Examples, Developments & Future Trends of Simulation in the Oil - - PowerPoint PPT Presentation
Examples, Developments & Future Trends of Simulation in the Oil & Gas Industry Alex Read & David Fielding March 17 th 2014 Overview Application Areas for CFD within O&G Drivers for increased use of CFD Technology improvements
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
– 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
Key: Green = current capability in STAR-CCM+ Amber = current capability, application dependent Blue = under development
No Yield Stress Fluids
Waele (Power Law)
Yasuda
generalized non-Newtonian models
Yield Stress Fluids
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 Solu lution ion domain main for 3D RANSE SE comp mput utati ation
Solu lution ion domain main for 2D D Eule ler r comp mput utation ation
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 Temperature
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
– 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
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
give 16800 tracks
– Two-way coupling between sand particles and carrier phase not required
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 ETS OIL OUTLETS TS SLUG CATCHER ER TANKS KS 45 m x x 3 m m D DIAME METER TER
(24 4 km km) (200 00 m)
(24 (24 km 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
STAR-CCM+ Flow Solution using
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