Upload
ngonhan
View
216
Download
2
Embed Size (px)
Citation preview
11/06/2015
1
Developing a more accurate description of soil-pipe interaction for the design of high temperature pipelinesDavid WhiteShell EMI Professor of Offshore Engineering
Fraser BransbySenior Principal Engineer, Fugro AG
SUT Evening Technical Meeting, Perth10 June 2015
Background references• White D.J., Westgate Z., Ballard J-C, de Brier C. & Bransby M.F. 2015. Best practice geotechnical
characterization and pipe-soil interaction analysis for HPHT flowline design. Proc. Offshore Technology Conference. Houston. OTC26026-MS
• Bransby, M.F., Borges Rodriguez, A., Zhou, H., Low, H.E. & White, D.J. 2014. Sediment mobility effects on seabed resistance for unburied pipelines. Proc. Offshore Technology Conference. Paper OTC25287
• Westgate Z.J. & White D.J. 2015. Quantifying spatial variability in pipeline embedment for subsea pipeline design. Proc. Int. Conf. Offshore Mech. and Arctic Engng. OMAE2015-42292
• White D.J., Leckie, S.H.F., Draper, S., Zakarian, E. 2015. Temporal changes in pipeline-seabed condition and their effect on operating behaviour. Proc. Int. Conf. Offshore Mech. and Arctic Engng. OMAE2015-42216
• Leckie, S., Draper, S., White, D.J., Cheng, L. & Fogliani N. 2015. Lifelong embedment and spanning of a pipeline on a mobile seabed. Coastal Engineering. 95:130-146.
• Hill A. & White D.J. 2015. Pipe-soil interaction: Recent and future improvements in practice. Proc. Int. Symp. on Frontiers in Offshore Geotechnics (ISFOG).
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Unravelling PSI design ranges
Pip
elin
e em
bedm
ent
Pip
e-so
il fri
ctio
n
Low estimate
High estimate
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Unravelling PSI design ranges• Consolidation hardening
Pip
elin
e em
bedm
ent
Pip
e-so
il fri
ctio
n
Low estimate
High estimate
Time
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
11/06/2015
2
Unravelling PSI design ranges• Consolidation hardening
• Self-burial
Pip
elin
e em
bedm
ent
Pip
e-so
il fri
ctio
nLow estimate
High estimate
Time
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Unravelling PSI design ranges• Consolidation hardening
• Self-burial
• Spatial variability
Pip
elin
e em
bedm
ent
Pip
e-so
il fri
ctio
n
Low estimate
High estimate
Space
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Unravelling PSI design ranges• Consolidation hardening
• Self-burial
• Spatial variability
Pip
elin
e em
bedm
ent
Pip
e-so
il fri
ctio
n
Low estimate
High estimate
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Unravelling PSI design ranges• Consolidation hardening
Pip
elin
e em
bedm
ent
Pip
e-so
il fri
ctio
n
Low estimate
High estimate
Time
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
11/06/2015
3
Axial PSI: General Model
Cycle number
Axi
al fr
ictio
n, F
A/W
(su-int/no)nc
tan res
Undrained
Drained
c/p
Effective stress, Vo
ids
ratio
, e Undrained
Dra
ined
From pipe weight
Consolidation Hardening
Cycle number, n
Mob
ilise
d st
reng
th
(su,1)
(su,n)
Effective stress,
Void
s ra
tio, e
ln R
sunsu1
R
(Partial) Consolidation Hardening
Cycle number, n
Mob
ilise
d st
reng
th
(su,1)
(su,n)
Effective stress,
Void
s ra
tio, e
Consolidation Hardening: ISB
-4-3-2-101234
-6 -4 -2 0 2 4 6
Shea
r stre
ss (k
Pa)
Horizontal displacement (mm)
Cycles 1-2 Cycles 5-6 Cycles 9-10
Boukpeti & White (2015)
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
11/06/2015
4
Consolidation Hardening: FEA
Yan et al (2014) David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Consolidation Hardening: Experiment
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 50 100 150
Axial fric
tion, F A/W
'
Axial displacement, x (mm)
12345678910111213
120 mm dia.1.4 m lengthSoft kaolin clayInitially 0.3D embedded
Smith & White 2014 David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Example: Downslope ‘Walking’
Typical ‘short’ flowlineon 3 seabed slope.SAGE-Profile 3D software.
Pipeline, Bathymetry and Operating Parameters ValuePipeline diameter (m) 0.3
Pipeline length (m) 4000Wall thickness (mm) 25
Submerged operating weight, W'op (kN/m) 1.5Seabed slope, (°) 3
Temperature range (startup to shutdown), T (°) 80
Soil and PSI Parameters Value
Undrained axial friction factor, FA/W'op = ud 0.4Drained axial friction factor, FA/W'op = d 0.8
Mobilization distance, xmob (mm) 10Volumetric stiffness ratio, / 0.1
Coefficient of consolidation, cv (m2/yr) 0.2White et al. (2015)
Limiting Axial Friction Cases
0
0.5
1
1.5
0 5 10 15 20 25
Acc
umul
ated
pip
elin
e w
alk
[m]
Cycles of startup or shutdown
No walking (FA/W = 0.8)
Solid line: analytical solution (Carr et al. 2006)Dotted line: analytical solution with elastic correction
Hollow dots: SAGE Profile FE simulations
White et al. (2015) David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
11/06/2015
5
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25
Axi
al E
quiv
alen
t Fri
ctio
n Fa
ctor
, A
Cycles of startup or shutdown
With Consolidation Hardening
Drained
(Initial) Undrained
White et al. (2015) David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
0
0.5
1
1.5
0 5 10 15 20 25
Acc
umul
ated
pip
elin
e w
alk
[m]
Cycles of startup or shutdown
With Consolidation Hardening
No walking
Solid line: analytical solution (Carr et al. 2006)Dotted line: analytical solution with elastic correction
Hollow dots: SAGE Profile FE simulations
Acceptable walking
White et al. (2015) David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25
Axi
al E
quiv
alen
t Fri
ctio
n Fa
ctor
, A
Cycles of startup or shutdown
Friction With Operational Effects
Drained
(Initial) Undrained
Partial consolidation cases
White et al. (2015) David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
0
0.5
1
1.5
0 5 10 15 20 25
Acc
umul
ated
pip
elin
e w
alk
[m]
Cycles of startup or shutdown
Range of Walking Responses
No walking
Acceptable walking
Acceptable walking?
Acceptable walking?
White et al. (2015) David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
11/06/2015
6
Consolidation Hardening: Field?
(m)
Hill & White (2015)David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Unravelling PSI design ranges• Consolidation hardening
• Self-burial
Pip
elin
e em
bedm
ent
Pip
e-so
il fri
ctio
n
Low estimate
High estimate
Time
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
As-laid condition
Leckie et al. (2015)David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Intermittent self-burial and spanning
Leckie et al. (2015)David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
11/06/2015
7
0.0002 m/s2
1 m/s after 5000 s. Impact on temperature profile
50°C
0.65DSimon Leckie, Erich ZakarianOMAE 2015-42216
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Unravelling PSI design ranges• Consolidation hardening
• Self-burial
• Spatial variability
Pip
elin
e em
bedm
ent
Pip
e-so
il fri
ctio
n
Low estimate
High estimate
Space
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
4500 4600 4700 4800 4900 5000Pi
pe e
mbe
dmen
t, w
/DKP (m)
Pipeline embedment variability
Westgate & White (2015) David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
11/06/2015
8
0
0.5
1
1.5
2
2.5
3
4500 4600 4700 4800 4900 5000
Lat
eral
bre
akou
t fri
ctio
n, H
brk/W
'
KP (m)
ActualP10P90
Breakout friction variability
Westgate & White (2015) David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
500
1000
1500
2000
2500
4500 4600 4700 4800 4900 5000
Hob
bs b
uckl
ing
forc
e, P
Hob
bs(k
N)
KP (m)
ActualP10P90
Buckle initiation force variability
Westgate & White (2015) David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
500
1000
1500
2000
2500
0 5000 10000 15000 20000
Hob
bs b
uckl
ing
forc
e, P
Hob
bs(k
N)
KP (m)
ActualP10P90
Buckle initiation force variability
Westgate & White (2015) David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Buckle initiation force variability
500
1000
1500
2000
2500
0 5000 10000 15000 20000H
obbs
buc
klin
g fo
rce,
PH
obbs
(kN
)KP (m)
ActualP10P90
Westgate & White (2015)
Envelope of possible buckle initiation force
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
11/06/2015
9
More tolerable design frictions
Roberts & Taavale (OTC 2014)See also: Gerginov et al. (OMAE 2014), Bruton & Carr (OPT 2015)
Less onerous UB friction
Full range
Conditional range
Bransby et al. (OTC2014)Breakout friction (initiation)
Res
idua
l fric
tion
(tole
rabi
lity)
Concluding comments
• Design pipe-soil friction ranges mask temporal and spatial effects
• Consolidation hardening – rise in axial friction• Potential reduction in pipeline walking
• Self-burial – increase in thermal insulation and stability• Potential improvement in corrosion and/or flow assurance• Potential reduction in (secondary) stabilisation measures
• Spatial variability• Less onerous buckling design via better PSI characterisation
David White (UWA), Fraser Bransby (FugroAG)SUT Evening Technical Meeting, 10 June 2015
Developing a more accurate description of soil-pipe interaction for the design of high temperature pipelinesDavid WhiteShell EMI Professor of Offshore Engineering
Fraser BransbySenior Principal Engineer, Fugro AG
SUT Evening Technical Meeting, Perth10 June 2015