cycle stage 2 slug formation u2014 the liquid continues to build up in the riser as a liquid slug pressure builds up behind this liquid slug as gas continues to flow into the pipeline stage 3 slug production u2014 once the liquid reaches the top of the riser the hydrostatic head can no longer increase and therefore gas pressure overcomes the liquid head and a liquid slug starts to be produced stage 4 blowout u2014 once the tail of the slug reaches the base of the riser the gas breaks through and into the riser expanding to cause a violent acceleration of the liquid slug after which some liquid falls back down the riser and blocks the riser base thus commencing the next cycle stage 1 the main issues associated with production whilst in the severe slugging regime occur due to flooding of the separation systems during the slug production phase of the cycle resulting in poor separation and over pressurisation during the slug blow out stage which can cause the platform to shut down completely for example export compressors go into surge mode due to significant variation in the gas flowrates imposing stress on the shaft bearings and operational control issues sometimes this leads to unwanted flaring of the gas furthermore cyclic surges introduce vibration to the process piping system and mechanical fatigue to the riser leading to possible earlier failure accordingly it is important that this flow regime can be controlled or mitigated severe slugging can be managed by making use of slug catchers on the topside facilities but these are generally large vessels designed to hold.