Abstract

PETROBRAS, other operators and suppliers have carried out many efforts to make available the subsea multiphase pump technologies. Many of these pumps were installed and are now in operation, including helico-axial pumps. However, until now, these pumping systems were limited to differential pressures lower than 45 bar, which is not attractive to PETROBRAS scenarios, since the gas-lift has similar performance. Thus, PETROBRAS launched a program to qualify, through flow loop tests and field operation, a helico-axial multiphase pump to differential pressures up to 60 bar. The Barracuda field was selected to host the prototype. This paper describes the Barracuda helico-axial multiphase pump, including the design phase, qualification process and operational experience so far, involving: installation, commissioning and operation.

The Barracuda multiphase pump is designed to operate at maximum differential pressure of 70 bar. The other main flow characteristics are: liquid flow rates between 2000 and 3000 m3/day; GVF between 35 and 60%; and viscosity between 15 cP and 20 cP. The pump is installed at a water depth of 1040 meters and distant 10,5 Km from the P-48 production platform. The boosting system is composed by many components, including a flow base, control system, topside equipments, integrated umbilical and subsea motor-pump unit inside the pump module. This boosting system was comissioned in July of 2012 and since then its operational performance has been evaluated.

A description of the main subsystems of the Barracuda Multiphase pump is presented, including their qualification process and FAT tests. In order to evaluate the hydraulic performance of the motor-pump unit, a special flow loop test program was established. The results of this qualification process and the operational experience indicated that this technology is adequate to be applied in other similar applications.

Boosting untreated oil is a field proven solution and is coming to the age. Efforts to develop high differential pressures multiphase pumps will increase its operational envelop, that will enable its use in important scenarios, accelerating the number of applications and increasing the benefits of this important subsea boosting method. The benefits to brown and green fields will be significant, mainly to Campos Basin scenarios.

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