Section 3 Oil Processing System

8/22/2019 Section 3 Oil Processing System

1/91

OSX2 OPERATIONS MANUAL

PART 3 PROCESS TOPSIDE SYSTEMS

SECTION 3:OIL PROCESSING SYSTEM

SECTION3

OILPROCESSINGSYSTEM


2/91




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


3/91




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


4/91




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


5/91




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:


6/91




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.


7/91




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.


8/91




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


9/91




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


10/91




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


11/91




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)

Date post:	08-Aug-2018
Category:	Documents
Upload:	indurisiva
View:	213 times
Download:	0 times

Section 3 Oil Processing System

Documents