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CFD Simulation in the Oil and Gas Industr y...................................................................................................................................................................................................................................

By : Engr. Mohd Nazir bin Ramli, Grad. IEM

A WORKING DEFINITION OFC O M P U TAT I O N A L F L U I DDYNAMICS (CFD)

CFD - a computational technologythat enables you to study the dynamicsof things that f low. Using CFD, you can build a computational model tha tre p resents a system or device that youwant to study. Then you apply the fluidflow physics and chemistry to thisvirtual prototype, and the software will

output a prediction of the fluiddynamics and related physicalphenomena. There f o re, CFD is asophisticated computationally-baseddesign and analysis technique.

CFD software gives you the powerto simulate flows of gases and liquids,heat and mass transfer, moving bodies,multiphase physics, chemical re a c t i o n ,fluid stru c t u re interaction andacoustics through computer modeling.

Using CFD software you can build a

virtual prototype of the system ordevice that you wish to analyse andthen apply real-world physics andchemistry to the model, and thes o f t w a re will provide you with imagesand data, which predict theperformance of that design.

THE BENEFITS OF CFDT h e re are three compelling re a s o n s

to use CF D software: insight, fore s i g h tand eff i c i e n c y.

I n s i g h tIf you have a device or systemdesign which is difficult top rototype or test throughexperimentation, CFD analysisenables you to virtually crawlinside your design and see howit performs. There are manyphenomena that you can witnesst h rough CFD, which wouldnt be vis ible through any othermeans. CFD gives you a deeperinsight into your designs.

F o r e s i g h tBecause CFD is a tool forp redicting what will happenunder a given set ofc i rcumstances, it can quicklyanswer many what if?questions. You provide a set of boundary conditions, and thes o f t w a re gives you outcomes. Ina short time you can predict howyour design will perform, and

test many variations until youarrive at an optimal result. All ofthis can be done before physicalp rototyping and testing.

E ff i c i e n c yThe foresight you gain fromCFD helps you to design betterand faster, save money, meete n v i ronmental regulations ande n s u re industry compliance.CFD analysis leads to shorter

design cycles and your productsget to market faster. In addition,equipment improvements are built and installed with minimaldowntime. CFD is a tool forc o m p ressing the design anddevelopment cycle allowing forrapid pro t o t y p i n g .

A P P L I C ATIONS IN OIL A N DGAS INDUSTRY

In oil and gas industry we can usethis powerful predictive tool in manyapplications ranging from drilling top roduction and processing such as toa n a l y s e ;

P re s s u re contours on stator androtor in a down-hole turbine.

Contours of volume fraction ofoil in a hydr o c y c l o n e .

Mud flow behavior for optimumcuttings removal in drill bitd e s i g n .

Contours of gas volume fractionin a gas-liquid separator.

Assessment of wind-drivenventilation through a platform.

Wind-induced surface pre s s u reson the platform.

For instance, in exploration-drill bi t, CFD analys is can pre dict thecoverage of lubricating mud over thecutting surfaces of a drill bit. Theresults will show a maldistribution of mud that causes uneven wear on the

drill bit, thus shortening its life.These predictions are borne out

by the actua l worn dr ill bi ts , whi chexhibit a very similar wear pattern.These results inform new designswhich can be tested with furtherCFD simulations before beingm a n u f a c t u re d .

CFD can also be applied to a host of p roblems such as:

Oil production in re s e r v o i r,including flow around

downhole injectors (i.e. CoiledTubing Fill Cleanout job). Drilling through complex fluids,

such as mud. Cavitation in rotating

equipment and pipe bends. Flows involving gas-solids,

liquid-solids or liquid-liquidm i x t u re s .

Gas dispersion in mud, in anda round plants or an off s h o replatform for safety analysis.

C O N C L U S I O NCFD helps in predicting the

performance of a particular design ando ffers suggestion to improve theexisting designs. A typical CFDsimulation might involve complexg e o m e t r y, which allows us to check thatthe model is a r e a s o n a b l ere p resentation of the engineer ingsituation and check for any errors thatmight have been introduced ingenerating the geometries.

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Oil, Gas and Mining Technical Division

The simulation results in data forthe velocitie s, pre s s u re, turbulence,t e m p e r a t u re and other data at each of the millions of points in the mesh.This data can be used to determineimportant engineering parameterssuch as drag coefficients, heat transferrate and maximum temperaturedepending on the purpose of thecalculations. The numerical analysisof the CFD results will tell us whatthe e ngineering parameters of intere s ta re, but it is the graphical illus trationof the results that explains why. It ist rue in CFD more than anywhere elsethat a single graphic can replace athousand word s .

The main benefit is that numericalexperiments can be performed to

illustrate the effects of design andre t rofit changes, without the need for acostly and time-consuming pro t o t y p ep r o g r a m .

R E F E R E N C E S

[ 1 ] Ramli, Mohd Nazir. ,Computational Simulation of Turbulence Convective HeatTransfer in MultipleRectangular Duct. Thesis,

UiTM, Shah Alam, Malaysia,May 2006

[ 2 ] Versteeg H.K. andMalalasekera W., A nI n t roduction toComputational FluidDynamics (The Fini te Vo l u m eMethod). Longman Scientificand Technical, UnitedKingdom, 1995.

[ 3 ] Bradshaw P., An Intro d u c t i o nto Turbulence and ItsM e a s u rement . Perg a m o n ,O x f o rd, 1971.

[ 4 ] Abbot M.R. and Basco D.R.,Computational FluidDynamics An Int ro d u c t i o nfor Engineers. Longman, 1989.

[ 5 ] Shaw C.T. , UsingComputational Fluid

Dynamics. Prentice Hall, UK,1 9 9 2 .

[ 6 ] Hinze J.O., Tu r b u l e n c e .McGraw-Hill, New Yo r k ,1 9 5 9 .

[ 7 ] Schlichting H., BoundaryLayer Theory. McGraw-Hill,New York, 1968.

[ 8 ] Launder B.E. and SpaldingD.B., Mathematical Models of Turbulence. Academic Pre s s ,

New York, USA, 1972.[ 9 ] FLUENT News, 2006