FMC Technologies has delivered all the commercial subsea separation systems in the industry since the first contract was awarded in 2005. Three of these have included an extensive sand handling system, including:
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Marlim Subsea Separation System, for Petrobras in Brazil
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Pazflor Subsea Separation System (SSS), for Total in Angola
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Tordis Subsea Separation Boosting and Injection (SSBI) system, for Statoil in the North Sea
Marlim Subsea Separation System
The Marlim system is the most complex subsea processing project executed to date. The water is separated from the well-stream and re-injected back into the reservoir. This is the first application where the produced water is used for pressure maintenance of the reservoir as part of the subsea separation operation and also the first subsea heavy oil application.
The system includes a PipeSeparator concept for the separation of the water from the well stream, and a water treatment system using InLine HydroCyclones. The sand handling system includes an InLine DeSander at the inlet of the separation system. The purpose of this is to remove the majority of the sand, from the multiphase well stream, to protect the downstream equipment and to avoid sand accumulation. It also contains a dual redundant Sand Jetting System in the outlet section of the PipeSeparator, and an InLine DeSander for removal of the smallest particles in the water stream from the separator to protect the re-injection well and reservoir. The separated sand is routed with the oil up to the topside facility.
All the separation and sand handling equipment have been tested as part of the technology qualification program started 4Q 2009, and completed 2Q2010.
Pazflor Subsea Separation System
The Pazflor system is a subsea gas liquid separation and liquid boosting system. The purpose of the separator is to remove the gas from the liquid, such that the liquid can be pumped while gas flows free to the surface. The Pazflor project includes three subsea separation stations, each including one separator and two hybrid boosting pumps.
The separator is designed to ensure no sand accumulation. In addition, a sand handling system including a proprietary sand flushing arrangement is installed as a back-up solution to remove any build-up of sand during operation.
The sand handling was qualified as part of the Technology Qualification Program during an extensive separation and sand handling qualification program in 2008.
Tordis Subsea Separation Boosting and Injection
The Tordis system is a water and sand separation and re-injection system. The water and sand are separated from the well-stream in a semi-compact separator vessel, where the sand separates and accumulates at the bottom. The vessel includes a sand removal system which is operated by high pressure water from the water injection pump. This system is a dual redundant system with two independent technologies:
The removed sand is transported to a desander and sand accumulator vessel in batches. The accumulated sand is pressurized and transported to the discharge side of the water injection pump. All the separated sand is injected with the water. The sand handling system ensures that the water injection pump will not see significant amounts of sand.
The sand handling system applied for Tordis was qualified through a Subsea Separation and Sand Handling System qualification program executed at FMC’s facilities in the Netherlands during 2003 and 2004. The InLine DeSander/sand accumulator was qualified as part of the Technology Qualification Program of the Tordis project in 2005.