Mixing Performance and Three-Phase Flow Characteristics in Continuous Cement Slurry Mixing Systems

Summary To meet the performance regulation requirements of special gas-containing cement slurries for cementing operations under complex working conditions, such as deep wells and shale gas wells, and to address the problems of difficult precise control of gas holdup and unclear regulation mechanism in existing technologies, we systematically investigated the influence laws of key parameters on slurry gas holdup during the mixing process of special gas-containing cement slurries in the continuous cement slurry mixing system based on the computational fluid dynamics (CFD) method. By integrating the Eulerian multiphase model, standard k-ε turbulence model, and multiple reference frame (MRF) approach, we developed a novel numerical simulation method for gas/liquid/solid three-phase flow and established a corresponding CFD model. Parallel three-phase flow experiments confirmed the model’s reliability, as it demonstrated accurate gas content prediction (error < 5%). Using this validated model, we conducted a comprehensive analysis of the evolution characteristics of slurry gas content during the mixing process, and elucidated the underlying mechanisms through a multidimensional analysis. Parametric studies quantitatively evaluated the effects of various structural parameters under standard operating conditions. Key findings include (1) significant positive correlations between gas content and both impeller diameter (700–1,000 mm, K = 0.00875 mm⁻¹) and rotation speed (150–400 rev/min, K = 0.00028 rev/min⁻¹); (2) a linear relationship between gas injection rate (<0.03 kg/s) and gas content; and (3) notable impacts of nozzle configuration (width 20–80 mm, inclination 0–50°) and positioning (optimal above the impeller) on gas distribution. The proposed multiphase coupling simulation approach provides a new technical tool for optimizing cement mixing system design. These results establish a theoretical foundation for parameter optimization in specialty cement slurry preparation and offer practical guidance for precise gas content control through impeller design adjustment, gas flow regulation, and nozzle configuration.