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Transcript of Examples, Developments & Future Trends of Simulation … · Examples, Developments & Future Trends...
Examples, Developments & Future
Trends of Simulation in the Oil &
Gas Industry Alex Read & David Fielding
March 17th 2014
Application Areas for CFD within O&G
Drivers for increased use of CFD
Technology improvements
Application examples
Summary
Overview
Application areas
Upstream
Subsurface Flow
Assurance & Subsea
Process & Separation
Marine & Offshore
Midstream Downstream
Safety
Safety – Post-Macondo
New Frontiers – Deepwater, Unconventionals, HPHT, etc.
– Analysis Led Design
Technology – Software & Hardware – Applications Technically & Economically Viable
– Example: Virtual Wave Basin
– Realism: New Emulsion / Non-Newtonian models
– Efficiency: EOM
– Multi-physics/disciplinary/fidelity
Bottom Line: Partnership is Key
Drivers for Expansion in Use of Simulation & CFD
Non-Newtonian fluids in STAR-CCM+
Time Independent Behavior
(no-memory fluids, generalized
Newtonian modelling approach)
Time Dependent Behavior
(memory fluids)
Purely viscous Thixotropics Rheopectics Viscoelastics
Reversible
• Cross
• Carreau-Yasuda
• Linear
• Non-linear
Key:
Green = current capability in STAR-CCM+
Amber = current capability, application dependent
Blue = under development
No Yield Stress
Fluids
• Newtonian
• Ostwald-De
Waele (Power
Law)
• Carreau-
Yasuda
• Cross
generalized non-Newtonian models
Yield Stress
Fluids
• Bingham
• Herschel-
Bulkley
Realism: Non-Newtonian Models
Realism: Emulsion
Modeling the pressure drop in pipes
with a two phase Eulerian model (with
no relative viscosity model) results in
a decrease in pressure drop with
volume fraction, which is incorrect.
With the new relative viscosity models
we are able to predict increases in
pressure drop with increasing
dispersed phase volume fraction that
agree well with experiment.
Crude oil A and seawater emulsion in horizontal pipe of diameter 2.21 cm, velocity of 0.44 m/s
“Pipe flow of water-in-crude oil emulsions: Effective viscosity, inversion point and droplet size distribution” Jose Plasencia, Bjørnar Pettersen and Ole Jørgen Nydala, Journal of Petroleum Science and Engineering Volume 101, January 2013, Pages 35–43
Efficiency: Euler Overlay Method
t = -17.33 s
t = 0 s
t = 1.16 s
Solution domain
for 3D RANSE
computation Solution domain for 2D
Euler
computation
Flow induced vibration using STAR CCM+
cs #5 cs #4 cs #2
Def.: U (x200);
Field: VM stress
Thermal analysis example using STAR CCM+
Minimum fluid temperature
Hydrate temperature
Time Required cooldown time
Tem
pe
ratu
re
CAD MODEL
INSULATION
EXPOSED STEEL
Multiphase separation example
A range of multiphase models can be used to analyse
separation performance
VOF (volume of fluid) model can be used to analyse distribution
of phases and bulk fluid flow
– This can identify maldistribution into inlet devices and poor use of vessel
volume
Lagrangian droplet tracking can evaluate the transport of liquid
droplets in the gas space or gas bubbles within liquids
– Cut off sizes (smallest droplets being taken out of wrong outlets) can be
determined
Eulerian analysis can be used in certain cases e.g. gas induced
floatation separation vessels where high concentrations of gas
bubbles will exist
– Impact of gas bubble jet on flow in vessel can be accounted for
Multiphase separation example – VOF model
Multiphase flow entering inlet device and in vessel
Multiphase separation example – Lagrangian
model
Trajectories of 10 µm diameter oil droplets
Multiphase separation example – Lagrangian
model
Trajectories of 300 µm diameter oil droplets
Multiphase separation example – Eulerian model
Contours of gas bubble concentration
Contours of velocity magnitude and vectors
100% WATER 100% GAS
The following slides will provide an example of erosion analysis
using STAR CCM+
Upstream bends in this example will have significant influence
on the distribution of sand and therefore the erosion at critical
sections
CFD provides a method of assessing the erosion that will take
into account the sand distribution through the progression of
the pipework
For high erosion rates, as surfaces become eroded the
subsequent rate of erosion may change
– For example sharp edges may quickly become smoothed after which the
rate of erosion reduces
Mesh morphing techniques are used in this analysis to evaluate
the effects that the change in shape will have on the erosion
rate over time
Erosion modelling example
Erosion modelling example - Geometry
COMPUTATIONAL MODEL OF FLUID REGION
MAGNITUDE AND LOCATION OF EROSION
AT REDUCER WILL BE HIGHLY INFLUENCED
BY PROXIMITY OF BENDS UPSTREAM
Directed mesher is used to provide hexahedral mesh, largely
aligned with the flow direction with refinement at the walls
The carrier phase, hydrocarbon gas, is then solved
Erosion modelling example - Mesh
Erosion modelling example - Flow field solution
CONVERGED FLOW FIELD ON SECTION PLANE
The following models are used to analyse the sand phase
– Lagrangian multiphase – assumes sand concentrations <10% by volume
(sand on sand collisions are ignored)
– Drag force on particles – Schiller-Naumann (assumes spherical solid
particles), and virtual mass (effects of displacing carrier phase mass)
– Density of sand is specified for particle material
– Restitution coefficients (normal and tangential) specified for walls
– Haugen erosion model used (Ahlert, Nelson-Gilchrist and Oka also
available)
– Turbulent dispersion – accounting for turbulent fluctuations ‘randomising’
particle trajectories and producing greater number of trajectories to
sample from
• 10 parcel streams used per injection point (each cell face on model inlet) to
give 16800 tracks
– Two-way coupling between sand particles and carrier phase not required
• Volume loading of sand is too low to significantly influence carrier phase
Erosion modelling example - Particle modelling
A variety of erosion correlations exist within STAR CCM+
– Ahlert model:
– Haugen:
– Nelson-Gilchrist:
– Oka:
Erosion modelling example - Erosion models
Single solving step executed and trajectories of sand particles
through carrier phase are calculated
Erosion modelling example - Particle tracks
Contours of erosion can then be plotted on wall surfaces
Erosion modelling example - Erosion results
The mesh morphing tool within STAR CCM+ can be used to
modify the initial geometry based on the initial results
A vector field function is created: the erosion rate (in mm per
year) multiplied by face normal vector
Erosion modelling example - Morphing
Analysis changed to transient, required for morphing
Region > Motion specification set to Morphing
Fluid > Boundary > Wall set to Displacement
Morpher has the option of total or incremental
– Incremental option used to add displacement to existing displacement
each time
Mesh morphing is carried out by
– Morphing mesh based on erosion rate
– Re-evaluating flow field based on modified (morphed) geometry
– Re-evaluating particle tracks and erosion rate
– Repeating this process
Each cycle of this process represents the duration over which
the erosion is predicted
– e.g. mesh morphed according to displacement in mm per year means
each cycle represents one year
Erosion modelling example - Morphing
Erosion modelling example - Morphing
EROSION RATE OVER TIME
Erosion modelling example - Morphing
MESH MORPHING OVER TIME
Use of CFD to analyse erosion can identify where high spots of
erosion will occur
Influence of sand distribution can be accounted for
Morphing technique can be used to understand how erosion
rate will change (in magnitude and location) over time
Predictions of erosion magnitude are still difficult and
appropriate factors of safety for design should be used
according to models being applied
Erosion modelling example - Summary
Slug catcher with OLGA coupling
INLET
GAS OUTLETS
OIL OUTLETS
SLUG CATCHER TANKS
45 m x 3 m DIAMETER
(24 km)
(200 m)
(24 km)
(200 m)
Is the combination of gas flow rate and pig geometry correct to
move pig through pipe-line and up an incline?
Will be pig deform as it travels round the pipe bend?
What stresses will be caused in the pig?
Overset mesh technique used to capture motion of pig
Fluid analysis in STAR CCM+ coupled to structural analysis using
Abaqus
Two way coupling used in a transient simulation
Pigging assessment
Pigging assessment S
TA
R-C
CM
+ F
low
So
lutio
n u
sin
g
ove
rse
t m
esh
fo
r th
e m
ovin
g p
ig
Abaqus determines the pig motion and deflections
CFD increasingly standard part of O&G engineering processes
Drivers
– Safety
– New Frontiers
– Technology – Software & Hardware
CD-adapco working closely with Industry Partners
Application examples
Summary