Heavy slugging was observed in a well-pipeline-riser system connected to the Statoil operated Åsgard A production ship offshore Norway. Large variations in pressure, temperature and rates both in the well, the pipeline and in the topside processing facilities caused several problems. Downhole pressure variations concerned the reservoir engineers while temperature variations in the pipeline gave concerns related to hydrate formation. An effective project organisation was formed to find a solution promptly. Control engineers, reservoir engineers, process engineers as well as control room operators had to work effectively together, and difficulties between land and offshore based organisations must be overcome. The concept of Integrated Operations forms a basis for streamlining work processes across disciplines both onshore and offshore. The slug control project presented was conducted according to the philosophy of Integrated Operations. This was possible by utilizing the real-time Onshore Support Centre for the Halten Nordland area. Costs were saved by avoiding offshore trips for land based personnel, and creative solutions to unforeseen problems were formed.
The technical solution to the problem is presented. The heavy slugging was effectively removed by an automatic slug control system based on feedback from the well pressure. The implemented solution opens up for increased production and recovery, since it is possible to produce close to actual constraints, for example bubble point pressure, max sand free rate and hydrate temperature.
