Abstract: A method of controlling occurrence of slugging in a riser of a pipeline arrangement including a riser base and pipeline conveying a multiphase fluid system in which the gas phase may be natural gas. The upper end of riser is connected to a separator vessel. The gas phase of the multiphase fluid system is separated from the liquid phase so that the separated gas leaves through gas outlet pipe controlled by a first valve, and the liquid leaves through an outlet pipe controlled by a first valve. The first valve regulates the velocity of gas along the pipeline towards the riser. A pressure sensor observes the gas pressure in the riser base, and if the observed pressure exceeds a predetermined control pressure value a three term pressure indication control causes the first valve to be operated to pen to an extent that increases the gas outflow through the pipe, and thus increases the velocity of gas in the pipeline to avoid occurrence of severe slugging in the riser.

Abstract: A method of controlling occurrence of severe slugging in a riser (6) of a pipeline arrangement (2) comprising a riser base (8) and pipeline (4) conveying a multiphase fluid system in which the gas phase may be natural gas. The upper end of riser (6) is connected to a separator vessel (10) wherein the gas phase of the multiphase fluid system is separated from the liquid phase so that the separated gas leaves through gas outlet pipe (12) controlled by a valve (14), and the liquid leaves through an outlet pipe (16) controlled by valve (18). The valve (14) regulates the velocity of gas along the pipeline towards the riser.