section 3 oil processing system
TRANSCRIPT
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OSX2 OPERATIONS MANUAL
PART 3 PROCESS TOPSIDE SYSTEMS
SECTION 3:OIL PROCESSING SYSTEM
SECTION3
OILPROCESSINGSYSTEM
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OSX2 OPERATIONS MANUAL
PART 3 PROCESS TOPSIDE SYSTEMS
SECTION 3:OIL PROCESSING SYSTEM
TABLEOFCONTENTS
1
INTRODUCTION............................................................................................................4
1.1 OVERVIEW..................................................................................................................4
1.2 SCOPE.........................................................................................................................4
1.3 RESPONSIBILITIES.......................................................................................................5
1.4 SAFETYPRECAUTIONSANDSYSTEMHAZARDS..........................................................5
1.4.1 SafetyPrecautions ........................................................................................ 5
1.4.2 SystemHazards............................................................................................. 5
2
SYSTEMDESCRIPTION................................................................................................11
2.1 INTRODUCTION........................................................................................................11
2.1.1 HPSeparation ............................................................................................. 11
2.1.2 LPSeparation.............................................................................................. 11
2.1.3 ElectrostaticDehydrator............................................................................. 12
2.1.4 ElectrostaticDesalter.................................................................................. 12
2.2 PROCESSDESCRIPTION.............................................................................................12
2.2.1 StartUp ...................................................................................................... 12
2.3 PROCESSTRAINDESCRIPTION..................................................................................13
2.3.1 HPSeparatorVT6201 ................................................................................ 13
Figure1 DesignLevelsforHPSeparatorVT6201 ..................................................... 14
2.3.2 Crude/CrudeHeatExchangerET6202A/B .................................................. 16
2.3.3 CrudeOilHeaterET6203A/B...................................................................... 17
2.3.4 LPSeparatorVT6202 ................................................................................. 18
Figure2 DesignLevelsforLPSeparatorVT6202...................................................... 18
2.3.5 CrudeOil
Pumps
PT6201A/B...................................................................... 21
2.3.6 DehydratorInletHeaterET6204A/B .......................................................... 21
2.3.7 ElectrostaticDehydratorVT6203............................................................... 22
2.3.8 ElectrostaticDesalterVT6204.................................................................... 24
2.3.9 CrudeOilCoolerET6205A/B ...................................................................... 26
2.4 ASSOCIATEDSYSTEMS..............................................................................................27
3 SYSTEMOPERATION...................................................................................................29
3.1
CONTROLPHILOSOPHY
............................................................................................
29
3.1.1 Duty/StandbyPumpControls...................................................................... 30
3.1.2 SimpleControlLoops .................................................................................. 30
3.2 SYSTEMCONTROLLOOPS.........................................................................................31
3.3 PRESTARTCHECKS...................................................................................................33
3 3 1 Valve Position Checklist 36
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OSX2 OPERATIONS MANUAL
PART 3 PROCESS TOPSIDE SYSTEMS
SECTION 3:OIL PROCESSING SYSTEM
3.6 BLOWDOWNANDMANUALVENTING.....................................................................73
3.6.1 Blowdown ................................................................................................... 74
3.6.2 ManualVenting .......................................................................................... 74
3.7 SYSTEMTRIPS...........................................................................................................74
3.8 ROUTINECHECKS......................................................................................................76
3.9 OIL,WATERANDGASSAMPLING.............................................................................78
3.9.1 SamplePoints ............................................................................................. 79
Figure3 SamplePoint LiquidwithCooling.............................................................. 79
Figure4 SamplePoint HighPressureGas ............................................................... 80
Figure5 SamplePointLowPressureLiquids .......................................................... 80
3.10
TROUBLESHOOTING.................................................................................................
81
4 OPERATINGDATA.......................................................................................................83
4.1.1 SeparatorVesselInternals .......................................................................... 86
4.1.2 ElectrostaticTreaterInternals..................................................................... 87
5 REFERENCES...............................................................................................................87
5.1 REFERENCEDOCUMENTS.........................................................................................87
5.2
REFERENCEDRAWINGS
............................................................................................
87
ILLUSTRATIONS
Figure1 DesignLevelsforHPSeparatorVT6201 ..................................................... 14
Figure2 DesignLevelsforLPSeparatorVT6202...................................................... 18
Figure3 SamplePoint LiquidwithCooling.............................................................. 79
Figure
4Sample
Point
High
Pressure
Gas............................................................... 80
Figure5 SamplePointLowPressureLiquids .......................................................... 80
Figure6 SystemSchematic ....................................................................................... 89
Figure7 EquipmentLocations................................................................................... 90
Figure8 TypicalInternalsforElectrostaticTreater.................................................. 91
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OSX2 OPERATIONS MANUAL
PART 3 PROCESS TOPSIDE SYSTEMS
SECTION 3:OIL PROCESSING SYSTEM
1 INTRODUCTION
1.1 OVERVIEW
RefertoPFDDTT92027&DTT92028
ThemaincomponentsoftheOilProcessingSystemreferredtointhisprocedureare
accommodatedinmodules1,2,andupperdeck,andcomprisethefollowing:
TagNo TopsideEquipment Module
VT6201
HP
Separator.
M01
ET6202A/B Crude/CrudeHeatExchanger. M01
ET6203A/B CrudeOilHeater. M01
VT6202 LPSeparator. M01
PT6201A/B Crude OilPumps. M01
ET6204A/B DehydratorInletHeater. M01
VT6203 ElectrostaticDehydrator. M02
VT6204 ElectrostaticDesalter. M02
ET6205A/B CrudeOilCooler. M01
AT6210 OilFiscalRundownMeter. M09
Theoil
process
train
as
listed
above
is
asystem
in
which
live
crude
oil
is
stabilized
by
theseparationofoil,gasandproducedwaterinathreestage,threephaseprocess.
Finally the processed crude is pumped into the vessels cargo storage tanks via a
crudeoilfiscalmeteringunit,fromthesetanksthedeadcrudeoilisthenoffloadedto
atradingtanker.
GasassociatedwiththewellfluidsisflashedoffintheHPseparator,LPseparatorand
produced water flash vessel. HP separator gas is dried and compressed prior to its
usagefor
gas
lift
and
fuel
gas.
Produced
gas
from
the
LP
separator
is
compressed
by
theboostergascompressionsystempriortoroutingtothemaingascompressorfor
gasliftorexport.Anyexcessgascanbeflaredalthoughaminimumflaringpolicyisto
beadheredto.
Producedwaterfromtheseparatorsisinitiallyseparatedfromthecrudeoilbygravity
and finally by an electrostatic coalescing process before being degassed cooled de
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PART 3 PROCESS TOPSIDE SYSTEMS
SECTION 3:OIL PROCESSING SYSTEM
1.3 RESPONSIBILITIES
Onlythefollowingpersonnelshouldusethisprocedure:
Productionoperationspersonnelqualifiedtooperatethefacilities
Personneltrainingunderthesupervisionofaqualifiedperson
1.4 SAFETYPRECAUTIONSANDSYSTEMHAZARDS
1.4.1 SafetyPrecautions
The following list of safety precautions are derived from SIDVIN safe working
practisesintendedtoprotectoperatingpersonnel:
TheSIDVINspecifiedpersonalprotectionequipmentmustbewornatall
timeswhenworkingontheprocesstrain.
Inthevicinityofanyprocessorequipmentproducinghighnoiselevels(asindicatedbywarningsigns)approvedhearingprotectionmustbeworn.
Allisolations
on
aprocess
or
utility
system
must
be
performed
in
accordance
withcurrentSIDVINmechanicalisolationspolicy. Positiveisolationwillbe
viatheuseofblindsordoublevalvearrangements. ThePermittoWork
systemshallensurethatappropriateprecautionsinrespectofisolationand
monitoringareimplementedformaintenanceactivitiesofthissort.
Noequipmentmodificationsshallbemadewithoutpriorauthorisationand,
ifapplicable,ariskassessmentshouldbecarriedout.
Allwork
on
electrical
equipment
must
be
carried
out
by
suitably
qualified
personnelandinaccordancewithSIDVINisolationstandards.
PriortotheissueofaWorkPermitforrepairorintrusivemaintenancework(s)depressurisingshallbeconfirmedusingacertifiedpressuregauge
andvent/drainvalves.
1.4.2 SystemHazards
Safety
protection
in
the
form
of
automatic
sensing
systems
and
trips
have
been
provided throughout the FPSO systems, but operators must make every effort to
ensure that the process is operated within its design parameters and that process
upsetsdonotoccur.
TheprimaryhazardsassociatedwiththeOilProcessingsystemare:
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PART 3 PROCESS TOPSIDE SYSTEMS
SECTION 3:OIL PROCESSING SYSTEM
1.4.2.1OperationalHazards
Note:Mostofthepotentialhazardsandproblemsdetailedbelowwillinitiateaunitor
processshutdownbeforethesituationbecomescriticalandother itemswill
havebeenengineeredoutbytheinitialdesign. However,operatorsmustbe
awarethatthesehazardsexistandshouldnotrelyentirelyonsafetytripsto
preventthemoccurring.
The following list of potential process train hazards and upsets is intended as
guidance to what can occur in the event of instrument malfunction, mechanical
failure,oroperatorerror:
Processequipmentoverpressure.
Livecrude/gasdischargeintotheproducedwatersystem.
Gasdischargeintothecrudehandlingsystem.
Crudeoilorwatercarryoverintothegashandlingsystem.
ContactbetweengasorwaterandHVelectrodesinelectrostatictreater.
Crudeoilpumpssealleakage.
Blockagesin
crude
oil
pump
suction
line.
Crudeoilpumpdischargelineblockage.
Backflowfromelectrostatictreatertocrudepumps.
Crudeleakagefromplate&gasketheatersET6203A/B.
Uncontrolleddischarge/leakageofHP/LPgastoflare.
Producedwatercarryoverintocrudeoilflow.
Heatingmedium
leakage
from
heaters
ET6203A/B.
Inaccuratefluidandgasmetering.
a) ProcessEquipmentOverpressure
All items of process equipment are fitted with one or more pressure safety valves
that relieve pressure to vent automatically. In addition each separator vessel is
equippedwith
ahigh/high
pressure
sensor
that
will
initiate
aunit
shutdown.
CAUTION: OPERATORS MUST BE AWARE THAT DURING STARTUP, FAILURE TO
CARRY OUT THE REQUIRED PRESTART CHECKS COULD RESULT IN
OVERPRESSURINGSECTIONSOFTHEPROCESSTRAINDUETOAFAILURE
TOOPENDESIGNATEDLINEVALVES.
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PART 3 PROCESS TOPSIDE SYSTEMS
SECTION 3:OIL PROCESSING SYSTEM
LOCATION TAGNO. SIZE SETTING
Topmounted
gas
relief
T62
PSV
0041C
8
x10
15.7
barg
LPSeparatorVT6202
Referto:DTT62009TopsideLPSeparator
Topmountedgasrelief
Topmountedgasrelief
T62PSV0061A
T62PSV0061B
3x4
3x4
15.0barg
15.0barg
DehydratorInletHeaterET6204A/B
Referto:
DTT62001
Topside
Dehydrator
Inlet
Heater
TopmountedgasreliefET6204A
TopmountedgasreliefET6204B
T62PSV0010
T62PSV0011
1x2
1x2
15.0barg
15.0barg
ElectrostaticDehydratorVT6203
Referto:DTT62006TopsideElectrostaticDehydrator
Topmountedgasrelief
Topmounted
gas
relief
T62PSV0021A
T62PSV
0021B
3x4
3x4
15.0barg
15.0barg
ElectrostaticDesalterVT6204
Referto:DTT62007TopsideElectrostaticDesalter
Topmountedgasrelief
Topmountedgasrelief
T62PSV0031A
T62PSV0031B
3x4
3x4
15.0barg
15.0barg
CrudeoilcoolerET6205A/B
Refer
to:
DTT62003
Topside
Crude
oil
cooler
Coolingmediuminlet T25PSV0017
T25PSV0018
1x2
1x2
15.0barg
15.0barg
Note:ThedesignpressureoftheLPSeparatorisconsistentwiththeHPSeparatorthe
relief valves on the LP Separator have been set at 15.0 Bar to provide
protectionfortheCrudeOilHeaterET6203ofwhichthecoldsideisonlyrated
to15.0
Bag.
b) LiveCrude/GasDischargeintotheProducedWaterSystem
Thesecircumstancescanbecausedbythefollowingprocessmalfunctions:
Interfacelevelcontrolfailure.
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PART 3 PROCESS TOPSIDE SYSTEMS
SECTION 3:OIL PROCESSING SYSTEM
Interface and general level control problems will also occur if the antifoaming
chemicalinjectionratesareinsufficientorexcessive.
Topreventtheaccidentaldischargeof livecrude intotheproducedwatersystemalow/lowleveldetectedinthereceptionsectionofeitherseparatorvesselwillcausea
unitshutdown. Refertopara.3.6SystemTrips.
The vessel slop tanks have sufficient capacity both liquid and gas handling to cope
withashorttermaccidentalcrudedischarge.However,thisisanundesirableprocess
upsetthatoperatorsshouldtakecaretoavoid.
c) GasDischarge
into
the
Crude
Handling
System
Afailureofthe levelcontrolsystemsineithertheHPorLPseparationvesselscould
result ina lossofcrudeoil levelandgasenteringthecrudehandlingsystem. Inthis
eventadualfunctionhigh/high,low/lowlevelsensorintheoilsectionaftertheweir
willcauseaunitshutdown.
d) CrudeOilorWaterCarryoverintotheGasHandlingSystem
Inthe
event
that
ablockage
occurs
to
either
the
water
or
crude
vessel
outlets,
failure
toshutdown quickly enoughcould result incrude froma HP and/or LPseparation
vesseloverflowing intothegashandlingandflaresystems. Blockagescouldbeasa
resultofoperatorerrororlinevalveproblems.
Topreventthisoccurring,adual functionhigh/high, low/low levelsensor in theoil
sectionaftertheweirwillcauseashutdownandclosureofprotectiveSDVs.
Oilcarryovercouldalsooccurintheeventofasuddensurgeorslugofflow,possibly
causedby
opening
awell
too
quickly.
The
liquid
slug
so
created
could
exceed
the
crudedesignhandlingcapacityofoneormoreoftheseparationtrainvessels.
e) ContactbetweenGasorWaterandHVElectrodesinElectrostaticTreater
AmajorfallintheliquidlevelwithintheElectrostaticTreaterwouldresultintheHV
electrodes being exposed to gas and oil vapour. Level switches T62LS0020/0021
protectagainstthisbyswitchingoffthepowertothetransformerswhena low/low
levelissensed.Inadditionbothahigh/highandalow/lowwaterlevelwillalsocause
ashutdown.
f) CrudeOilPumpSealLeakage
Failureofacrudepumpsealcouldresultincrudespillagetothelocalarea.Theseal
leakdetectionsystemofeachpumphasahighpressureswitchwhichwillcausethe
t t ti ll h td h ld th l l k
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PART 3 PROCESS TOPSIDE SYSTEMS
SECTION 3:OIL PROCESSING SYSTEM
A strainer in each pump suction line will trap sand and other foreign matter thus
preventing pump damage. However, these should be checked for blockages in the
eventof
adetected
low
suction
pressure.
h) CrudeOilPumpDischargeLineBlockage
A downstream blockage will cause the pump discharge pressure to rise and a unit
shutdowntooccurviaahigh/highpressuresensor.However,crudepumpsareofthe
centrifugaltypeandcanoperateforshortperiodsagainstacloseddischargevalve.
i) BackflowfromElectrostaticTreatertoCrudePumps
Checkvalvesare locatedadjacenttotheelectrostatictreaterbottomentrypoint in
order to prevent backflow. Check valves are also sited in each pump discharge.
Failureofanyoneofthesecheckvalveshasthepotentialtoallowbackflowofcrude
fromthetreatervesselwhilstthepumpsareshutdown.
j) CrudeLeakagefromPlate&GasketHeatersET6203
Plate and gasket heat exchangers are used for heating live crude exiting the
productionseparator.
Should
the
exchanger
distort,
the
rubber
seals
incorporated
in
thematricesandpipeworkconnectionsmayfailandallowcrudeoiltobeexpelled.
Themostlikelycauseofsuchanoccurrencewouldbeexposureoftheexchangertoa
suddenpressureor temperaturechange.Protectivebarriershavebeenprovided to
protectpersonnelagainstfluidsprayfromaleak.
CAUTION:WHENREASSEMBLINGPLATEANDGASKETEXCHANGERS,SOASTOAVOID
DAMAGETOTHEEQUIPMENT,THESUPPLIERSRECOMMENDEDTORQUE
SETTINGSMUST
NOT
BE
EXCEEDED.
k) UncontrolledDischarge/leakageofHP/LPGastoFlare
In the event that the HP separator pressure control valve should fail in the open
position,HPgaswilldischargetotheflareheadercausingalossofcrudedrive. The
effectofthiswillbearisinglevelinthevessel,liquidcarryover,pressurealarmsand
ultimatelyahigh/highleveltrip.
l) HeatingMedium
Leakage
from
Heaters
ET6203
Aplatefailurewithintheplate&gasketheatercouldresultinanuncontrolledrelease
ofhotwatertoatmosphere.Amechanicalbarrierhasbeenprovidedtocontainthis
typeofleakageandprotectpersonnel.
!HAZARD
Haz 51
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SECTION 3:OIL PROCESSING SYSTEM
Note:Ultrasonicflowmeters have a different operatingprinciple to turbinemeters
and consequently thepresence of gas is immediately detected. However,
turbineflowmeters
are
prone
to
inaccuracy
and
will
indicate
a
disproportionateincreaseinflowwheregasispresent.
Inthecaseofgasmetering,excessive foaming inthevesseland/or liquidcarryover
will cause fluids to appear in the flow orifice lines thus causing inaccurate sensing
pressures.
AccessplatformsaboveHPandLPseparators
Theaccess
platforms
above
the
HP
and
LP
separators
have
only
one
escape
route
and
thereforetheseshouldonlybeusedwhenthereisaclearoperationalrequirement.
!HAZARD
Haz 214
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OSX2 OPERATIONS MANUAL
PART 3 PROCESS TOPSIDE SYSTEMS
SECTION 3:OIL PROCESSING SYSTEM
2 SYSTEMDESCRIPTION
2.1 INTRODUCTION
RefertoP&IDDDT62001/2/3/4/5/6/7/8/9110andFigure6
Theprimaryobjectiveoftheseparationtrainandassociatedequipmentistoprocess
and stabilize live crude produced from subsea wells in order to meet storage and
exportspecificationsforBS&W,temperature,salinityandvapourpressure.Theseare
listedbelow.
BS&W(ASTM
D4377/4007)