A review on mechanisms and models for the churn-turbulent flow regime

Eulerian–Eulerian Modeling of Multiphase Flow in Horizontal Annuli: Current Limitations and Challenges

Multiphase flows are present in many natural phenomena, processing technologies, and industries. In the petroleum industry, the multiphase flow is highly relevant, and special attention is paid to the development of predictive tools that determine flow conditions to guarantee safe and economic hydrocarbon extraction and transportation. Hydrodynamic aspects such as pressure drop and holdup are of primary relevance for the field engineer in daily operations like pumping power calculation and equipment selection and control. Multiphase flow associated with oil production is usually a mixture of liquids and gas. The hydrodynamic behavior has been studied in different pipeline configurations (i.e., vertical ascending/descending and horizontal/inclined pipelines). However, the available information about flow patterns as well as the general conditions present in horizontal annuli is incomplete, even if they are of fundamental relevance in today’s horizontal drilling, production, and well intervention in many oil wells around the world. This review aims to present an in-depth revision of the existing models developed to predict two-phase flow patterns and hydrodynamic conditions in annuli flow, focusing mainly on, but not limited to, horizontal configuration. Key flow parameters and effects caused by annuli geometry and the physical properties of fluids are extensively discussed in the present paper. Different empirical correlations and mechanistic and numerical models on two-phase flow through horizontal/inclined pipelines and in both concentric and eccentric annuli are analyzed. Some of these models partially agree with experimental results and show acceptable predictions of frictional pressure loss and flow patterns. Limitations in current models and challenges to be faced in the next generation of models are also discussed.

Engineering Simulation Tests on Multiphase Flow in Middle- and High-Yield Slanted Well Bores

Previous multiphase pipe flow tests have mainly been conducted in horizontal and vertical pipes, with few tests conducted on multiphase pipe flow under different inclined angles. In this study, in light of mid–high yield and highly deviated wells in the Middle East and on the basis of existent multiphase flow pressure research on well bores, multiphase pipe flow tests were conducted under different inclined angles, liquid rates, and gas rates. A pressure prediction model based on Mukherjee model, but with new coefficients and higher accuracy for well bores in the study block, was obtained. It was verified that the newly built pressure drawdown prediction model tallies better with experimental data, with an error of only 11.3%. The effect of inclination, output, and gas rate on the flow pattern, liquid holdup, and friction in the course of multiphase flow were analyzed comprehensively, and six kinds of classical flow regime maps were verified with this model. The results showed that for annular and slug flow, the Mukherjee flow pattern map had a higher accuracy of 100% and 80–100%, respectively. For transition flow, Duns and Ros flow pattern map had a higher accuracy of 46–66%.