Design and Verification Testing Of Balance Piston for High-Viscosity Multiphase Pumps

Abstract

OneSubsea was awarded a project involving the development and testing of a HighBoost multiphase pump for boosting unprocessed multiphase well streams with liquid viscosities up to 800 centipoise (cP). The viscosity requirement surpasses the existing viscosity range of dynamic multiphase pumps and the difference in viscosity for the liquid and gaseous phases is larger than in any other comparable test programs. Results from the full-scale testing have shown remarkable balance piston flow mechanisms affecting both rotordynamic behavior and step-changes in volumetric efficiency for the pump assembly. These phenomena have been studied in detail during the extensive testing, and further investigated with corresponding analysis. The work described in this paper has resulted in a design improvement and a solution for this demanding subsea boosting application. Furthermore, the analysis also shows that more research is needed to fully understand high viscosity multiphase flow in seals and balance pistons. The comprehensive technology development work was conducted within the EPC project timeframe and has realized the operators requirements of boosting the subsea production of a demanding oil-field.