24/2/2015 General Knowledge on oil and gas http://www.p3planningengineer.com/oil_N_gas/general.htm 1/7 General Petroleum industry is a main energy industry. It has a huge chain of value from upstream to the downstream industries, such as oil exploration, oil extraction from wellhead, storage, measurement, transportation, refinery, petrochemical and chemicals. Since the industry is all about dealing with various hydrocarbon products, “hydrocarbon industry” is another name for the industry. Crude oil from the field reservoir usually has gas, water, and sediment in it. They are highly variable, with no two exactly alike. One crude may be bright green in colour, sweet smelling and as fluid as water. Another may be jet black and have an unpleasant sulfurous smell. Yet another may be pink and stack up in a pile when poured on the ground on a hot day. At the other extreme, gas condensate is colourless and will completely evaporate if left uncontained. The specific characteristics of each crude reflects its unique blend of sizes and types of hydrocarbon molecules, with thousands of different compounds in the mixture. This extreme varability is why the material was named “crude”. It is indeed a crude material, being messy, unstable and dangerous to handle. Essentially unstable in its initial form, crude must be refined – broken down – into products with the specific characteristics to handle certain jobs well, e. g., gasoline and diesel to power engines, fuel oil to heat homes, etc. This is the role of refineries. Very little of the crude is produced by refiner own company. Instead, it is generally purchased on the open market. The industry has a very efficient market operating between production and refining. Producers can count on getting a good price for their crude anywhere in the world and refiners can count on being able to purchase feedstock at a good price. Crude is traded freely, often changing hands several times as it takes the most efficient route between the producing fields and the refinery. Crude oil can be transported from the producing field to the refinery in a variety of conveyances. For onshore production, tank trucks, railroad tank cars, and barges on inland waterways are used to some extent, but pipelines are the dominant mode of transportation. Pipelines are also used to bring production ashore from offshore fields located reasonably near to land. For most export operations around the world, marine tankers are the only choice available. The bulk of the enormous Middle East production, for example, is shipped to all parts of the world in tankers. Most of the water and sediment have to be removed before the crude can be sold to a shipper. Also, gas and oil must be separated from each other. Therefore, surface processing facilities with separation, measurement and storage are built close to the oil field. Also, there are special vessels called separators and treaters being employed to separate fluids and to remove emulsified water from oil.
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General
Petroleumindustryisamainenergyindustry.Ithasahugechainofvaluefromupstreamtothedownstreamindustries,suchasoilexploration,oilextractionfromwellhead,storage,measurement,transportation,refinery,petrochemicalandchemicals.Sincetheindustryisallaboutdealingwithvarioushydrocarbonproducts,hydrocarbonindustryisanothernamefortheindustry.
Crudeoilfromthefieldreservoirusuallyhasgas,water,andsedimentinit.Theyarehighlyvariable,withnotwoexactlyalike.Onecrudemaybebrightgreenincolour,sweetsmellingandasfluidaswater.Anothermaybejetblackandhaveanunpleasantsulfuroussmell.Yetanothermaybepinkandstackupinapilewhenpouredonthegroundonahotday.Attheotherextreme,gascondensateiscolourlessandwillcompletelyevaporateifleftuncontained.Thespecificcharacteristicsofeachcrudereflectsitsuniqueblendofsizesandtypesofhydrocarbonmolecules,withthousandsofdifferentcompoundsinthemixture.
Thisextremevarabilityiswhythematerialwasnamedcrude.Itisindeedacrudematerial,beingmessy,unstableanddangeroustohandle.Essentiallyunstableinitsinitialform,crudemustberefinedbrokendownintoproductswiththespecificcharacteristicstohandlecertainjobswell,e.g.,gasolineanddieseltopowerengines,fueloiltoheathomes,etc.Thisistheroleofrefineries.
Verylittleofthecrudeisproducedbyrefinerowncompany.Instead,itisgenerallypurchasedontheopenmarket.Theindustryhasaveryefficientmarketoperatingbetweenproductionandrefining.Producerscancountongettingagoodpricefortheircrudeanywhereintheworldandrefinerscancountonbeingabletopurchasefeedstockatagoodprice.Crudeistradedfreely,oftenchanginghandsseveraltimesasittakesthemostefficientroutebetweentheproducingfieldsandtherefinery.
Crudeoilcanbetransportedfromtheproducingfieldtotherefineryinavarietyofconveyances.Foronshoreproduction,tanktrucks,railroadtankcars,andbargesoninlandwaterwaysareusedtosomeextent,butpipelinesarethedominantmodeoftransportation.Pipelinesarealsousedtobringproductionashorefromoffshorefieldslocatedreasonablyneartoland.
Formostexportoperationsaroundtheworld,marinetankersaretheonlychoiceavailable.ThebulkoftheenormousMiddleEastproduction,forexample,isshippedtoallpartsoftheworldintankers.
Mostofthewaterandsedimenthavetoberemovedbeforethecrudecanbesoldtoashipper.Also,gasandoilmustbeseparatedfromeachother.Therefore,surfaceprocessingfacilitieswithseparation,measurementandstoragearebuiltclosetotheoilfield.Also,therearespecialvesselscalledseparatorsandtreatersbeingemployedtoseparatefluidsandtoremoveemulsifiedwaterfromoil.
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Separatetheproducedfluidsintostremasofoil,gasandwaterforsaleanddisposal
Removefreewaterfromthewellbyknockouts
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Emulsion,amixtureofwaterandoil,tobeseparatedbywashtankwithflume
Refineries
Crudeoilcannotbeusedasafuelitself,becauseitcontainssuchabroadspectrumofmolecularsize.Tobepracticalasafuel,amaterialmusthaveknownburningcharacteristicssothatitcanbematchedwithanappropriateburnersystem(engine,boiler,etc.).
Thefirststepinarefineryistosplitcrudeintoseveralfractionsor"cuts"tocutthelargemoleculesofthecrudeintosmallervarioushydrocarbonproducts.Eachcutisconcentratingaparticularrangeofmolecularsizes.Forexample,oneofthecutsmightbelightgasesdescribedas"butanesandlighter"aheaviercutmightbekerosene.Thecutsaremadewithadistillationprocessthatemploysselectivevaporizationandrecondensation.
Thehighestvaluedpetroleumproductsarethe"whiteproducts",whichincludegasoline,diesel,jetfuel,andheatingoil.Productionofthese"middleofthebarrel"products,particularlygasoline,ismaximizedbyconvertingasmuchaspossibleofthelesservaluedgasesandtheheavier"bottomofthebarrel"materialstowhiteproducts.Thisisdonebyalteringthemoleculesasfollows:
Polymerizationisusedtocombinethesmallgasmoleculesintolarger,middleofthebarrel,moleculesCrackingisusedtobreakupthelarge,bottomofthebarrel,moleculesintosmalleronesIsomerizationaltersthearrangementofatomsinamoleculewithoutaddingorremovinganytheatoms
Theprocessesemployedtocutorrefinethecrudeincludeatmosphericdistillation,vacuumflashing,thermalcracking,catcracking,hydrocracking,gasplant,alkylation,catalyticreformingandblending.Roughly,thesearechainofprocess,meaningtheyieldofthepreviousprocessbecomesthefeedstockofthenextprocess,withdistillationbeingtheinitialprocessandblendingthefinalone.
DistillationTounderstandhowtheatmosphericdistillationtowerworks,letsusetapwaterbeingboiled(vaporized),thencooledsothatitrecondenses.Thisprocesscreatesdistilledwater,whichispurerthantheoriginalwaterbecauseonlytheH20moleculesvaporizedandleftthevessel.Thevariousnonvolatileimpuritiesinthetapwaterremainbehind,buildingupinconcentration,andeventuallyprecipitatingoutasasolidresiduewhenthevesselboilsdry.Thisprocessfunctionsthentoseparatethewaterfromtheimpurities.
Intheaboveexample,waterisboiledat100C(atsealevel).The100Ciscalledwater'sboilingpointandisspecifictothewatermolecule.Eachofthehydrocarbonmoleculeshasitsspecificboilingpoint,withthesmallerthemolecule,theloweritsboilingpoint.Thisisthekeytocuttingcrudeinadistillationtower.
Atmosphericdistillationistheinitialprocessinarefinery.Itsfractionatingtoweralargediameterverticalvesselwithmultipleinternalcontactortraysisthelargestintherefinery.Thecrudeisheated,vaporizingmostofit,then
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injectedintothebaseofthetower.Vaporsrisingthroughportsinthetrayscomeintocontactwithcondensedliquidsworkingdownwardthroughthecolumn.Thisinterchangecontinuallyvaporizessomeliquidandcondensessomegas,establishinganequilibriumthroughoutthecolumnwithheaviermaterialtowardthebaseandlightermaterialtowardthetop.Productcutsarecontinuouslyremovedfromthetowerthroughsidedrawsspacedalongitsverticallength.Thelocationofeachsidedrawisdesignedtotapaspecificboilingpointrangeofmaterial.
Mechanismofdistillingwater
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Distillationtower
Twotowersunderconstruction
BlendingBlendingoperationsarethefinalstep,combiningthevariousoutputsofalltheprocessesintothefinalproductsthataresold.Theblendingoperationhasamajorimpactonmanagingtherefinery.Itdetermineswhatfeedstocksandrunvolumesareneededsoeachofthevariousprocesseswillyieldtherequiredvolumesandspecificationsofproducts,suchasgasoline,dieselfuelandfurnaceoil.Theheavy,black,bottomofthebarrelresidualremainingafterprocessingcanbesoldasasphaltorblendedwithlightermaterialsandsoldas"resid"(residualfueloil).
Petrochemicals
Petrochemicalsarenonfuelcompoundsderivedfromcrudeoilandnaturalgas.Theindustryhasbeenbuiltontheextremereactivityofthecarbonatom.Thefeedstocksforpetrochemicalplantsareprovidedlargelybyrefineriesandincludegases,naphtha,kerosene,andlightgasoil.Naturalgasprocessingplantsarealsoasourceoffeedstock,providingnaturalgas,ethaneandLPG(liquefiedpetroleumgas).
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Petrochemicalplantsaretypicallybuiltadjacenttorefineriestobeneartheirsourceoffeedstock.Also,thereoftenarebyproductstreamscreatedintheplantsthatcanbestbeutilizedbyreturningthemtotherefineryforprocessing.Infact,theboundarybetweenthetwotypesofplantoftenbecomesblurredasprogressiveintegrationofbothfluidstreamsandoperatingpersonneltakesplaceforincreasedefficiency.Asaresult,severalverylargerefining/petrochemicalcomplexeshavedevelopedaroundtheworld.
Petrochemicalprocessesare,ingeneral,muchsmallerthanrefineryprocesses,butthereareexceptionslikeverylargeethyleneplants.Thesametoolsareusedasinrefiningheat,pressureandcatalystsbut,unlikerefineries,inorganicchemicalsareusedinsomeofthereactions.
It'snothardtovisualizeafuturewherecrudeoilandnaturalgascouldbecomeinsuchshortsupplythatburninghydrocarbonsasfuelwouldnolongermakesense.However,itwouldstillmakesensetomanufacturepetrochemicalsbecausetheyextractsuchincrediblevaluefromthehydrocarbonmolecule.
ProcessTool
Whethercruderefiningorpetrochemicalprocesses,thetoolsusedarethesame.Theyare:Heat(distillation):toexcitethemoleculesPressure:toretardvaporizationCatalyst:toassistthereactionbutnotparticipateinit
References
TheabovestuffistheexcerptfromThePetroleumIndustry,ANontechnicalGuidebyCharlesF.Conaway,Tulsa,OklahomaPublisher.1999.
SimplifiedChainofValue
Chain Feedstock(input) Process ExamplesofYield(output)
Refinery Crudeoil
Heat,pressure,catalysts
Kerosene,lightoil(jetoil,gasoline,diesel),Naphtha,Benzene,LPG,HFO,Bitomen,Sulfur
Petrochemical Fromoutputofrefineries Ethylene,polymers,PVC,Polyethylene,Polypropylene
ChemicalsOutputfrompetrochemicalorfromothersources
Fibres
Equipment
Thefollowingsarecommonequipmentfoundintheoilandgasplant.Absorber:CollectorthatactivelyabsorbsthelightraysBoiler:ProvidesteamheatCompressors:Compressorsdothesameforgasstreamsaspumpsdoforliquidscreatingapressuredifferentialthatmovesthegasthroughthesystem.Itisusedtoinjectlowpressureassociatedgasintohighpressurepipelines.Columns:FordistillationDeaerator:ToremoveairDrum:AcylindricalmetalcontainerforstorageofliquidsFurnace:ProvideheatforcrackingMeters:Monitoringandcontrolmeterssenseflowratesandpressuresinvesselsandpiping,alerttheoperatororautomaticallytaketheneededaction.Nozzle:ExhaustducttocontrolfluidflowexitfromanenclosedvesselPipeline:Pipelinestransportforbothgasandliquids.Theyprovidetheconduitsfortransportingproducedfluidsto
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andthroughthefacility.Theyareconstructedbyweldingtogetherjointsofsteelpipe.Mostpipelinesareexternallypaintedandinsulatedforprotectionfromcorrosionandabrasion.Piperack:SupportpipelinesPressurevessels:Thelargecylindricalpressurevesselsseenineveryproducingfacilityareessentiallyenlargedsectionsofapipeline.Theenlargementallowsfluidvelocitytoslow,providingtheretentiontimenecessaryforthefluidstogravitysegregate.Gravitysegregationistheprimarymechanismusedtoseparateoil,waterandgas.Pumps:Pumpspressurizeliquids,creatingapressuredifferentialthatmovesliquidsthroughthesystemfromlowerleveltothehigherlevel.Reactors:Adeviceusedtoforceacontrolledreactionwithagivensubstance.Themostcommonreactorisanozonereactor,whichforceswaterthroughapressurizedcolumnofanairozonemixtureTanks:Tanksarelargevesselsusedforvolumestorageofoilorwaterortoprovideretentiontimeforgravitysegregation.Althoughstoragetanksarenotconstructedtocontainpressure,afewouncesofgaspressureisnormallymaintainedtoexcludeair.Tower:SameascolumnValves:Theyeitherblocking(openorclosed)orcontrol(throttling).
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