Deepwater Multiphase Pumping System With High Flow-Rates And Long Tie-Back Distance

Further to the successful completion of the long term underwater operations at the ENI-Agip Prezioso Field, ENI-Agip Div. and Saipem Group have undertaken a new R&D project on multiphase transportation and boosting technologies called "Deepwater Multiphase Production & Transportation Systems", with the contribution of Nuovo Pignone as multiphase boosting pump manufacturer. A qualification programme for an high flow-rate multiphase boosting unit has been foreseen, considering the aspects of the high flow-rate boosting, the packaging and the long step-out distances feeding of a subsea unit suitable for deepwater application. The subsea pump is based on the twin counter rotating screws concept, developed by Nuovo Pignone. This unit is able to handle the whole multiphase fluid production coming from a multi well field configuration; it is positioned downstream the production manifold at a water depth of about 1000 m and 30 Km far from the topside facilities. The paper presents the results of the basic design of the subsea system, the configuration of the main equipment, the history of previous pumping systems built and qualified, the construction of the new prototypes and the first test results on the test loop in Nuovo Pignone factory.