Effect of Wettability on High-Velocity Coefficient in Two-Phase Gas/Liquid Flow

Abstract

Abstract Gas well productivity is affected by two distinct mechanisms: (1) liquid blocking, and (2) high velocity flow in two-phase. The former has been studied extensively recently but the understanding of the latter is limited. High velocity gas flow in single phase has been thoroughly studied by a large number of authors. Despite the fact that high-velocity coefficient in the presence of an immobile and a mobile liquid phase is much higher than that in single phase, only a handful of studies have been carried on the subject. In this work, we have measured the high-velocity coefficient, β in two-phase gas-liquid flow. The results are presented as a function of liquid relative permeability and also liquid saturation. In our measurements, the wetting state is varied by the treatment with a fluorochemical compound. Then the effect of wettability on the high-velocity coefficient in two-phase flow is investigated. Results show that when the liquid is strongly wetting, the high-velocity coefficient increases some 270-fold in water-gas two-phase flow. However, our data show a systematic reduction of high-velocity coefficients for the altered wetting state in two-phase flow. We present measurements of the velocity coefficients in single-phase flow, and in two-phase flow for both oil-gas and water-gas flow for strong liquidwetting and altered-wetting states. Based on our measurements, we conclude that the treatment of the wellbore region can result in significant improvement in well deliverability from the large reduction of high-velocity coefficients.