Impact of embedment on the thermal response of piliipelines. holbeach.pdf · Impact of embedment on...

Impact of embedment on the thermal response of i lipipelines.

Dr. James Holbeach, Staff ConsultantR i l M A t li MSi K

Experience that Delivers

Regional Manager, Australia, MSi KennyE: [email protected] W: +61 8 6314 2508 M: +61 417 553 757

Introduction: What?

• Precisely what you think!Burial / Embedment? What do we mean?

Precisely what you think!

Sea

Deeply BuriedS d / Deeply BuriedSand / mud

Unburied Partially Buried / Embedded

“Just” Buried

Experience that Delivers 1

Introduction: How?

• Three primary mechanismsThree primary mechanisms– Self Embedment– Metocean– Deliberate


Self Embedment: Sea floor


Self Embedment: Weight


Metocean: Spaghetti plot


Metocean: Cyclone/Hurricane/Typhoon/Big StormStorm


Metocean: Sediment


Metocean: currents


Deliberate: Pipelay


Deliberate: Trenching / Stability / Security


Outline

• ContextContext• Case Study• PhysicsPhysics• Theory• Formulas• Verification• New tool


Context:

• Mechanical issuesSo Why?

Mechanical issues• Stability Issues• Corrosion issues• What part do THERMAL issues play?


Context

• Corrosion modellingThermal

Corrosion modelling• Buckling• Pipeline walkingp g• Hydrate management• Blowdown / low temperatures

TEMPERATURE CONTOUR PLOT IN A TEMPERATURE CONTOUR PLOT IN A PIPE CROSS SECTION


Case Study

• Cooling section for corrosion: How long?Cooling section for corrosion: How long?

80 ºC 20 ºC80 ºC 20 ºC

Unins lated pipe

??m

Insulated pipeInsulated pipe Uninsulated pipe


The problem

What’s so difficult?


Physics: Partial Burial

• Unburied pipe U=20 W/m2KSurely you just

Unburied pipe U 20 W/m K• Just buried pipe U=10 W/m2K

• Half buried pipe U=15 W/m2K

• 25% buried pipe U=16.6 W/m2K


Physics: State of play

Burial Level Knowledge levelBurial Level Knowledge level

Unburied Well understood

Deeply buried Well understood

Partially Buried Not well understood

“Just” buried Not well understood


Physics: State of Play

• Old work– OLGA, Pipesim and Carslaw & Jaeger formulations approach the

unburied solution as burial depth -> 0m– Cant / should not use OLGA formulation for burial < ~1 Diameter.

A b i d t f tl i l t d ti– Assume buried component perfectly insulated - conservative

• “New” Work– Steady State- Morud et al (2007)– Steady State- Ovuworie (2010)

St d St t Z k i H lb h M (2012)– Steady State- Zakarain, Holbeach, Morgan (2012) – Steady State and Transient- MSi Kenny internal (2012+)


Formulas


Case study: What is important?

Tambient

• Overall heat transfer coefficient

q (heat flux)

Overall heat transfer coefficient– Three resistances– Straight forward calculation Tfl id

g– Often hin can be ignored

Tfluid

Inner film (hin) Pipe wall (kwall) External film (hex)


Verification: Colourful Figures and Diagrams (CFD)Diagrams (CFD)


STREAMLINES COLOURED BY VELOCITY MAGNITUDE [m/s] – CASE R2V09T065B050

Verification: Colourful Figures and Diagrams (CFD)Diagrams (CFD)


TEMPERATURE CONTOUR PLOTS [°C] – CASE R2V09T065B050

Cooling Section

Cooling Section Sizing?


Cooling Section

Cooling Section

Unburied Pipe 7 7kmUnburied Pipe = 7.7kmConservative = 13kmOptimised = 10.5 km

Saving: ~$20mil / line


Ramp-up

T=0 hr


Ramp-up

t=0.75 hr


Ramp-up

t=1.00 hr


Ramp-up

t=1.25 hr


Ramp-up

t=1.50 hr


Ramp-up

t=1.75 hr


Impacts

• Cooling Section length OptimisationTemperature profiles

Cooling Section length Optimisation• Difference in Buckling design• Hydrate management philosophiesy g p p• Temperature management for hydrate remediation• Wax management


Challenges

• No one formulation covers all casesModelling challenges

No one formulation covers all cases• Problems with incorporation in commercial software packages• No complete transient solutions ... Work in progressp p g• No clarity on external heat transfer coefficient (esp for natural convection)


Acknowledgements

• Erich Zakairain (Woodside / Schlumberger)Erich Zakairain (Woodside / Schlumberger)• Prabu Parthasarathy (MSIK – Regional Manager India)• Christian Chauvet (MSIK- Lead CFD)( )• Woodside (esp. Paul Millachip / Julie Morgan)


Impact of embedment on the thermal response of piliipelines. holbeach.pdf · Impact of embedment on...

Documents

Transcript of Impact of embedment on the thermal response of piliipelines. holbeach.pdf · Impact of embedment on...