25. Influence of Liquid Viscosity on Horizontal Two-Phase Slug Flow

Slug flow is present in many industrial processes, including the ones related to the petroleum industry. Such flow pattern is characterized by the intermittent repetition of liquid slugs that may or may not be aerated and elongated bubbles that flow atop a liquid film. Most of the existing models for slug flow have been developed for two-phase water-air flows, but in oil and gas production, the liquid phase can be substantially more viscous than water. This article aims to evaluate the effect of liquid viscosity increase on slug flow parameters, such as bubble velocity and frequency. An experimental study on liquid-gas flows in a 26 mm ID and the 8.65 m long horizontal pipe was developed to achieve this goal. Water and mixtures of water and glycerin with a viscosity of 5.46, 10.27, 15.39, 20.33, and 30.37 cP comprise the working liquids. The slug flow parameters were measured by a resistivity sensor located at one measuring station. Results show that the increase in the viscosity of the liquid results in an increase in the velocity of the elongated bubble. The effects on the slug frequency depend on the superficial velocities of the fluids.