Pressure wave propagation characteristics and two-phase pressure drop in a long-distance pipeline-riser system

To ensure the flow safety of the offshore gathering pipeline system, it is critical to study the large-scale pressure wave propagation behavior and predict the two-phase pressure drop in the subsea pipeline. In this paper, the local flow structure, pressure wave propagation characteristics, and two-phase pressure drop of the horizontal pipeline are obtained in a long-distance pipeline S-shaped riser system with a diameter of 46 mm and a total length of 1722 m. The overall-local correlation flow pattern map in the pipeline-riser system is proposed. The propagation modes of the pressure wave induced by the riser's pressure fluctuation in the horizontal pipeline under different overall flow patterns are clarified, and the correlations for predicting the propagation velocity and the attenuation coefficient of the pressure wave are proposed. The correlation for predicting the two-phase pressure drop of long-distance horizontal pipeline in the pipeline-riser system is established, and 88.23% of the data are within the error interval of ± 10%.