Page 57: of Offshore Engineer Magazine (Jul/Aug 2013)

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retroft solution is required to maintain

Subsea reservoir pressure and stabilize crude oil production.

Petrobras’ Albacora feld in the

Campos basin had this problem. As a mature, giant feld in water depths of 250-1100m, it has seen much develop- ment. The original FPSO, P. P. Morales, was installed in 1987, followed by

FPS semisubmersible P-24 in 1993 in a second development phase. In 1996, the P-24 was replaced by two units: the FPS semi P-25 was installed frst, followed two years later by the FPSO

P-31 in 1998. Field production peaked in 1999, and the reservoir required more pressure support than the exist- ing water injection system could deliver.

The company created a research project to solve the problem, facing the issues of water properties, reservoir compatibility, equipment reliability, power delivery, corrosion, and biologic control. In addition, new infll drilling was planned for the feld, which would increase the need for water injection at higher fow rates. SWRI was the most economic solution, rather than adding conventional topside capacity, replac- ing the existing FPS, or adding a new

FPS.

The SWRI system includes a buoy to support water intake at about 100m above the seabed, where water qual- ity is best; a skid with variable-speed controllers, fltration, and pumps that sits on the seabed; and related power cable, fowlines, jumpers, etc. The subsea system is connected to the P-25 topside facility for delivery of biocide and related chemicals.

The system began operating October 2012. Water injection will ramp up as needed to a maximum 16,500cu m/d into seven injection wells.

Helico-axial multiphase pump

Petrobras has had diffculty fnding helico-axial multiphase pumps (HMPP) to meet its need for high differential pressure to move viscous crudes. The gas-lift systems it uses can handle pressures around 45 bar (652psi), which is similar to the limit on many

HMPPs. However, the company has

The frst subsea multiphase pump was felds that require stronger equipment. installed by Shell at Draugen feld in

The company initiated a research

Block 6407/9 in the Norwegian Sea. program in cooperation with FRAMO, oedigital.com July 2013 | OE 59 subsea.indd 59 6/25/13 12:45 AM