Sand deposition characteristics and critical velocity prediction model in shale oil gathering pipeline

Abstract Sand deposition in shale oil gathering pipelines poses risks including flow area reduction and accelerated internal corrosion. Precise prediction of the critical velocity is essential to ensure pipeline system integrity. Utilizing a 15‐m long experimental pipeline with 50‐mm internal diameter, we conducted multiphase sand transport experiments under varying gas–liquid velocities, sand particle sizes, concentrations, and pipe inclinations, establishing quantitative correlations between multiphase sand transport patterns and critical velocity thresholds. Six characteristic sand transport regimes were identified: suspended, heterogeneous suspension, moving bed, moving dunes, stationary dunes, and stationary bed. Particle dynamics analysis revealed a dual‐mechanism transition: turbulent fluctuations sustain particle suspension, while liquid drag provides translational momentum. Sand particle size, concentration, and pipe inclination collectively influence sand‐carrying capacity by modifying particle dynamics and multiphase flow characteristics, all exhibiting positive correlations with critical velocity, whereas liquid viscosity shows a negative correlation. The proposed model integrates particle clustering dynamics and inclination modifications into the Archibong framework. When coupled with the Xiao model it achieves 8.14% prediction error. This study established the sand transport characteristics shale oil gathering pipelines and the prediction method of critical velocity, which provided theoretical basis and methodological support for the optimal operation of the pipeline system and sand control.