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Temperature calculations for covered pipelines

Jan Sagen, e-mail: jans@ife.no

Senior Research Scientist

Institute for Energy Technology, Kjeller 

http://www.ife.no

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Three major petroleum activities at IFE

Tracer technology Process and fluid flow

technology

Corrosion

technologyCharacteristics:

• Developed from competence built up in the nuclear field 25 years ago

•  Advanced experimental capabilities combined with theoretical

knowledge/ computation/simulation

• Close co-operation with the market. 40% funding from international

companies

• In international forefront within all three areas

Temperature calculations for covered pipelines

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Low pressure loop

Multiphase Flow

LaboratoriesWell Flow Loop

3-phase gammadensitometer 

Temperature calculations for covered pipelines

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Rockdumping

http://www.theartofdredging.com/rockdumping.htm

Temperature calculations for covered pipelines

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 Nordnes loading rock in a Norwegian quarry

http://www.theartofdredging.com/rockdumping.htm

Temperature calculations for covered pipelines

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Current status

• Offshore pipelines commonly trenched, covered with backfill

soils and/or gravel dump

• Soil/gravel layer affects the heat loss from the pipe• Temperature calculations are often critically important (hydrate,

wax, top of line corrosion)

• Heat transfer by convection (natural or forced) can be

significant.• Models are generally not available

Temperature calculations for covered pipelines

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Well and nearwell JIP IFE - SPT

O

LG

 A

ROCX

• IFE – SPT JIP with Statoil and Total

• OLGA - state-of-the-art multiphasesimulator 

• Rocx is 3-phase thermal near well

simulator coupled to OLGA

• OLGA-Rocx is an appropriate tool for

modelling flow dynamics in the near well

zone and in the well.

Temperature calculations for covered pipelines

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Modelling tool needed

• Will be designed for thermal calculations of covered pipelines

- Convective heat transfer in porous soil or gravel layers

• Stand-alone design tool or in combination with a pipeline simulator

• Needed for validation:

Realistic experimental data for flow and heat transfer in porous media

Temperature calculations for covered pipelines

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 ,K 

• Model will be based on existing thermal model for flow andtemperature in porous media

• Using porosity and permeability data

based on physical properties of the soil• Thermal convection will be modelled by solution of 

temperature and pressure equations

T P,

Permeability Porosity

Pressure Temperature

Boundary

conditions

Temperature calculations for covered pipelines

Future modelling tool

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Geometry example

• Grid follows the trench and pipe closely

• Exact calculation of grid properties

• Generalization to arbitrary geometries

Temperature calculations for covered pipelines

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Experimental data needed

• Realistic sea-bed configuration

• Measure permeability and porosity for cover material

• Measure detailed temperature profiles• Measure effective heat loss coefficients

Temperature calculations for covered pipelines

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IFE competence

• Thermal modelling has been a major activity at IFE for manyyears, some of the areas being:

• Thermal fluid model in OLGA including heat transfer throughthe pipe wall

• Thermo-mechanical models related to aluminium moulding

• Modelling of thermal convection in risers, shutdown scenarios

• Development of thermal near well simulator Rocx coupled toOlga

IFE posesses relevant laboratory experience and equipment forcarrying out thermal experiments

Temperature calculations for covered pipelines

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Innovation

• Tool for design & performance studies of covered pipes that

include convective heat transfer 

• Simple to use• Flexible configuration (GUI)

• Validated performance

• Realistic sea-bed set-up in the laboratory

Temperature calculations for covered pipelines

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Wide range of applications

• Design studies by comparison of heat transfer coefficients

• Evaluation of burying versus pipe-in-pipe technology

• Consequance of gravel being silted and soils being washed

Combined with pipeline simulator (e.g. OLGA):

• Study of worst case scenarios• Calculate steady state heat loss from pipeline

• Predict temperature behaviour during shut-down and start-up

• Flow assurance evaluation

• Improved top-of-line corrosion predictions

Temperature calculations for covered pipelines