Experimental study of severe slugging in pipeline-riser system

The severe slugging was studied in a laboratory facility which simulated deepwater pipeline-riser systems. The test pipeline consisted of a 114 m horizontal section and a 19 m downward inclination section which had different slopes. The flow pattern maps of different slopes were presented. It was found that the severe slugging occurred when the slope of the downward pipe section was zero. Distinct instabilities were observed in severe slugging and the flow characteristics fluctuated periodically. The pressure had large fluctuation magnitude. The liquid and gas flowed out of the system intermittently. A long liquid slug appeared in every cycle and moves into the downstream separator with very high velocity. The relation between the period of severe slugging and gas or liquid flow rates was analyzed and it can be regressed by a power law correlation.