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1TUV/NEL Produced Water Club 23rd April 2010
Subsea Produced Water Treatment : Challenges and Solutions for
Deepwater
TUV/NEL Produced Water ClubAberdeen, 23rd April 2010
Wayne Evans – VEOLIA WATER
2TUV/NEL Produced Water Club 23rd April 2010
Agenda
• Applications and needs
• Challenges to go further and deeper
• Saipem / Veolia agreement Principles and objectives for subsea development
• Development work on goingFirst separation stage Produced water treatment
• Conclusion
3TUV/NEL Produced Water Club 23rd April 2010
• Subsea liquid / liquid separation and produced water treatment:• Subsea Separation of water • Subsea water reinjection• Export of oil and gas to surface
Need for water treatment depending on quality required for injection
Principles
To FPSO
4TUV/NEL Produced Water Club 23rd April 2010
Typical production profile
020406080
100120140160180200
0 5 10 15 20
Years
Kbp
d
OIL
WATER
LIQUID
• Mature fields• Topsides debottlenecking of water treatment capacity for additional
satellite fields development• Increase recovery
• New fields:• Increase recovery • Reduce cost
Subsea liquid / liquid separation applications
More water produced than oil
5TUV/NEL Produced Water Club 23rd April 2010
Mature field applications
• Troll Pilot – N. Hydro (June 2000)Water re-injection in a disposal wellTotal liquids: 60 000 blpdWater depth: 340 m
• Tordis – Statoil (Sept. 2007)Water & sand re-injection in a disposal wellIncreased recovery factor from 49% to 55%26 million bbl extra oilWater depth: 210 m
• Next to come: Marlim – Petrobras (2011)Water reinjected in injection wellWater depth: 900 m
State of the art
Station size: 17x17x8 m
6TUV/NEL Produced Water Club 23rd April 2010
Challenges to go further and deeper
• Challenges:• Water depth
Manufacturing of heavy wall pressure vesselsWeight of components (for maintenance with light intervention vessels)
• Water quality required when re-injected into the reservoirComplexity / reliability of advanced process and associated operating modesControlSensorsMaintenance requirements
=> Need efficient and reliable process to guarantee water quality
The development of such subsea systems requires the association of :• water treatment expertise • subsea system capability
7TUV/NEL Produced Water Club 23rd April 2010
Partnership
SAIPEM and VEOLIA PARTNERSHIP
Agreement signed in 2009 between Saipem and Veolia to develop subsea water treatment systems, combining:
Saipem experience and expertise in subsea systems, deepwater technologies, system integration, qualification testing, etc.
Veolia experience and expertise in water processing offshore, equipment design, supply and operation with a long track record
8TUV/NEL Produced Water Club 23rd April 2010
Saipem expertise for subsea process
Experience in very large EPCI deepwater projects: Rosa, Kizomba A & B, Akpo, Usan, …
Since the 90’s:Technology developments in several subsea process areas …
… boosting, gas-liquid separation and liquid-liquid separation, with a focus on deepwater applications.
Multipipe gas/liquid separator
Subsea process from a deepwater perspective
9TUV/NEL Produced Water Club 23rd April 2010
Veolia water treatment expertise
• Packaged Plant:Seawater treatmentProduced water treatment
• Topsides water treatment modules:
Golfinho II modules delivered to Saipem
10TUV/NEL Produced Water Club 23rd April 2010
Saipem / Veolia subsea development
• Objectives:• Development of flexible solutions to subsea water processing to free
operators of the restrictions inherent in current subsea technologies
• Offer solutions to suit the water treatment requirements instead of specifying water quality to meet the capability of the available equipment
• Process • Start from general cases to screen solutions, identify development
needs and propose solutions compliant with deepwater requirements
11TUV/NEL Produced Water Club 23rd April 2010
Investigated solutions and technologies
First separation stageGravity separator/ 3C cyclone
Water treatment
Stage 1Hydrocyclone
Water treatment
Stage 2Flotation
Water treatmentCeramic membranes
To injection wells To injection wells
Inlet
Oil in water
1000 to 2000 ppm
Oil in water 100 ppm
Oil in water 20 ppm
Solid in water 15 ppm
Typical performances
12TUV/NEL Produced Water Club 23rd April 2010
First stage – Separation
• Key drivers: • Produced water treatment: required for high water quality => more sophisticated
process• First separation stage should provide water treatment with required water quality
=> Need for robust and flexible first separation stage
• With high performance first separation stage water treatment stage will be more efficient and reliable
• Investigated technologies:• Gravity separation
Conventional process solution for liquid/liquid separationRobust and reliable
• Cyclonic separationInnovative solutionCompact Efficient
13TUV/NEL Produced Water Club 23rd April 2010
First separation stage Horizontal Gravity Separator
• Designed for ~ 90 kbpd• 1500 m wd
• 3 min residence time• 8 m3 Slug Capacity
• ID: 2.5 m• Ltt: 12.8 m• Wall thick.: 90 mm
• 120 tons empty in air• ~ 0 empty in water • 110 tons in operation
subsea• Additional internal could be used if required • Sand jetting system required• Level sensors for water and oil interfaces monitoring
Robust design but space and weight consuming
14TUV/NEL Produced Water Club 23rd April 2010
First separation stage3C cyclone development
• On going development by Saipem for liquid/liquid separation:3C cyclone (patented)
• Developed to be compatible with subsea application:
Specific cyclone design (plate) coupled with Pressure Regulating Vessel (PRV)
FlexibleLimited control Compact Efficient
• Keys for qualification:• Separation efficiency• Control principle
• Development work:• CFD simulation for design optimization• Control simulation• First qualification tests (2 phases)
90 mm
300 mm
15TUV/NEL Produced Water Club 23rd April 2010
First separation stage3C cyclone - Principle
3C Cyclones PRV
Gas/liquid separation
Water treatment
Light outflow (oil)
Heavy outflow (water)
Gas
To injection well
Preliminary separation
Liquid/liquid separation
Produced water treatment
To surface
Inlet
Subsea separation station
Oil
Liquid
Saipem
16TUV/NEL Produced Water Club 23rd April 2010
First separation stage3C cyclone – Qualification
• Qualification tests• Prototype : Cyclone and PRV
PlexiglasScale 1 cyclone
• Test loop:Instrumentation:
– P & T sensors – Flowmeters– Malvern (oil droplets measurement)– Camera for macro pictures
3 sampling points for separation performance survey
Fluids:– 2 synthetic oils (2 viscosities)– water
17TUV/NEL Produced Water Club 23rd April 2010
First separation stage3C cyclone
• Efficient separation performance • 17 µm cut off at turndown conditions
• Simplified control:• Flexible regarding
Inlet flowrateInlet water cut
• Single valve required at 3C water outlet, infrequently actuated
• Way forward:• Definition of preliminary gas/liquid separation stage • Optimization of PRV arrangement • Definition of next qualification phase (real crude?)
18TUV/NEL Produced Water Club 23rd April 2010
Investigated solutions and technologies
First separation stageGravity separator/ 3C cyclone
Water treatment
Stage 1Hydrocyclone
Water treatment
Stage 2Flotation
Water treatmentCeramic membranes
To injection wells To injection wells
Inlet
Oil in water
1000 to 2000 ppm
Oil in water 100 ppm
Oil in water 20 ppm
Solid in water 15 ppm
Typical performances
19TUV/NEL Produced Water Club 23rd April 2010
Produced water treatment
Water processing options• First the sand must be removed:
• Desanding hydrocyclones
• Then oil removal is required:• Deoiling hydrocyclones for bulk oil removal• Flotation for residual oil removal
• Or we remove the oil and residual solids together:• Ceramic membranes
20TUV/NEL Produced Water Club 23rd April 2010
Produced water treatment - Desanding
Desanding Hydrocyclones• Sand separation and handling critical to any
subsea water treatment system• High pressure wellhead systems already
operational – no difficulty in marinization
• Subsea challenges:TurndownSand settlingSeparator jetting
• Solutions:Eductor technology already availableSolids returned to export line to avoid localised discharge
21TUV/NEL Produced Water Club 23rd April 2010
Produced water treatmentDeoiling Hydrocyclone
Status• Hydrocyclone technology is well
understood with high reliability for subsea operations
• Challenges:Hydrocyclones do not respond well to turndownContinuous adjustment of reject impossible without control valve
• Solutions:Pressure balanced system maintains best practicable operationReduced efficiency counteracted by flotation unit downstream
22TUV/NEL Produced Water Club 23rd April 2010
Subsea Flotation Unit
Status• Based on CoPhaseTM CFU.• Self-adjusting flotation unit with no
external power or gas requirement and no recirculation pumps
• Challenges:Eductors to be redesigned for high pressure operation followed by high pressure testingLevel/pressure control valves unavailable
• Solutions:Pressure balanced system maintains best practicable operation
23TUV/NEL Produced Water Club 23rd April 2010
Produced water treatmentMembranes
• Reinjection below fracture pressure requires removal of emulsified oil (<20 micron droplets) and fine solids (<1 micron particles)
• In order to go below 20 microns oil and solids treatment, we need something different:
• Ceramem® ceramic membranes being adopted topsides:
Will separate highly emulsified oilsRemove all solids > 0.1 micronTolerant of high inlet solidsSuitable for high temperature operationEasily cleaned
• However: topsides performance still not predictable
24TUV/NEL Produced Water Club 23rd April 2010
Ceramic membranes
• Challenges:• Improve predictability of membrane fouling
performance. (Characterisation programme underway)
• Hyperbaric membrane testing required (no problems envisaged)
• Backflushing and cleaning solutions needed (conceptual design complete)
• Chemical storage solutions required (conceptual design well advanced)
• Subsea controls for batch cleaning operations (solutions available)
• Online monitoring of very low quantities of solids and oil
CIP
MembranesFeed
Concentrate
Permeate
25TUV/NEL Produced Water Club 23rd April 2010
Subsea station integration
• Integration of all equipment in subsea station:• Challenge for subsea control and monitoring
Analysis of both standard electro-hydraulic and all electric systems (electric actuated valves)Need for subsea sensors development to monitor oil in water content
• Challenge for maintenanceReplacement of modules Definition of reliability andintervention requirements(Capex vs. Opex)
26TUV/NEL Produced Water Club 23rd April 2010
Development is on- going for water treatment process meeting the followingrequirements for reinjection into the reservoir:
• 20 ppm of oil in water • 15 mg/l of solids in water
• Next steps:
Conclusion
2010 2011 2012 20142013 2015
First full scale installation
Define design cases, complete conceptual design
and cost estimates
High pressure testing and marinized design
Subsea pilot trial
We are at the beginning of this development to be done in cooperation with oil companies.
Operators are welcome to advise on design cases
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