Subsea Processing & Pumping Systems 

Hydraulic Submersible Pumps (HSP) are manufactured by Weir Pumps. A large number (17) was delivered by Weir for the Captain Project (to Texaco and Chevron). The pumps are reliable and feature a mean time to failure of 5 years. However, this technology is not seen as a field proven product in comparison to Electrical Submersible Pumps. The power water system was in particular an issue on Captain Project, and such a solution would however only be considered for projects featuring water injection systems.

The depicts a Weir HSP multistage centrifugal / axial pump powered by a multistage, axial flow, liquid driven turbine.

Figure 7.1 - Weir Hydraulic Submersible Pump

The Electrical Submersible Pump (ESP) is a boosting system composed of a pump, a protector and a motor as main elements and which can virtually be installed at any water depth. This "insensibility" to water depth is provided by the protector, which function is to allow the internal pressure of the motor to be balanced with the external pressure without contact between the motor internals and the effluent. The multistage centrifugal pump is connected to the electrical motor though this protector. The motor is cooled by the effluent and fed by an electric cable (e.g. from the wellhead for down-hole ESPs).

The ESP surface equipment features either Variable Speed Drive (VSD) and electrical transformers or switchboard.

Figure 7.2 - ESP Overview

The ESP field proven characteristics are the followings:

Petrobras developed a program in the 90's to allow the installation and operation of subsea well equipped with an ESP. This goal was achieved for the first time in 300m water depth in 1994 and then in deeper waters (1115m) in 1998 on the Albacora field (RJS-477 well).

Figure 7.3 - Installation of ESP on Petrobras RJS-477 well (Albacora)

The ESPs are accepted as a field proven technology and are used by many operators, e.g. on the Total Otter field which was developed with dual ESPs to allow the long tie-back (21km) development. The ESPs are generally used for down-hole applications. One of the drawbacks to their application, particularly in deepwaters, is their need for regular replacement (e.g. typically 2-4 years). The current considered alternatives are to use ESP either in a dummy well, e.g. Petrobras VASPS (Section Section 5.3, “VASPS”) or Jubarte field alternative (see and ) or in a caisson located on the seafloor (which can include gas/liquid separation function). These alternatives would in particular facilitate the interventions and maintenance operations.

Figure 7.4 - Petrobras Jubarte Field (Phase 1) – Downhole or Dummy Well Alternatives of the ESP

Figure 7.5 - Jubarte Field Phase 1 – Dummy Well Selected Location of the ESP (FMC Technologies)

The main ESP manufacturers are: