Floating Structure Review
Transcript of Floating Structure Review
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1November 2006
Review of Deepwater Floating Structuresand Dry Tree Semi
Developments
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2Deepwater Structures
Spar
Industry Accepted Because: Proven - Many years of
Operating history Functional - Used for a large
variety of functions, wet or dry tree
Scaleable Wide range of topsides payloads
Adaptable Applications worldwide
Tension Leg Platform (ETLP)
Semi-submersible (Semi)
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3Optimum Application Ranges
0
10,000
20,000
30,000
40,000
50,000
0 2,000 4,000 6,000 8,000 10,000Water Depth (ft)
F
a
c
i
l
i
t
y
P
a
y
l
o
a
d
(
s
t
)
SparsSemisTLP
Spar
SemiTLP
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4Deep Draft Semi Dry Tree Semi
DeepDraftDeepDraftTMTM SemiSemi
ESemi-II
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5TLP Design
Low heave and pitch natural periods (less than 4 seconds)
Minimum tether tensions
Minimum bending loads on TLP deck structure to reduce steel
Offset and set-down motions that can be tolerated by the riser system
Stability during installation and quayside HUC
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6Extended TLP (ETLP) Construction
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7ETLP Transit
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8Quayside Topsides Installation
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9Structural Weight Efficiency Ratio
Structural Weight Efficiency =
Total Topsides Payload
Total Hull Plus Deck Weight
Total Topsides Payload =
Weight of all deck equipment and facilities including quarters, drilling systems, etc. Also includes TTR loads, SCR loads and secondary deck steel. Topsides equipment or facilities carried in the hull, and hull ballast earmarked for future expansion are also included.
Total Hull Plus Deck Weight =
Structural steel weight of hull, hull marine systems, hull appurtenances and outfitting, and trim ballast. Also includes deck primary structural steel weight.
Structural Weight Efficiency =
Total Topsides Payload
Total Hull Plus Deck WeightStructural Weight
Efficiency =Total Topsides Payload
Total Hull Plus Deck Weight
Total Topsides Payload =
Weight of all deck equipment and facilities including quarters, drilling systems, etc. Also includes TTR loads, SCR loads and secondary deck steel. Topsides equipment or facilities carried in the hull, and hull ballast earmarked for future expansion are also included.
Total Hull Plus Deck Weight =
Structural steel weight of hull, hull marine systems, hull appurtenances and outfitting, and trim ballast. Also includes deck primary structural steel weight.
Total Topsides Payload =
Weight of all deck equipment and facilities including quarters, drilling systems, etc. Also includes TTR loads, SCR loads and secondary deck steel. Topsides equipment or facilities carried in the hull, and hull ballast earmarked for future expansion are also included.
Total Hull Plus Deck Weight =
Structural steel weight of hull, hull marine systems, hull appurtenances and outfitting, and trim ballast. Also includes deck primary structural steel weight.
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10
Efficiency Ratio Ranges for TLP Designs
Structural Weight
Efficiency
Structural Weight
Efficiency==
Total Topsides PyldTotal Topsides PyldTotal Hull + Deck WtTotal Hull + Deck Wt
Hull Form / LocationDesign Maturity
Ratio Range
TLPs in GoM As-Built 0.6 0.8
ETLPs in GoM As-Built 1.1 1.2
ETLPs in SE Asia Conceptual 1.4 1.5
ETLPs in W Africa As-Built 1.3 1.4
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11
Spar Design
High heave and pitch natural periods (greater than 25 seconds without risers)
Maximum offset of 7-9% water depth in damaged conditions
Maximum heel angle less than 10 in intact and damaged condition.
Wet tow draft shallow enough to offload hull if transport vessel is used
Structural strength for up-righting during installation.
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12
Spar Construction
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Spar Construction
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14
Spar Transportation
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Spar Installation
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Spar Topsides Installation
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Relative Deck Areas
Spar
Semisubmersible&
TLP
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18
Wellbay Layout - TTRs
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19
Riser Tensioner
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Design Basis Comparison of Hull Forms
GoM Environment 60 MBOPD & 200 MMCFD 20-person accommodation Work-over rig Hydro-pneumatic tensioners on TTRs
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Metocean Conditions for Comparison
100-Y ear H u rric an e C o n d itio n sW ATE R D E P TH (ft) 4 ,700
W AV E SS ig n if ican t W ave H e ig h t (f t) 40 .4P eak P e riod (sec) 14 .2M axim um W ave H e ig h t (ft) 70 .2
W IN D S - R eferen ced to 10m ab o ve M S L1 -H ou r S usta ined W ind S peed (ft/sec) 128
C U R R E N T S P E E D (ft/s )S urface 3 .6197 ft 3 .6328 ft 0 .65490 ft 0 .65656 ft 0 .65980 ft 0 .651640 ft 0 .65N ea r-B o ttom 0 .65
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Hull Forms and Dimensions
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Comparison of Weights and Payloads
0
5,000
10,000
15,000
20,000
25,000
Tops
ides
Lights
hip
Moori
ngs
SCR
TTRs
Balla
st
W
e
i
g
h
t
(
s
t
o
n
s
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ESEMISparETLP
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Tensioner Characteristics
Offset - Tension Curves
0
300
600
900
1200
1500
1800
2100
-16.0 -12.0 -8.0 -4.0 0.0 4.0 8.0 12.0 16.0
Stroke (ft)
T
e
n
s
i
o
n
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k
i
p
s
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TLP ESEMI Spar B-Can
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Well Patterns
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Surge Comparison
Surge RAO Comparison
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
0.0 3.0 6.0 9.0 12.0 15.0 18.0 21.0 24.0
Periods (sec)
S
u
r
g
e
R
A
O
(
f
t
/
f
t
)
ETLP ESEMI Spar
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Pitch Comparison
Pitch RAO Comparison
0.00
0.05
0.10
0.15
0.20
0.25
0.0 3.0 6.0 9.0 12.0 15.0 18.0 21.0 24.0
Periods (sec)
P
i
c
t
h
R
A
O
(
d
e
g
/
f
t
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ETLP ESEMI Spar
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Heave RAO Comparison
0.00
0.10
0.20
0.30
0.40
0.50
0.0 3.0 6.0 9.0 12.0 15.0 18.0 21.0 24.0
Periods (sec)
H
e
a
v
e
R
A
O
(
f
t
/
f
t
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ETLP ESEMI Spar
Heave Comparison
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Motion Response 100-Year Hurricane Intact Condition
0.00
4.00
8.00
12.00
16.00
20.00
Offset
(% de
pth)
Heave
Range
(ft)
Heel (
deg)
Yaw (de
g)
Deck
Acc. (ft
/sec2)
R
e
s
p
o
n
s
e
ESEMISparETLP
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Comparison of Range of Strokes
-18.00
-14.00
-10.00
-6.00
-2.00
2.00
6.00
10.00
14.00
max u
pstrok
e (ft)
max d
nstrok
e (ft)
max u
pstrok
e (ft)
max d
nstrok
e (ft)
max u
pstrok
e (ft)
max d
nstrok
e (ft)
R
e
s
p
o
n
s
e
ESEMISparETLP
100-Yr Intact
100-YrMooring Damage
100-Yr Hull Damage
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Range of Top Tension Factors (TTF)
0.00
0.50
1.00
1.50
2.00
2.50
3.00
max T
TF
min TT
F
max T
TF
min TT
F
max T
TF
min TT
F
R
e
s
p
o
n
s
e
ESEMISparETLP
100-Yr Intact
100-YrMooring Damage
100-YrHull Damage
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Selection Considerations for a Deepwater Floater
Spar ETLP Dry Tree Semi
Small in-place motions ; ; ;Large open deck areas : ; ;
Dockside HUC of topsides : ; ;Water depth insensitivity ; : ;
Minimum at-sea commissioning : : ;Redeployment ; : ;