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Statoil Tordis SSBI project

Tordis Subsea Scenario

Norway, Tampen Block 34/7

Landmark: The world’s first full-scale commercial subsea separation, boosting and injection system.

FMC Technologies has delivered a full-scale separation facility to enable re-injection of bulk water into a non-hydrocarbon reservoir (Utsira) and route hydrocarbons through a multiphase pump back to Gullfaks C.
The Subsea processing System including boosting pumps has been designed to handle high amounts of sand (50-500 kg per day) with its sand management system. Along with other upgrades to the field infrastructure, the recovery factor for the Tordis field is expected to increase from 49 percent to 55 percent (approximately 35 million barrels).

The PLIM was installed during the field shutdown summer 2006. The water injection tree was installed early 2007, and the subsea separation, boosting and injection system summer 2007.
Tordis Subsea Separation, Boosting and injection station is now onstream.

 

System Description:

Pipeline Inline Manifold (PLIM)

The PLIM was installed summer 2006 to interconnect the flowlines from the existing Tordis Subsea Manifold to the Gullfaks C platform, allowing rerouting of the Tordis well stream to Gullfaks C via the PLIM.

The PLIM allows full bypass of the Tordis Subsea Separation station, and was installed during a planned maintenance shutdown of the Gullfaks C Platform.

Water Injection Tree

The Water Injection Tree is a simple Xmas Tree consisting of a 12” ball valve. A conventional internal tree cap is installed in the vertical entry section of the tree, allowing for workover of the well. The reinjected water is pumped through this Xmas Tree through a 13-5/8 casing direct into the Utsira water reservoir. This is a nonhydrocarbon reservoir with ambient pressure.

Subsea Separation, Boosting and Injection (SSBI) Station

The Subsea Separation, Boosting and Injection Station separates the water from the wellstream which is reinjected through the large-bore Water Injection Tree. After separation, gas and oil are mixed and pumped via a multiphase pump back to the Gullfaks C platform. The SSBI Station was installed in October 2007.

 

The Separation Station contains the following main elements:

Foundation Structure and Manifold 
The Tordis SSBI Station has a conventional, overtrawlable foundation structure supporting the manifold, the separator module and all other modules and components. The structure has four suction anchors, one in each corner for foundation and leveling.

The manifold module provides connection to the flowlines via the Rovcon connection system and interconnects the various modules.

Separator Module
The well fluid from the Tordis field is first routed into the separator vessel. The inlet cyclone in the vessel does a first separation where the majority of the gas is separated out and routed through a separate gas bypass line outside of the vessel, thereby minimizing the size of the separation vessel. The remaining water, oil and gas are separated through the gravity principle inside the vessel. The water is the heaviest part, which is pumped via a water injection pump directly back into the Utsira reservoir through the Xmas Tree. Oil and gas are remixed and pumped through a multiphase pump back to the Gullfaks C platform. Any deposit of sand inside the separation tank is handled by the sand removal system.

The Separator Module is retrievable.

Sand Removal System
Any sand from the wellstream will deposit at the bottom of the separation vessel. A flushing system with specially designed nozzles has been developed to flush out the sand at certain intervals. The sand is transported into the Desander Module, and then mixed with the injection water and reinjected into the reservoir downstream of the water injection pump.

Water Injection Pump
The Water Injection Pump is a Framo liquid pump which is driven by an electrical motor powered through an electrical power cable from the Gullfaks C platform. The pump can be retrieved for maintenance by a pump-running tool.

Multiphase Pump
The Multiphase Pump is a Framo multiphase pump, and is powered through an electrical power cable from the Gullfaks C platform. It can also be retrieved by the pump-running tool.

 

Other
The Subsea Separation Station is equipped with two multiphase flowmeters (Roxar) which will measure the composition of the well flow to prepare the separation system settings. A level monitoring system is installed in the separation tank to monitor water, oil and gas interfaces which again provide input to the water pump speed. The Subsea Separation Boosting Injection Station includes one subsea control module to control the various functions of the station and communicate back to the Gullfaks C platform.

 

Main Suppliers:

CDS Engineering (Now 100% FMC Technologies): Separarator Design, Internals in the Separation vessel
Framo Engineering: Water Injection Pump, Multiphase Pump, Topside Electrical Power System
Leffer & CDS (Now 100% FMC Technologies): Separation Vessel and Desander Vessels
ScanRope Subsea Cable: Subsea Electro-Hydraulic Umbilical
NN: Power Cable
Roxar: Multiphase Flowmeters
Grenland Offshore: Fabrication of Foundation Structure, Manifold and Modules
Tracerco: Level Profilers




  • Contract Award: 2005
  • Sales: Kongsberg/Asker, Norway
  • Fabrication Trees: Dunfermline, U.K.
  • Fabrication Controls: Kongsberg, Norway
  • Service Base: Bergen, Norway
  • Contract Type: EPC