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