0020 introduction to fpso design

11,141 views

Published on

Published in: Design

0020 introduction to fpso design

  1. 1. FPSO DESIGN- AN INTRODUCTION Kamal K. Ravi Engineering Projects& System Manager PTSC M&C
  2. 2. Introduction to Floating Production Systems Chapter 1
  3. 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. 4. Typical View of an FPSO
  5. 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. 6. FPS Application Chart
  7. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 17. External Turret Design
  18. 18. Spread Mooring
  19. 19. Buoy Yoke Mooring
  20. 20. Jacket Soft Yoke Mooring
  21. 21. Jacket Soft Yoke Mooring
  22. 22. Internal Turret Design (Tentech)
  23. 23. Detail of Internal Turret
  24. 24. Large Internal Turret
  25. 25. Disconnectable External Turret
  26. 26. Disconnectable Internal Turret
  27. 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. 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. 29. Tantawan Explorer Aft Accommodation
  30. 30. FPSO Firenze – Italy Aft Accommodation
  31. 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. 32. Accommodation – Forward FPSO Norne
  33. 33. Accommodation – Forward FPSO Asgard A
  34. 34. Number of FPSOs Built
  35. 35. Process Plant Layout • Layout based on -Safety -Operability • Most hazardous process areas -Furthest from accommodation (TSR) • Critical Level control -Close to midships
  36. 36. Distribution of FPSOs Worldwide (2008)
  37. 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. 38. FPSO Systems Chapter 2
  39. 39. FPSO Building Blocks • Main systems for FPSO are: - Hull type - Oil storage - Moorings - Fluid transfer - Topsides process plant - Offtake and export - Accommodation
  40. 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. 41. Tanker Conversion
  42. 42. Conversion Installing Topsides Modules
  43. 43. New Built Hull
  44. 44. Northern Endeavour New-Build
  45. 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. 46. The External Turret System
  47. 47. Simple External Turret
  48. 48. Large External Turret
  49. 49. Disconnectable External Turret
  50. 50. Internal Turret System
  51. 51. Internal Turret
  52. 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. 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. 54. Radial Swivel Joint
  55. 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. 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. 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. 58. Direct Ship to Ship Offtake
  59. 59. CALM Loading Buoy
  60. 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. 61. Cost Estimate Conceptual Design- Large FPSO
  62. 62. Turret and Mooring Systems Design Chapter 3
  63. 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. 64. Turret Overview
  65. 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. 66. Disconnectable External Turret
  67. 67. External Turret Permanent Mooring
  68. 68. External Turret – Permanent Moored
  69. 69. Internal Permanently Moored Turret
  70. 70. Internally Permanently Moored Turret
  71. 71. Maersk Curlew FPSO Turret - 1996
  72. 72. Maersk Curlew FPSO
  73. 73. FPSO Anasuria Turret Manifold Decks
  74. 74. Large Diameter Internal Turrets
  75. 75. Small Diameter Turrets
  76. 76. Internal (Submerged) Disconnect Turret
  77. 77. Submerged Turret
  78. 78. Spread Moorings
  79. 79. Bow Anchoring for Spread Mooring
  80. 80. Jacket or Tower Mooring
  81. 81. Tower Mooring
  82. 82. Ship’s Motion
  83. 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. 84. Mooring Chain Table
  85. 85. FPSO Mooring Spreads
  86. 86. Process Facilities Chapter 4
  87. 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. 88. Oil /Gas Separation • First stage HP separation • Second stage MP separation • Third stage LP separation • Electrostatic coalescing • Well test separation
  89. 89. Oil / Gas Separator with Wave Motion Internals
  90. 90. Overall Topsides Module Layout
  91. 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. 92. Water Injection • Seawater supply • Vacuum de-aeration • Chemical injection • Injection water delivery
  93. 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. 94. Utilities Integration Diagram
  95. 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. 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. 97. Alternative Technologies • Multi-phase flow metering • Subsea water separation • Subsea raw water injection • Multi-phase booster pumping • Subsea power distribution
  98. 98. An SBM Vessel
  99. 99. Power Generation Module
  100. 100. Utilities (CM+HM) Module
  101. 101. Water Injection Pumps
  102. 102. Water Injection Module
  103. 103. Chemical Injection & Water Injection
  104. 104. Oil / Gas Separation Module
  105. 105. Methanol Storage & Injection
  106. 106. Glycol Regeneration
  107. 107. Flare K.O Drums
  108. 108. End of a Hard Day’s Work
  109. 109. Mess Hall
  110. 110. Gourmet Kitchen
  111. 111. Her Own Power
  112. 112. Marine Systems Chapter 5
  113. 113. Marine Systems • Choice of Ship • Tank Arrangements • Loading/Offloading System • Cargo Pumps • Ballast System • Stops System • Inert Gas System • Vessel/Topsides Interface
  114. 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. 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. 116. FPSO Tank Arrangements
  117. 117. Cargo Offloading Systems • Floating Hose • Reeled Hose • CALM Buoy • Submerged Hose
  118. 118. Floating Hose Arrangement
  119. 119. FPSO Stern Offloading
  120. 120. Stern Offloading Hose Reel
  121. 121. Reeled Hose Arrangement
  122. 122. CALM Buoy
  123. 123. Submerged Hose System
  124. 124. Submerged Cargo Pumps
  125. 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. 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. 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

×