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 Application examples Summary

Application areas Upstream Midstream Downstream Safety Flow Process & Marine & Assurance & Subsurface Separation Offshore Subsea

Drivers for Expansion in Use of Simulation & CFD 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

Realism: Non-Newtonian Models Non-Newtonian fluids in STAR-CCM+ Time Independent Behavior Time Dependent Behavior (no-memory fluids, generalized (memory fluids) Newtonian modelling approach) Purely viscous Thixotropics Rheopectics Viscoelastics No Yield Stress Yield Stress Reversible • Linear Fluids Fluids • Cross • • • Non-linear Newtonian Bingham • Carreau-Yasuda • • Ostwald-De Herschel- Waele (Power Bulkley Law) • Carreau- Yasuda Key: • Cross Green = current capability in STAR-CCM+ Amber = current capability, application dependent Blue = under development generalized non-Newtonian models

Realism: Emulsion Modeling the pressure drop in pipes with a two phase Eulerian model (with no relative viscosity model) results in Crude oil A and seawater emulsion in horizontal a decrease in pressure drop with pipe of diameter 2.21 cm, velocity of 0.44 m/s 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. “ 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 Solu lution ion domain main for 3D RANSE SE comp mput utati ation on Solu lution ion domain main for 2D D Eule ler r comp mput utation ation t = -17.33 s t = 0 s t = 1.16 s

Flow induced vibration using STAR CCM+ Def.: U (x200); Field: VM stress cs #5 cs #4 cs #2

Thermal analysis example using STAR CCM+ CAD MODEL INSULATION EXPOSED STEEL Minimum fluid temperature Temperature Hydrate temperature Required Time cooldown time

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 100% WATER 100% GAS Contours of gas bubble concentration Contours of velocity magnitude and vectors

Erosion modelling example 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 - Geometry MAGNITUDE AND LOCATION OF EROSION AT REDUCER WILL BE HIGHLY INFLUENCED BY PROXIMITY OF BENDS UPSTREAM COMPUTATIONAL MODEL OF FLUID REGION

Erosion modelling example - Mesh 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 - Flow field solution CONVERGED FLOW FIELD ON SECTION PLANE

Erosion modelling example - Particle modelling 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 - Erosion models A variety of erosion correlations exist within STAR CCM+ – Ahlert model: – Haugen: – Nelson-Gilchrist: – Oka:

Erosion modelling example - Particle tracks Single solving step executed and trajectories of sand particles through carrier phase are calculated

Erosion modelling example - Erosion results Contours of erosion can then be plotted on wall surfaces

Erosion modelling example - Morphing 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 RATE OVER TIME

Erosion modelling example - Morphing MESH MORPHING OVER TIME

Erosion modelling example - Summary 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

Slug catcher with OLGA coupling (200 m) GAS OUTLETS ETS (24 km (24 km) (200 00 m) SLUG CATCHER ER TANKS KS 45 m x x 3 m m D DIAME METER TER INLET (24 4 km km) OIL OUTLETS TS

Pigging assessment 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 Abaqus determines the pig motion and deflections STAR-CCM+ Flow Solution using overset mesh for the moving pig

Summary 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