Lecture - Hydrocabon feld processinf overview.pdf

work describes the hydrocarbon processing of oil water and gas

1. PE 358
PETROLEUM PRODUCTION ENG II
DR. K. SARKODIE
OVERVIEW OF OIL FIELD
PROCESSING

2. ThisLecture
•Reservoirfluids
•Productionmonitoring
•Exportspecifications
•Productionfacilities
•Oilprocessing
•Waterprocessing
•Gasprocessing
•Flowassurance:
•Mineralscaledeposition
•Organicdeposition
•Hydrateformation
•MicrobialactivityandH
2S
•Offshoreproductionfacilities
2

3. ProductionFacilities
RESERVOIRFLUID
HPSEPARATOR
25BAR
MPSEPARATOR
18BAR
EXPORTOIL
LPSEPARATOR
12BAR
WATER
EXPORTGAS
HPCOMPRESSION
MPCOMPRESSION
LPCOMPRESSION
GASLIFT
FUELGAS,FLARE
DEHYDRATION
40BAR
130BAR
3

4. ProductionFacilities
Themainpurposeistheseparationofoil,waterand
gasandtheremovalofimpurities.
•Oilprocessing
•Waterprocessing
•Gasprocessing
4

5. ProductionMonitoring
•Dailyproductionismeasuredbymonitoringthevolumesof
oil,gasandwaterproducedovera24hourperiod.
•Cumulativeproductioniscollatedmonthlyandyearlyalong
withfiscalmetering.
•Pressureandtemperatureismeasuredatkeylocationsin
theproductionprocess.
•Downhole
•Wellhead
•Process
•Export
•Mostproductionoperationsareequippedtomonitor
continuously,providingadesktopread-outofkeydata.
5

6. ExportSpecifications
•TypicalOilExportSpecification:
•TrueVapourPressure(TVP)14.5psiaat85°F
•BasicSedimentandwater(BS&W)2%maximum
•Typically65°Fwaxformationtemperaturemaximum
•TypicalGasExportSpecification
•WobbeIndexof47.2to51.41MJ/scm
•Exportatallpressuresupto172.4barg
•Temperature50°Cmaximum
•WaterContentof3lb/mmscfmaximum
•Cricondenbarof105bargmaximum
•H
2Scontentof500ppm(mol)maximum
•CO
2contentof22mol%maximum
•Freeofcontaminants
•Waterforoverboard
•Lessthan10mg/kgoilorppm(mass)
6

7. OilProcessing
•Initialseparation:Oil,gasandbasicsedimentandwater
(BS&W)areseparatedbygravitysettling,duetotheir
differentdensities.
•Stabilisation:wherelighterendsareremovedbydropping
thepressure–movingthemintothevapourphaseand
loweringtheTrueVapourPressure(TVP).
•Numberofseparationstages:decidedbytheflowing
wellheadpressureP
whorFWHPandthequalityofgasand
oilrequired.
➢Thehigherthenumberofstagesthehigherthequality
7
FWHPBaraNo.SeparationStages
0-20 1or2
20-70 2or3
Over70 3or4

8. OilProcessing
•Electrostatics:utilisespolarityofwatermoleculestoassist
dropletgrowthandhenceimproveliquid/liquidseparation.
•Saltremoval:saltisfoundintheentrainedwaterdropletsin
theoil.Toremovethesalt,theoiliswashedwithfreshwater,
whichisthenseparatedfromtheoilusinganelectrostatic
coalescer.
•Chemicalinjection:
•Separationcanbeaidedbyademulsifierorantifoam
•Heavyendscanbekeptintheliquidphasebyawax
inhibitor
➢TypicalOilExportSpecification:
➢MaximumlimitofBS&Wandsalt
➢MaximumlimitoflighterendsorTVP
➢Maximumwaxformationtemperature
8

9. DisposalWaterProcessing
•Contaminantscanberemovedby:
•Settling
•Filtration
•Othermeans
•Watercanbeputthroughahydrocyclonetoreduceoil
content.
•Usescentrifugalforcetoseparateoilfromwater
•Basedondensitydifference
➢Disposalspecification:
➢Maximumlimitofoilinwater(<30ppm)
➢Removalofcontaminantsthatdamage
theenvironment
9

10. DisposalWaterProcessing–ProcessDiagram
ProductionSeparator
Choke
Hydrocyclone
Degasser
to flare
500 -1000 ppm
<40 ppm
<30 ppm
10

11. ReinjectionWaterProcessing
•Filtrationtoremovesolids
•O
2isremovedusinganO
2scavengerandsuitablecontactor
•Biocide(Sodiumhypochlorite)injection–theseawateris
continuallytreated,thefreechlorineactsasthebiocide,which
killsthebacteria.
•Microbialactivity:aerobicandanaerobic.
•Sulphate-reducingbacteriametaboliseusingsulphate
ratherthanoxygen.
•Asaresult,theyproduceH
2S,makingthereservoirsour.
•Scaleispreventedusingascaleinhibitor
➢Re-injectionspecification
➢Maximumlimitofoxygen
➢Removalofbacteria
11

12. GasProcessingorHandling
•Separation:Gasandoilareseparatedbygravitysettling,
duetothelowerdensityofgascomparedtooil.
•Cooling-scrubbing-compression:Heavierendsandwater
areremovedproducingaleanergas.
•Dehydration:thegascanbedehydratedusing:
•Glycol(e.g.ethyleneglycol)andasuitablecontactor.
•Molecularsieveadsorption
•Desiccantdehydration
12

13. GasProcessingorHandling
•Sweetening:H
2S(sourgas)andCO
2(acidgas)canbe
removedusing:
•Aparticularamine(e.g.MethylDiEthanolAmine,
MDEA)–andasuitablecontactor.
•Molecularsieveadsorption
•Membraneseparation
•Solidscanberemovedbyfiltration.
➢TypicalGasExportSpecification:
➢Maximumlimitofheavierends
➢Maximumlimitofwater
➢MaximumlimitofCO
2,H
2Sandcontaminants
13

14. GasProcessingorHandling-ProcessDiagram
Gasfrom
Separators
1stStage
Compression
2ndStage
Compression
Export
Compression
Dehydration
Column
LeanGlycol
RichGlycol
Export
GasLift
Re-injection
NGLs NGLsNGLs
•Compresstoexportgastomarket
•Reinjectforreservoirsupport
•Reinjecttoimproverecovery
•CompresstorecovervaluableNGLs
•Useasfuel
•Flare
14

15. Cooling-Scrubbing-Compression
NGLstoseparation
Scrubber
•Otherwiseknownasa“gascompressiontrain”
•Coolingthegascondensesoutwaterandheavierends.
•Theliquidisremovedbythescrubber.
•Thegasisthencompressedincreasingthepressureand
consequentlyincreasingthetemperature,whichisknown
asthe“Joule-Thompsoneffect”.
tonextstagecompression/
dehydration/sweetening
CompressorCooler
Saturatedvapour
15

16. Dehydration
Glycolabsorptioncanbe
usedtodehydrategasto
pipelinespecifications:
➢Intheliquidstate,
watermoleculesare
highlyassociated
becauseofhydrogen
bonding.
➢Thehydroxylgroupsin
glycolsformsimilar
associationswith
watermolecules.
➢Thisexplainswhy
glycolsaresuchgood
absorbersofwater
16

17. SweeteningandH
2S
HydrogenSulphide(H
2S)
•Presentahazardtopeople
andtheenvironment.
•Corrodesmetal.
•Reducethevalueofthe
crudeandgas.
•Anamine,e.g.MDEA,is
usedtoremoveH
2Sfrom
thesourgasstream.
•TheMDEArapidlyabsorbs
theH
2Sandmustbe
heatedtoreversethe
absorption.
•Acidgasisincineratedfor
safedisposal.
17

18. FlowAssurance
•(Flowregimesandconditions)
•Mineralscaledeposition
•Organicdeposition
•Hydrateformation
•MicrobialActivityandH
2S
•Corrosion
18

19. ReservoirFluidNon-hydrocarbonComponents
•BS&W–BasicSediment&Water
•Nitrogen,N
2
•Oxygen,O
2
•Hydrogen,H
2
•Helium,He
•CarbonDioxide,CO
2
•HydrogenSulphide,H
2S
•Mercaptans,C
2H
2SH(ethyl-mercaptan)
•Metals:
•Nickel,Ni
•Copper,Cu
•Zinc,Zn
•Iron,Fe
•Vanadium,V
•Mercury,Hg
19

20. ProducedWaterAnalysis
•Thistableshowsanexample
oftheionsfoundinthe
producedwaterfroma
reservoir.
•Theconcentrations(mg/L)will
varyconsiderablyfordifferent
reservoirs.
•Cancausescale,corrosion
andblockagesinthe
productionsystem.
•Environmental&Health
issueswithdisposal.
Components mg/L
Cations
Sodium 9110
Potassium 143
Calcium 181
Magnesium 16
Barium 40
Strontium 11
TotalIron 2
DissolvedIron 0.2
Anions
Chloride 13550
Sulphate 120
Bicarbonate 640
Carbonate 0
Hydroxide 0
Otherions
Boron 22
Li2th0ium 4

21. MineralScaleDeposition
Scaledepositioniscontrolledbychemicalsknownasscaleinhibitors.
•Calciumcarbonate-Calciteinhibitorsareused.Thedepositscanbe
dissolvedbyacid.
•Bariumsulphate-baritedepositsusuallyoccurdeepinthewelland
surroundingreservoir.Oncethedepositsformtheycannotbeeasily
removed,sopreventionisbetterusinganoperationcalledascale
squeeze.
Commonscales:
Calciumcarbonate
Bariumsulphate
Calciumsulphate
Strontiumsulphate
CaCO3
BaSO4
CaSO4
SrSO4
21

22. CalciteScalePrediction
50
Scaledeposition
0
100
150
200
250
40 45 50 55 60 65 70 75 80 85 90
P
r
ess
u
r
e
(
b
a
r
)
Temperature(
oC)
Caciteenvelope
Caciteenvelope
Noscaledeposition
22

23. OrganicDeposits-Wax
•Theheavycrudeoilscontainhigherproportionsoflongchainalkanes.
•WaxAppearanceTemperature-Longchainheavier‘ends’precipitate
assolidwax.
•Pourpoint–lowesttemperatureatwhichtheoilcanbepouredat
atmosphericconditions.belowthispointthewaxcanformagellike
structurewiththeoil
•Waxdepositscanbuildupintubularsandflowlinesuntilablockage
occurs.
•Chemicals,knownaswaxinhibitorscanassistinkeepingthewaxy
solidssuspendedinthecrudeoil.
•Heatingcanmeltthewaxintosolutiontoremoveblockages.
•Mechanicalmeanscanbeusedtoremovethedeposits;forexample
pigging.
23

24. OrganicDeposits-Asphaltenes
•Soidsformedfromnaturallyoccurringhetero-cycloalkanes(cyclicwith
O,N,S,etc.inchain).
•Theyareablackpowderysubstance-unlikewaxsolidstheyarenot
crystalline
•Theyaresolubleinaromaticsolvents
•Theycanberemovedthroughmechanicalmeans
•Asphalteneswilltendtoprecipitateoutofthecrudeoilwithcomposition
change,duetopressureortemperature.
24

25. HydrateFormation
•Methanehydrate,shownbelow,isanice-likesolidthatformsatlow
temperatureandhighpressurewhenmethaneisincontactwithwater.
•Thesolidhydratecanblockaflowlineinashortperiodoftime(hours).
•Theblockagewillmeanlossofproductionuntilitisremoved.
25

26. MethaneHydratePrediction
200
180
160
140
120
100
80
60
40
20
0
‐25 ‐20 ‐15 ‐10 ‐5 0 5 10 15 20 25
P
r
ess
u
r
e
(
b
a
r
a)
TemperatureC
HydrateCurveforWellL-3ProducedWater
Hydrateregion
Nohydrate
HydrateCurve
26

27. HydrateMonitoringandPrevention
•Monitorthewatercontentforgasexportlines
•Operateoutsidethehydrateformationregionifpossible
•Insulationshouldbeemployedtoremainoutsidethehydrate
formationregion
•Hydratesaremostlikelytoformdownstreamofchokevalvesand
insubseapipelines.Problemsareamplifiedduringstart-upand
shutdown.
•Inhibitorinjectionshouldbeprovidedforstart-upandshutdown
•Carefullyselectinhibitorinjectionpointstoensureallareascan
beprotected/inhibited
•Atthereceptionfacilityagoodindicationofhydrateformationin
thetransportationsystemislossofwaterproduction
•Gasdehydration
27

28. MicrobialActivityandH
2S
MicrobialActivity
•Thewaterinjectionprocessisaffectedbymicrobialactivity:aerobicand
anaerobic.
•Themostcommonbacteriaintheoilfieldaresulphate-reducingbacteria
(SRB),whichmetaboliseusingsulphateratherthanoxygen.
•Asaresult,theyproduceH
2S.Whenthishappensthereservoirissaid
tobesour.
•Biocide(Sodiumhypochlorite)–theseawaterinjectioniscontinually
treated,thefreechlorineactsasthebiocideandattacksthebacteria.
HydrogenSulphide(H
2S)
•Presentahazardtopeopleandtheenvironment.
•Corrodesmetal
•Reducethevalueofthecrudeandgas
•H
2SiscontrolledbyaddinganH
2Sscavengertothegasphase

29. TypesandEffectsofCorrosion
Corrosionexistswherewaterispresentincombinationwitharedoxsource
suchasoxygenortheacidgasesCO2andH2S.
Types:
•Uniform
•Localised–pittingandcrevice
•Galvanic–galvanicseries(dissimilarconductors)
Effects:
•Holesindownholetubingandsurfacepipelinesleadingtolossof
containment(oilspill).
•Reductionofpipewallthicknessleadingtorupture.
•Solidmetalliccorrosionby-productscanbreakawaytoformblockages
intheprocesssystemorreservoir.
➢Alloftheabovecanbehazardoustopersonnel,damagingtothe
environmentandcostlytoputright.
➢Controlofcorrosionisbetterthantryingtocuretheafter-effects.
29

30. EffectsofCorrosionandProtectionTechniques
Protectionagainstcorrosionis
providedby:
•Choosingcorrosionresistant
alloysforthedownholetubing.
•Addingacoatingtothe
carbonsteelsurface.
•Injectingchemicalsknownas
corrosioninhibitorsintothe
producedfluids.
30

31. Jackup Semi-submersibleFixedplatform
FloatingProductionStorage
OffshoreProductionFacilities
31
Offloading(FPSO)Vessel

32. OffshoreProductionFacilities–FixedPlatform
•Standsonsteelandconcretelegsdrivenintothesea-bed.
•Thestructureconsistsofmultiplesteeldecksabovesealevel.
•Platformsaremanned(requireaccommodation)orunmanned.
•Fixedplatformsareeconomicinwaterdepthsto500m;thecapital
costisveryhigh.
•Costeffectiveforlonglifetimedevelopments(greaterthan20years).
•Theycanactashubsorproductioncentresforproductionfrom
neighbouringsatellitefields.
•Wellscanbedrilledandcompletedfromtheplatform.
•Thisgivesaccessibilitytothewellsforfutureinterventionneeds.
•Fixedplatformsareresistanttoseaconditions,verystableinbad
weather.
32

33. TheE11Hubinvolvesthedevelopmentof
shallowsatellitefieldswithapprox.500million
barrelsofoilequivalentofreservesanddesigned
toproduce1,650MMSCUF/dofgas.
ProductionPlatformCluster,E11Hub,Malaysia
33
(reproducedwithpermission)

34. ProductionFacilities–CutterTowerPlatform
Shell’sCutterTowerPlatform
(southernNorthSea),exports
gastotheonshoreBactonGas
Plant,120kmaway.
Plateauproductionisexpected
tobe3millionscf/d.Lifeoffield,
15years.
NotethisisaNUI–anormally
unmannedinstallation(common
forthegasfieldsofthesouthern
NorthSea).
Maintenanceeverytwoyearsby
ajack-uprig.
34
(reproducedwithpermission)

35. Floating(Semi-Submersible)ProductionFacility
•Consistsofasteelstructure,usuallywithlegsorcolumnssupported
bybuoyancychambers.
•Theplatformisanchoredintopositionontheseabed,smallerunits
canusedynamicpositioningmotors.
•Theplatformcanberelocatedusingtug-boats.
•Theseplatformsareeconomicinwaterdepthsto3000m.
•Thecapitalcostishighbuttheplatformcanberelocated.
•Suitableforshortlifedevelopments(10-15years).
•Resistanttoseaconditions-thedecksareabovesealevelso
reasonablystabletobadweather.
•Limiteddeckspacesomayrequireinterventionvessels.
•Drillingcarriedoutbyseparatefacility.
35

36. ProductionFacilities–SPARPlatform
Shell’sPerdidoSparPlatform(Gulfof
Mexico)–setawaterdepthrecord
(2450m)foranoffshoredrillingand
productionplatform.Designedto
process130000bopd.22vertical
wellsontheSpar,and13tie-backs
Thelargecylindricalcaissonacts
asabuoyancychamber
36
(reproducedwithpermission)

37. ProductionFacilities–BrutusPlatform
Tensionlegplatform-locatedinGreenCanyon
Block,GulfofMexico,in900mwaterdepth.Peak
production100000bopdand150MMscuf/dgas
37
(reproducedwithpermission)

38. FloatingProductionStorageOff-LoadingFacility
•Usuallyasteelhulledstructurebasedonatankerdesign.
•TheFPSOisasea-worthyvesselwithdriveunits,maintainedon-site
byanchorsanddynamicpositioning.
•Thehullislargelyusedforoilstoragetanks.
•Themultipledeckscontaintheproductionfacilities.
•Thesevesselsareeconomicforshortlifedevelopments(10-15
years).
•Thecapitalcostisrelativelylow.
•Drillingoperationsarehandledbyaseparatefacility.
•Oilstoragetakesplaceinthehulltanksofthevessel.
•Deckspaceismorelimitedthaneitheroftheaboveplatformsso
subseawellinterventionsrequireasupportvessel.
•Duetowavemotion,theconnectiontotheriserrequiresaspecial
swivelhousingknownastheturret.
38

39. FPSO,BongaField,Nigeria
•Shell’sBongadevelopment,
120kmoffthecoastof
Nigeria,isinwaterdepthsof
approx.1000m.
•Storagecapacity2MMbbl.
•Maxdesignproduction
225000bopdand
150MMSCUF/dgas.
•Oilisoff-loadedtoshuttle
tanker.
39
(reproducedwithpermission)

40. FPSO,BongaField,Nigeria
40
(reproducedwithpermission)

41. Deepwatermilestones
41

42. SubseaProductionFacilities
42

43. Review
•Reservoirfluids
•Productionmonitoring
•Exportspecifications
•Productionfacilities
•Oilprocessing
•Waterprocessing
•Gasprocessing
•Flowassurance:
•Mineralscaledeposition
•Organicdeposition
•Hydrateformation
•MicrobialactivityandH
2S
•Offshoreproductionfacilities
43