The Low Motion FPSO (LM-FPSO)7a55cadfc823f7512d24-d084a9f35e8709e3877657621c88363c.r68.cf3.r… ·...

The Low Motion FPSO

(LM-FPSO)

The SCR and TTR Friendly Floater in Harsh

Environment

Alaa Mansour, Ph.D Marine Engineering Manager

Outlines

Field Development Challenges

The Low Motion FPSO (LM-FPSO)

• The Design

• The Constructability

• The Install-ability

• The Performance

• The Economics

Case Study: Dry Tree LM-FPSO in South China Sea

The Semisubmersible Version - TLS

The Business Case

Scope and Required Funding

Concluding Remarks

Slide 2

Outlines



• The Design



• The Performance

• The Economics



The Business Case


Concluding Remarks

Slide 3


Lack of Infrastructures/Remoteness

Requirement for DVA to wells

Water depth

Persistent swells

Harsh environment

Large number/diameter risers

Inherently high dynamic floater

0

0.2

0.4

0.6

0.8

1

1.2

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5 15 25 35

Hea

ve (

m/m

)

Period (s)

0 22.545 67.590 112.5135 157.5180

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5 15 25 35

Ro

ll (d

eg/m

)

Period (s)

0 22.5

45 67.5

90 112.5

135 157.5

180

Slide 4

Riser feasibility

FPSO or FPU+FSO/FPSO

TTR feasibility or Separate DTU

FPSO Heave FPSO

Roll


Question?….

Can we develop FPSO that offers:

High oil storage capacity and deck payloads

Superior motion response - TTR/SCR/mooring friendly

No turret or swivel

Large number/ large diameter risers

Fast deployment & decommissioning

Quayside integration

Simple and efficient hull form

Maintain simple topside layout

Commercially attractive (CAPEX & OPEX)

Low risk and minimum or no schedule impact

Slide 5

Outlines



• The Design



• The Performance

• The Economics



The Business Case


Concluding Remarks

Slide 6

The LM-FPSO Design

Slide 7

Conventional hull construction

Conventional Topside

Conventional Mooring System

Short Tendon Pipe No couplings

Solid Ballast tank (SBT)

Tendon Bottom receptacle

Tendon Top Connector

SCRs / Umbilicals

The LM-FPSO Constructability

► Simple hull form

► Stiffened plate structure

► Simple fabrication

► SBT fabricated independently

► Solid ballast is added in SBT

► Hull modules are integrated above SBT

► Topside integrated

► Mooring chains are used to connect SBT to hull

► Dry dock is flooded

Slide 8

The LM-FPSO Install-ability

Slide 9

Wet-tow


Slide 10

Positioning and Ballasting


Slide 11

Tendon Installation

The LM-FPSO Performance

Slide 12

The mass of the SBT:

Maintains positive tendon tension in all design conditions

Ensures full coupling in heave, roll and pitch

Ensures full coupling in the slow motion surge/sway & yaw

Provides high stability (high GM) – less compartments

SBT mass and added mass

Long heave, roll and pitch natural periods

Significantly low heave roll/pitch motions

The relative motion in surge, sway and yaw

Limited to first order

Much less than TLP hull-to-foundation relative motions

► Very long Heave Natural period

► Significantly reduced heave response in WF

► Very long Roll Natural period

► Significantly reduced Roll response in WF & LF

Slide 13

Typical Heave Response Typical Roll Response


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RY

[deg

]

Time [s]

DM-FPSO Hull vs. SBT, Pitch Motion

FPSO RY SBT RY


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Z [m

]

Time [s]

DM-FPSO Hull vs. SBT, Heave Motion

FPSO Z w/o Mean

SBT Z w/o MeanTypical Heave

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6000 6050 6100 6150 6200 6250 6300 6350 6400 6450 6500

RX

[d

eg]

Time [s]

DM-FPSO Hull vs. SBT, Roll Motion

FPSO RX SBT RXTypical Roll

Typical Pitch • Full coupling in heave, roll and pitch modes

• Very low heave roll/pitch motions, less than a third that of Spar, almost TLP like

Slide 14

0

5

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15

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X [

m]

Time [s]

DM-FPSO Hull vs. SBT, Surge Motion

FPSO X SBT X

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5

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Y [m

]

Time [s]

DM-FPSO Hull vs. SBT, Sway Motion

FPSO Y SBT Y


Slide 15

Typical Surge Typical Sway

-1.00

-0.80

-0.60

-0.40

-0.20

0.00

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0.40

0.60

0.80

1.00

6000 6050 6100 6150 6200 6250 6300 6350 6400 6450 6500

RZ

[deg

]

Time [s]

DM-FPSO Hull vs. SBT, Yaw Motion

FPSO RZ SBT RZ

Typical Yaw

• Full coupling in Surge, Sway and

yaw modes • Relative motion is quite small

0

5000

10000

15000

20000

25000

30000

200 2200 4200 6200 8200 10200

Bo

tto

m T

ensi

on

[kN

]

Time [s]

Critical Tendon Bottom Tension

Critical Tendon Bottom Tension


Slide 16

• Tendon tension is positive even in survival conditions

• LM-FPSO to SBT Relative motion is less than that of TLP-to-Foundation.

Tendon Tension

TLP vs LM-FPSO Dry Tree & Harsh Environment

1000 yr condition


Slide 17

VIM Response

Current speed = 1.1 m/sec Vr = 3.7 A/D = 0.07


Slide 18

SBT Structural Analysis


Slide 19

SBT Structural Analysis

The LM-FPSO Economics

Compared to the corresponding conventional FPSO:

Slide 20

Dry Tree – Harsh Environment

Wet-Tree Persistent Swell

Hull Steel 10-15% Increase -

SBT Steel (% of hull steel) 14% 5%

Solid Ballast (% of Displacement) 25% 15%

Tendon system TIC/tendon $4.1MM $4.1MM

Offloading Buoy cost $100MM Increase

Mooring system $15MM Increase $25MM Reduction

SLWR to SCR (per riser) $15MM Reduction $15MM Reduction

Turret $250MM Reduction -

Eliminate DTU (CAPEX) - Each $500MM Reduction -

Topside cost $50MM Reduction -

OPEX $100MM Reduction? -

Decommissioning $100MM Reduction -

Outlines



• The Design



• The Performance

• The Economics



The Business Case


Concluding Remarks

Slide 21

Dry Tree LM-FPSO in South China Sea

Water depth = 500 m

Topside payload = 25,000 MT

1.0 MMBBL Storage

15 TTRs

1 Multiphase production SCR

Environment: .

Slide 22

1,000 Yr 100 yr

Hs (m) 15.8 13.5

Tp (sec) 16.5 15.2

Ws (m/s) 51.6 49.8

Cs @ surface (m/sec) 3.9 2.4


Slide 23

L x w x H (m) 105.0 x 105.0 x 51.5

Corner radius (m) 10.5

Draft / Freeboard (m) 33.5 x 22.0

Center Well (L x W) (m) 60.7 x 60.7

Hull Lightship Wt (Mt) 44,330

Displacement (Mt) 227,768

L x W x H (m) 142.5 x 105.0 x 3.7

Center Opening L x W (m) 24.4 x 14.6

SBT steel Weight (Mt) 6,076

Solid ballast weight (Mt) 49,556

Mooring (-) 16 Chain-PE-Chain

Platform Chain Dia x L (mm x m) 162 mm R4S x 100 m

Polyester Dia x L (mm x m) 305 mm x 750 m

Platform Chain Dia x L (mm x m) 162 mm R4S x 150 m

Tendons (-) 16 @ 44"OD x 1.7"

Length (m) 88.0

Wt weight (Mt) 12.0

Heave Np (sec) 25.0

Roll/Pitch Np (sec) 46.0

GM (m) 31.9

Integrated Platform Lightship weight (Mt) 71,134

Hull+SBT Draft (inc. SB) (m) 12.3

Solid ballast is added in dry dock (-) YES

Lightship Draft (no solid ballast) (m) 4.9

The Hull

The SBT

The Mooring System

System Natural periods

Pre-service Key Figures


Slide 24

Heave RAO Roll Response


Slide 25

Variable Unit 1,000-yr 100-yr

Max offset % 11.7% 8.7%

Max SCR Porch Velocity (m/s) 1.7 0.9

Max heave (SA) (m) 4.0 3.1

Max combined Roll/pitch (SA) (deg) 3.9 3.4

Max Yaw (deg) 1.8 1.8

Max Hull-SBT rel. horizontal motion (m) 18.8 13.5

Minimum tendon tension (Mt) -170 599

Max Tendon Tension (Mt) 6,411 5,178

TTR dynamic Stroke (m) 7.2 4.6

Max Keel Joint Reaction (Mt) 108 59

Max Von Mises Stresses (MPa) 551 358


Slide 26

The System Performance

1,000-yr Critical Event 100-yr Critical Event

LM-FPSO + ONE TLP Cost Delta

Fabrication cost delta (Hull + SBT) $50MM

Transportation & Installation $10MM

Solid Ballast TIC (at quayside) $5MM

Mooring system delta $15MM

Tendon cost including Installation (TIC) $65MM

Offloading buoy TIC $100MM

Additional Tensioner costs $24MM

Eliminate one TLP (Hull& Mooring T&I) -$500MM

Topside saving -$50MM

No turret -$250MM

No FTL from One TLPs -$30MM

Decommissioning saving of 1 TLPs -$100MM

OPEX delta -$100MM??

Total Delta -$761 MM


Compared to a Turret-Moored FPSO + TLP in SCS

Slide 27

Outlines



• The Design



• The Performance

• The Economics



The Business Case


Concluding Remarks

Slide 28


Similar technology is applicable to conventional semisubmersibles designs to significantly improve their motions – Tension Leg Semisubmersible (TLS)

Slide 29

The TLS Semi – In-place

Tendon Porch

Tendon bottom receptacle


Slide 30

The TLS Semi – Pre-service


Slide 31

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Period (sec)

Heave R

AO

(ft

/ft)

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Wave E

nerg

y S

pectr

um

(ft

^2-s

ec/r

ad

)FHS SemiConventional

SemiSpar

Wave

Energy

H1000

Outlines



• The Design



• The Performance

• The Economics



The Business Case


Concluding Remarks

Slide 32

The Business Case

FPSO market share is greater than the combined FPU market

Potentially replace the common development scheme in west Africa (TLP+FPSO) … big market share (Example Maersek Chissonga, Hess Ghana)

Attractive solution for Liuhua development in SCS

Attractive solution for Talisman development in Vietnam

No feasible riser solution on FPSO for ultra-deepwater (Example Petrobras Pre-salt)

Industry is developing FPSO with SCRs for the GoM

Enable dry tree Semi with potential application (Mad Dog 2, Shenandoah, ..etc)

Improved semisubmersible response in wet tree application (CVX Jansz Io, Equus,…etc)

Slide 33

Outlines



• The Design



• The Performance

• The Economics



The Business Case


Concluding Remarks

Slide 34


Develop a basis of design

Develop a LM-FPSO design that meets the BOD.

Perform compartmentations and stability analysis

Perform hydrodynamic and mooring analysis

Perform TTR analysis

Prepare model test specs (wind tunnel test, wave basin test, and towing tank test)

Perform Tendon top and bottom connector fatigue (ongoing)

Perform structural analysis (ongoing)

Perform model tests

Perform model test calibration

Verify the design based on model test to ensure it still meets the BOD

3D rendering

Presentation and marketing material

Slide 35


RDC contribution of $178K (55%) with WP/INTECSEA covering:

* $55,000 USD in cash

* $55,000 USD in-kind

Potentially RDC can contribute $200K (62%) with WP/INTECSEA covering the $121,810 (38%):

* $33,000 USD in cash

* $55,000 USD in-kind

Slide 36

Outlines



• The Design



• The Performance

• The Economics



The Business Case


Concluding Remarks

Slide 37

Concluding Remarks

The LM-FPSO is an enabling solution for TTR and SCR on FPSOs in harsh environment

It avoids the need for a separate DTUs. Compared to FPSO+TLP a $760 MM saving is estimated

The LM-FPSO offers

• High oil storage capacity and deck payloads

• Superior motion response - TTR/SCR/mooring friendly

• No turret or swivel

• Large number/ large diameter SCRs

• Fast deployment & decommissioning

• Quayside integration

• Simple and efficient hull form

Slide 38

Concluding Remarks

The LM-FPSO offers (cont.)

• Maintain simple topside layout

• Low risk and minimum or no schedule Impact

• Flexible ballast compensation capacity

The LM-FPSO & TLP when project ready will be a game changer to the industry

Required funding is about $55K USD in Cash and $55K USD in-kind contribution based on funding of $178K USD from RDC

Slide 39

INTECSEA Floating Systems

Alaa M. Mansour, Ph.D.

Marine Engineering Manager

575 North Dairy Ashford Rd.

Houston, TX77079

USA

1 281-206-8455 (O)

[email protected]

Contact Information

mailto:[email protected]

The Low Motion FPSO (LM-FPSO)7a55cadfc823f7512d24-d084a9f35e8709e3877657621c88363c.r68.cf3.r… ·...

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