Experimental investigation and simulation of severe slugging in pipeline-riser system

From the observations of severe slugging carried out on a laboratory facility, it was found that the flow pattern of gas-liquid flow behind the Taylor bubble front in the riser at the bubble penetration stage was slug flow, and the churn flow existed in the riser at the gas blowout stage. Based on these observations, a new theoretical model was developed to predict the characteristics of gas-liquid flow in the pipeline-riser system, in which the two-phase flow behavior in the riser was predicted by a drift-flux model, and the mass conservation of gas in the pipeline and the momentum conservation of the liquid between the Taylor bubble front and the top of the riser was considered. Compared to the experimental results, it was verified that the present model predicted accurately the process of gas flow in the pipeline and riser and the system variables such as pressure transients, cycle time, liquid slug length and liquid accumulation.