1. FPSO DESIGN- AN INTRODUCTION
Kamal K. Ravi
Engineering Projects& System Manager
PTSC M&C

2. Introduction to Floating
Production Systems
Chapter 1

3. Floating Production Systems
• Classified as:
 Semi-submersible and tension leg platforms
- Little or no storage capacity
 Spars
- Limited storage capacities
 FPSO – primarily mono-hull vessel

4. Typical View of an FPSO

5. Water Depth and Sea States
• Water depths
 Shallow
-Less than 50m
 Moderate
-Down to 300m
 Deep
-Down to 1500m
 Ultra Deep
-Beyond 1500m
• Sea states
 Benign
-Hs 0 to 4.0m
 Medium
-Hs 4.0 to 9.0m
 Severe
-Hs 9.0 to 14.0m+
 Hs=significant wave
height

6. FPS Application Chart

7. History of the FPSO
• 1977 First FPSO-
Castellon Field
 Offshore Spain
 Mooring –SALM
 Water dept 117m
• During 1980s
 Moderate depths
 Benign waters
 Cost effective
solution
- For marginal fields
 Proven safety record

8. History of the FPSO
• During 1990s
- Deeper waters
- Rougher seas
- Black oil reservoirs
• Early 21st Century
-Ultra deep waters
-Large numbers of risers
-Very high throughputs
-Storage – VLCC Class
-Newly built vessels
-Handle gas liquids

9. The Pros and Cons
• Advantages
- Utilises existing ships
- Faster development
- Reduced upfront costs
- Early cash flow
- Re-usable
- Higher residual value
- Lower abandonment
costs
• Disadvantages
- No drilling
- Subsea wells only
- Rushed design can lead
to mistake
- Weather dependency
- Production
- Offtake

10. What is an FPSO?
• F = Floating – it looks like a ship – but is it?
• P = Production - Produces and processes a
reservoir fluid
• S = Storage – Vessel’s cargo tanks store
product crude
• O = offtake – Crude is offloaded to shuttle
tanker
• That is the Simple Look

11. Mooring the FPSO
• An FPSO is essentially a ship permanently moored on
the open ocean
• Stresses imposed on the hull need to be minimised
• Ship has to survive for life of project
• Weathervaning is a natural effect which minimises
stressess
• Allows ship to align itself with the wind, wave and
current
• Turret mooring allows weathervaning

12. Cargo Handling on FPSO
• An FPSO is a crude oil tanker
• Two issues are critically important
 Loading and offloading the cargo
- Creates stresses on hull- have to be minimised
-Achieved by load monitoring and ballast system
 Storing the product crude safely
- Cargo tank atmosphere potentially explosive
- Tanks must remain “inerted” at all times
- Achieved by use of inert gas system (IGS)

13. Production and Processing on FPSO
• Two issues important
 Sustaining and optimising reservoir productivity
- Sustaining reservoir pressure
- Optimising reservoir flow
- Assurance of flow from reservoir to processign centre
 Safe, efficient and effective processing
- Maximising liquids recovery
- Disposal of gas safety and economically
- Treatment and disposal of produced water
- Efficient use of chemicals to aid both production and
processing

14. FPSO Design Issues
• Main Technical Questions
 Selection of the mooring system
- Predominantly turret mooring, but spread mooring
and yoke mooring also used
 Location of the accommodation block
- Conventionally at aft end of ship
- New build vessels may have forward
accommodation
 Process plant layout, based on safety and operability

15. Turret Mooring System
• Mooring turret is unique FPSO feature
• Serves three purposes:
Anchors vessel at geo-stationary position
 Allows vessel to weathervane
 Provides conduit for fluid transfer
- Subsea reservoir infrastructure to
topside processing plant

16. Turret Designs
Turret designs based on location
- Either external to the hull of the vessel
- Or internally fitted inside the hull
Choice based on:
- Geographical location
* Sea states, strom systems, ice, etc
- Water depth
- Number of fluid transfer risers

17. External Turret Design

18. Spread Mooring

19. Buoy Yoke Mooring

20. Jacket Soft Yoke Mooring

21. Jacket Soft Yoke Mooring

22. Internal Turret Design (Tentech)

23. Detail of Internal Turret

24. Large Internal Turret

25. Disconnectable External Turret

26. Disconnectable Internal Turret

27. Location of Accommodation
• Largely influenced by position of turret
• Research shows that turret should be on
further aft than 19% of length of vessel
• Achieves optimal operational efficiency
- Maximises weathervaning
- Minimises “pitching” effect
• May exlude choice in placement of
accommodation

28. Accommodation in Aft Location
• Normal solution for ship conversions
• Allows for optimal positioning of turret
• Stern abandonment is safest option
• Crew downwind of fire / smoke / flame
 Additional engineering may be needed
- To protect “safe refuge’
- To allow for helicopter operations
- To minimise flare radiation effects

29. Tantawan Explorer Aft
Accommodation

30. FPSO Firenze – Italy Aft
Accommodation

31. Accommodation in in Forward
Location
• Most applicable for new build FPSOs
• Turret is aft of accommodation
• Crew upwind of fire / smoke / flame
• Forward abandonment may be difficult in
rough weather
• Motion effects may make living conditions
uncomfortable for crew

32. Accommodation – Forward FPSO
Norne

33. Accommodation – Forward FPSO
Asgard A

34. Number of FPSOs Built

35. Process Plant Layout
• Layout based on
-Safety
-Operability
• Most hazardous process areas
-Furthest from accommodation (TSR)
• Critical Level control
-Close to midships

36. Distribution of FPSOs Worldwide (2008)

37. Recent FPSO Developments (2000-2010)
• West Africa
- Serpentina, Mystras, Sanha, Kizomba,AKPO
- USAN
• Brazil
- Espadarte, Brasil
• Australasia
- Northern Endeavour, Venture 11
• South East Asia
- Su Tu Den
• Canada
- Terra Nova

38. FPSO Systems
Chapter 2

39. FPSO Building Blocks
• Main systems for FPSO are:
- Hull type
- Oil storage
- Moorings
- Fluid transfer
- Topsides process plant
- Offtake and export
- Accommodation

40. Hull Types
• Classic hull type for FPSO:
- Mono-hull, crude carrier classification
- Segregated ballast
- Mono-hull meaning single steel shell
- Double- hull not standard requirement
- Exceptions – GoM, NWS Australia
• Hull can be either:
- Existing carrier- suitable for conversion
- Newly built specifically for FPSO service

41. Tanker Conversion

42. Conversion Installing Topsides Modules

43. New Built Hull

44. Northern Endeavour New-Build

45. Moorings
• The moorings for an FPSO can be:
- Spread moorings
- Benign conditions
- Any water depth
- Jacket or tower moorings
- Moderate conditions
- Shallow waters
- Turret moorings
- Any conditions and water depth

46. The External Turret System

47. Simple External Turret

48. Large External Turret

49. Disconnectable External Turret

50. Internal Turret System

51. Internal Turret

52. Fluid Transfer System
• Function of system:
- To connect subsea risers to topsides process plant
• Fact
- Risers are stationary pipes
- Topsides plant is on weathervaning ship
• Problem
- How to connect the two
• Answer
- Fluid swivel

53. Fluid Swivels
• Predominant fluid transfer system is the fluid
swivel
• Commonly referred to as the radial swivel
joint
• The term toroidal swivel is used to describe
shape of fluid pathway

54. Radial Swivel Joint

55. Moorings and Fluid Transfer
• Fluid swivels only required for:
- Turret moorings
- Jacket moorings
• Spread moored FPSOs:
- Do not rotate around mooring point
- Do not require swivel joints

56. Topsides Process Plant
• Processing which occurs on an FPSO:
- Three phase separation of the well fluids
- Gas recompression
- Gas treatment
- Produced water treatment
- Injection water treatment
• Standard black oil processing
- Practiced worldwide

57. Offtake and Export
• Crude oil export from an FPSO
- Connection to a pipeline
- Direct ship transfer
- Using a surface hose either floating or
reeled
- Transfer through a loading buoy

58. Direct Ship to Ship Offtake

59. CALM Loading Buoy

60. Accommodation
• Two possible locations
- Bow or Stern
• Accommodation block contains temporary safe
refuge (TSR)
• Layout of topsides plant must be based on:
- Survivability of TSR
Greatest risks remote
Gas or smoke ingression via HVAC prevented
Fire and blast-proofing may need to be upgraded
- Unhindered personnel access to TSR from any point
on deck

61. Cost Estimate Conceptual Design- Large
FPSO

62. Turret and Mooring Systems Design
Chapter 3

63. Turret Mooring System
• Mooring turret is unique FPSO feature
• Serves three purposes:
- Anchors vessel at geo-stationary position
- Allows vessel to weathervane
- Provides conduit for fluid transfer
 Subsea reservoir infrastructure to topside
processing plant

64. Turret Overview

65. Turret Design
• Three types of turret mooring systems
- External
- Internal
- Submerged
• Each type can be sub-divided into:
- Disconnect type
- Permanent connect type

66. Disconnectable External Turret

67. External Turret Permanent Mooring

68. External Turret – Permanent Moored

69. Internal Permanently Moored Turret

70. Internally Permanently Moored Turret

71. Maersk Curlew FPSO Turret - 1996

72. Maersk Curlew FPSO

73. FPSO Anasuria Turret Manifold Decks

74. Large Diameter Internal Turrets

75. Small Diameter Turrets

76. Internal (Submerged) Disconnect
Turret

77. Submerged Turret

78. Spread Moorings

79. Bow Anchoring for Spread Mooring

80. Jacket or Tower Mooring

81. Tower Mooring

82. Ship’s Motion

83. Vessel Motion across the Sea Surface
• Based on the period
» Short period motion due to waves
– 6 to 20 second typically
» Longer period due to wind and waves
– Can be several minutes
– This is weathervaning
• Mooring forces increase with motion
» In other words in rougher the seas the greater are
the mooring forces
– More or stronger anchors

84. Mooring Chain Table

85. FPSO Mooring Spreads

86. Process Facilities
Chapter 4

87. Processing Facilities on a Typical FPSO
• Functional requirements
» Oil /gas separation
» Gas compression and treatment
» Produced water treatment and disposal
» Water injection
» Gas export / re-injection
» Support utilities
» Chemical injection and distribution

88. Oil /Gas Separation
• First stage HP separation
• Second stage MP separation
• Third stage LP separation
• Electrostatic coalescing
• Well test separation

89. Oil / Gas Separator with Wave Motion
Internals

90. Overall Topsides Module Layout

91. Gas Compression & Treatment
• The three compression stages and associated
compressors are:
» Flash gas compression K-201
» MP gas compression K-202
» HP gas compression K-203

92. Water Injection
• Seawater supply
• Vacuum de-aeration
• Chemical injection
• Injection water delivery

93. Support Utilities
• Fuel gas
• Flare & drainage
• Compressed air system
• Heating medium system
• Cooling medium system
• MP steam
• Seawater system
• Chemical injection
system
• Power generation

94. Utilities Integration Diagram

95. Chemical Injection System
• Consists of three sub-systems
» Topsides
– For oil / gas & injection water processing & protection
» Hydrate inhibition
– For production & gas processing
» Subsea
– For wellhead & flowline protection

96. Safety Assessment
• Need to consider
» Layout of equipment
» Consequences of fire / explosion
» Safety venting
» Design of the fire system
» Containment & drainage of process fluids

97. Alternative Technologies
• Multi-phase flow metering
• Subsea water separation
• Subsea raw water injection
• Multi-phase booster pumping
• Subsea power distribution

98. An SBM Vessel

99. Power Generation Module

100. Utilities (CM+HM) Module

101. Water Injection Pumps

102. Water Injection Module

103. Chemical Injection & Water Injection

104. Oil / Gas Separation Module

105. Methanol Storage & Injection

106. Glycol Regeneration

107. Flare K.O Drums

108. End of a Hard Day’s Work

109. Mess Hall

110. Gourmet Kitchen

111. Her Own Power

112. Marine Systems
Chapter 5

113. Marine Systems
• Choice of Ship
• Tank Arrangements
• Loading/Offloading
System
• Cargo Pumps
• Ballast System
• Stops System
• Inert Gas System
• Vessel/Topsides
Interface

114. Choice of Ship
• Factors affecting the
choice of ship are:
» Cost of conversion vs
new build
» Field life and
redeployment
» Need for additional
strengthening
» Cargo tank conditions
• Capacity of cargo
storage and offloading
• Condition of machinery
• Propulsion type
• Free area for topsides
plant

115. Vessel Sizes
• Tanker sizes used for FPSO conversion
» VLCC (very large crude carrier)
– 200,000 to 319,000 dwt
» Suezmax
• 120,000 to 200,000 dwt
» Aframax
• 75,000 to 120,000 dwt

116. FPSO Tank Arrangements

117. Cargo Offloading Systems
• Floating Hose
• Reeled Hose
• CALM Buoy
• Submerged Hose

118. Floating Hose Arrangement

119. FPSO Stern Offloading

120. Stern Offloading Hose Reel

121. Reeled Hose Arrangement

122. CALM Buoy

123. Submerged Hose System

124. Submerged Cargo Pumps

125. Tank Cleaning
• Crude Oil Washing – COW
» Removes wax and sediment build-up
» Carried out during offloading operations
» Uses warmed crude oil
» Following oil washing
– Water washing used prior to tank inspection
– Water washing can generate static charges
– Always done under inert gas blanket

126. Tank Vapour Recovery
• Today’s environment focus is on:
» Emissions!!
• Cargo tank operations – no exception
• Tank vapour recovery is modern trend
» Don’t vent tank vapour – re-use it!!
• Problem – its “inert” nature
• Answer – don’t use “inert” gas

127. Tank Blanketing
• Latest development is tank blanketing
» Use a gas that will:
– Exclude air, but be re-usable
» Hydrocarbon gas fills that need
• During loading tank gases
» Recovered for use as fuel
• During offloading separator gas
» Flows into tanks to exclude air