Severe Slugging Control Methods Used in Offshore Multiphase Riser

Severe slugging control in offshore riser is an important aspect of flow assurance, if not well controlled, normal production could be interrupted and jeopardized. In this paper, firstly mitigation methods for severe slugging used in different oilfields are investigated, and their pros&cons, on-site applications and application scope are summarized. Then three severe slugging control methods adopted by CNOOC are introduced, respectively GLCC separation, auto choking, as well as gas lift. GLCC combined with the original slug catcher has solved the slug problem of the QK17-2 Oilfield, saving a lot of space and money. A set of online monitoring and auto-choking system was successfully installed and applied in WC Oilfield, contributing a lot to the production stability and production rate. The delicately designed gas lift annulus and gas injection system are expected to mitigate severe slugging and boost production of a west Africa deepwater oilfield co-explored by CNOOC. The introduction of these on-site cases will be of some value to for future design and analysis of severe slugging control for oil and gas fields.