Multiphase pipelines are increasingly used in oil and gas production systems for tie in of marginal fields to existing processing facilities. For some systems the available pressure is lower than necessary to transport the fluids economically, or to meet the requirements on downstream processing facilities. To overcome such pressure limitation, several pressure boosting options are available, and the use of drag reducing additives (DRA) can in some cases be an optimal solution. The most widely used DRA's are high molecular weight polymeric chemicals designed to reduce the frictional drag for different applications. These chemicals are liquid soluble and affects the frictional losses between the liquid and wetted surfaces at turbulent conditions. A total of 5 datasets with use of drag reducing additives (DRA) in a 14'' offshore multiphase pipeline are presented. Based on these data and a consequent pipeline analysis, the following conclusions are drawn: 1) Injection of DRA gave a significant reduction in total pressure drop for the multiphase pipeline operated at stratified conditions. 2) For a superficial gas velocity of 2.1 m/s and a superficial liquid velocity of 1.8 m/s, the maximum effectiveness of DRA is higher than 50 %. 3) For high concentrations of DRA, the effectiveness reaches an asymptotic value. 4) With decreased superficial liquid velocity and increased superficial gas velocity in combination with increased water cut, the DRA effect is reduced. 5) The different field data show relatively good agreement. 6) For gas/oil ratio (GOR) less than 200 the particular pipeline capacity can be increased by approximately 10 % with use of DRA at high concentration.
Drag reduction in an offshore multiphase pipeline
Multiphase Production Technology '05, 12 ; 585-599
2005
15 Seiten, 9 Bilder, 6 Tabellen, 10 Quellen
Aufsatz (Konferenz)
Englisch
Advances in multiphase operations offshore
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