Multi-Fidelity Computational Flow Assurance: Linking SPT/Olga and STAR

Sreenadh Jonnavithula, Simon LoDewayne Anderson June 2009

OLGA-STAR coupled model - Objective

InletOutlet

Flow rates from OLGA to STAR

Pressure from STAR to OLGA

Flow rates from STAR to OLGA

Pressure from OLGA to STAR

To study 3D effects in in-line equipment: valve, junction, elbow, obstacle, jumper, separator, slug catcher, compressor, ...

CD-adapco – SPT partnership

• CD-adapco – SPT are partners in developing tools in Computational Flow Assurance. Both companies are fully committed from top management to technical engineers.

• Very close working relationship between engineers. • To develop the STAR-OLGA coupling:

– CD-adapco engineers from New York and London offices spent 3 days working with SPT experts in their Oslo head office.

– Lots of emails exchanges.– Lots of direct contacts between the two companies, in Houston and

Europe.• CD-adapco and SPT are partners in TMF and FACE research

consortia.

OLGA-STAR coupled model – example 1

InletOutlet

Flow rates from OLGA to STAR

Pressure from STAR to OLGA

OLGA-STAR coupled model – example 1

OLGA pipe:• 3 phase flow in pipe: gas, oil and water• Pipe diameter: 0.254 m• Pipe length is 1.5 km going up an incline of 15m• Fixed mass source at inlet

STAR pipe:• Same 3 phases• Same physical properties as OLGA• Same pipe diameter, 1 m long, small flow restrictions in flow

area (valve, fouling/hydrate deposit,...)

OLGA-STAR: 1-way and 2-way coupling

• One-way and Two-way coupling.

• One-way OLGA->STAR coupling:– OLGA sends outlet mass flow rates to STAR for inlet conditions.

• Two-way OLGA->STAR coupling:– OLGA sends outlet mass flow rates to STAR for inlet conditions.– STAR returns computed pressure at inlet to OLGA for outlet

pressure value.

OLGA-STAR coupling – example 1 results

• One-way OLGA-STAR coupling in first 100 s to initialise the system.

• Two-way coupling from 100 s.

• Change in mass flow is due to change in outlet pressure coming from STAR.

Two-way coupling

Note:Stratified flow at outlet of STAR pipe.

OLGA-STAR-OLGA coupled model - example 2

InletOutlet

Flow rates from OLGA to STAR

Pressure from STAR to OLGA

Flow rates from STAR to OLGA

Pressure from OLGA to STAR

Note:Annular flow at outlet of STAR pipe.

One OLGA session with two independent pipelines.

OLGA-STAR-OLGA coupled model - example 3

Inlet Outlet

Flow rates from OLGA to STAR

Pressure from STAR to OLGA

Flow rates from STAR to OLGA

Pressure from OLGA to STAR

Note:Annular flow at outlet of STAR pipe.

Water

Oil

OLGA-STAR-OLGA – mass flows in OLGA pipes

Upstream pipe

Downstream pipe –flows are getting through the STAR pipe into the downstream pipe

OLGA-STAR coupling – some details

• OLGA and STAR can run on any computer in the network. (Example: by accident we ran STAR in our Houston office and OLGA in our New York office).

• User specify which STAR boundary connect to which OLGA point.

• Density, dRho/dp, dRho/dt are interpolated from same OLGA data file to ensure consistency.

• Stratified flow is assumed at STAR inlet.

OLGA –Windows

STAR -Linux cluster

OLGA-STAR coupling – time step controls

Options:• Force OLGA and STAR to use same time step.

• Allow OLGA to take larger time steps. STAR to take smaller steps. STAR will interpolate OLGA results for intermediate steps. OLGA time step STAR time step

O1 S1S2S3

O2 S4S5S6

O3 S7

OLGA-STAR coupling – time step synchronization

• At start-up, STAR runs for 1 step to generate boundary values for OLGA.

• OLGA then runs for 2 steps dt apart (dt=STAR time step) to generate data at Time0 and Time1.

• OLGA is then allow to chose its own time step.• STAR will step from Time0 to Time1, interpolate OLGA results in

between.

OLGA-STAR coupled model - example 3

Inlet

Outlet

Flow rates from OLGA to STAR

Pressure from STAR to OLGA

OLGA-STAR coupling – CPU details

• STAR short pipe (examples 1 and 2) has 2000 cells• 1 processor• 1000 steps of 5e-4s to get 0.5s• CPU time is 854s (14 min)

• STAR wavy pipe (example 3) has 56,000 cells• 2 processors• 5000 steps of 5e-4s to get 2.5s• CPU time is 80727s (22.4 hrs)

Summary

• CD-adapco – SPT partnership and collaboration in development of Computation Flow Assurance tools.

• Close working relationship between the two companies.• Successful development of coupling between OLGA and STAR

for 1D analysis of long pipeline with detailed 3D CFD to study local effects.

• One-way and Two-way coupling between OLGA and STAR.• Successful demonstration of OLGA-STAR-OLGA two-point two-

way coupling.• Very interesting preliminary results obtained. Further test cases

and more detailed analyses will follow.