Two-Phase Slug Flow Correlations for Severe Slugging in Subsea Pipelines

Abstract

Slug flows in multiphase petroleum fluids may present substantial challenges to the economical and safe operation of equipment used for oil recovery, flow separation and stabilization. Two-phase slug flow parameters provide key information in the design of downstream separation installation, particularly in slug dominated flows. In this paper, a dimensionless analysis based on the Buckingham pi theorem will be used to develop and analyze new slug velocity correlations. The empirical model uses relevant dimensionless numbers including the Reynolds number, Bejan number, and the density ratio. The new model can be used in the selection of operating conditions and secondary recovery mechanisms. Over 5,000 data points were used for the analysis, covering choke openings between 10 and 100 percent, and Reynolds numbers between 150 and 400. The dimensionless numbers in the correlations show the dependence of the slug velocity on differential pressure, choke valve opening, and mixture flowrate. The correlation predicts 90% of the measurements within a 10% maximum percentage error. The mean absolute deviation of the correlation is about 9%. The model can be applied for low flow rates typical of some flow conditions in subsea pipelines, and choke openings between 10-98%. The correlation can predict the slug velocity and production rates for vertical and catenary riser systems. Keywordssubsea pipelines; severe slugging; dimensionless analysis; two phase flow; oil recovery.