A Mechanistic Slug-Liquid-Holdup Model for Different Oil Viscosities and Pipe-Inclination Angles

Abstract

Summary Slug liquid holdup is one of the most important parameters of slug flow. It is closely related to the average liquid holdup and pressure gradient of slug flow in wells and pipelines. The mechanistic models of Barnea and Brauner (1985) and of Zhang et al. (2003a) are based on the turbulent liquid-slug assumption for low-viscosity oils. However, for high-viscosity oil, the liquid slug is laminar because of the low slug Reynolds number. In this study, a mechanistic slug-liquid-holdup model is developed for low- and high-oil-viscosity slug flows. The model is based on two shear mixings: shear mixing between the slug front and pipe wall and shear mixing between the slug body and liquid film. The model uses slug-flow characteristics that can be calculated by solving the continuity and momentum equations of slug flow. A data bank consisting of 418 slug-liquid-holdup measurements that were obtained from various authors is used to analyze and validate the model. In the data bank, liquid viscosity ranges from 0.0016 to 0.589 Pa·s (1.6 to 589 cp). Pipe-inclination angle ranges from −30° to upward vertical. Pipe inside diameter varies from 5.08 to 10 cm. Statistical evaluations are conducted and compared with predictions of other models, and significant improvement is observed in the performance of the new model.