced oil recovery (EOR) and carbon dioxide (CO2) storage technique (CO2-EOR). There is a need for improved three-phase relative permeability models with hysteresis, especially including the effects of cycle dependency so that more-accurate predictions of these methods can be made. We propose new three-phase relative permeability and three-phase hysteresis models applicable to different fluid configurations in a porous medium under different wettability conditions. The relative permeability model includes both the saturation history and compositional effects. Three-phase parameters are estimated on the basis of saturation-weighted interpolation of two-phase parameters. The hysteresis model is an extension of the Land trapping model (Land 1968) but with a dynamic Land coefficient introduced. The trapping model estimates a constantly increasing trapped saturation for intermediate-wetting and nonwetting phases. The hysteresis model overcomes some of the limitations of existing three-phase hysteresis models for nonwater-wet rocks and mitigates the complexity associated with commonly applied models in numerical simulators. The relative permeability model is validated by use of multicyclic three-phase water-alternating-gas experimental data for nonwater-wet rocks. Numerical simulations of a carbonate reservoir with and without hysteresis were used to assess the effect of the saturation direction and saturation path on gas entrapment and oil recovery.