techniques to maximise oilfields production in the ... › wp-content › uploads › ...v excess...
TRANSCRIPT
Techniques to Maximise Oilfields ProductionIn The Republic of South Sudan
By:Eng. Salah H. WahbiChairman & Founder
Wahbi Consulting Services Co. Ltd.
PlanstoincreaseProductionRates
Planstoincreaseproductionratecanbecategorizedintotwomainareas:
A)ShorttermPlans.
A)MediumandLongtermPlans.
PlanstoincreaseProductionRatesA)ShortTermPlans(Workover)
Workoveroperationsareusedtosolve:
1. Lowreservoirpermeability.
2. Formationdamage.
3. Waterproduction.
4. Casingdamage.
PlanstoincreaseProductionRatesB)MediumandLongTermPlans
Mediumandlongtermplanscanbecategorizedas:
1. IOR(improvedOilRecovery).2. EOR(EnhancedOilRecovery)
PlanstoincreaseProductionRatesB)MediumandLongTermPlans(IOR)
IORincludes:• Infillwells.• WaterInjection.• ArtificialLift.
PlanstoincreaseProductionRatesB)MediumandLongTermPlans(EOR)
EORisconsideredatertiaryrecoverymethod.Itismainlyafterthemobilityrelationshipbetween
waterandoilEORinclude:a) Polymerflooding.b) Surfactants&alkalineinjection.c) Thermalmethods.d) Miscibleflooding(CO2)
A)ShortTermPlans(Workover)
SummaryofCommonProblems&WorkoverOperations
Excessive Water
Production
Squeeze & Re-perforating
Water Shut Off by Plugs
Chemical Water Shut Off
FACTORSINFLUENCEWATERINFLUXTherearemanyfactorsthatcaninfluencewaterinflux:1]Geological
SizeofstructureanditslocationRelativelythinupperlayerswithlateralvariationThinshalebreakwhichwilleasilyallowchanneling
2]WellLocationUpdip/DownorCrest/Flank
3]DriveMechanismStrongorweakwaterdrive
4]Oil-WaterContactBottomoredgewater
5]ThicknessofNetPay6]OperationalParameters
PressuredrawdownPumpfrequencyChokesize– duringtesting.
7]CompletionintervalStandoffOWC
WaterProductionMechanisms
(Curve 1) :- Completion Into Water and theproblemof fresh water resistivity.- Channel behind Casing (weekcurrent behind)(Curve 2) :- CasingLeaks- Channel behindCasing- StimulationOut of Zone- Barrier Breakdown(Curve 3) :- BottomWater- ConingorCresting- ChannelingthroughHighPermeability(Curve 4) :- FractureCommunicationbetweeninjectorandProducer
v Excesswaterproductionisaconcerninviewof:
ü ItiscausingwaterhandlingproblemsatFPFsü Watertreatmentanddisposalproblemsü RestrictingflowoflowP.Iintervals
ü OptimizingESPsinviewofchangeinP.Iü Severesandproductionwhichreflectonsandfillandhenceperforation
coveragev Stepstobetakentoarrestthisexcesswaterproductionproblem
ü Asproperdiagnosistoidentifythesourceofexcesswaterproduction:§ Properwellhistoryisakeyelement.§ Samelikethedoctorstartswithaskingthepatientabouthishealthhistory.
ü Aggressivewatershutofftobetakenuptoreducewatercutandincreaseoilproduction.
ExcessWaterProductionConcernsandChallenges
ReasonsandRouteCauseofhighwatercutProduction
ü AdverseMobilityratioinsuchfieldslikeBamboo,Heglig &Munga
ü Productionmechanism- ESP&PCPcausedHighdrawdown
ü Bottom&Edgewaterencroachment(MidField)
ü InjectionwaterbreakthroughinUnity(Talih WestField)
ü FlowbehindcasingduetopoorCementationinsomewells(BAM-X,NE-X&NE-Y)…
(Howcanwesolvethis?)
OverallWaterCutBehavior
Production Curve - Block 1,2
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
Jun-
99Se
p-99
Dec-
99M
ar-0
0Ju
n-00
Sep-
00De
c-00
Mar
-01
Jun-
01Se
p-01
Dec-
01M
ar-0
2Ju
n-02
Sep-
02De
c-02
Mar
-03
Jun-
03Se
p-03
Dec-
03M
ar-0
4Ju
n-04
Sep-
04De
c-04
Mar
-05
Jun-
05Se
p-05
Dec-
05M
ar-0
6Ju
n-06
Sep-
06De
c-06
Mar
-07
Jun-
07Se
p-07
Dec-
07M
ar-0
8Ju
n-08
Sep-
08De
c-08
Wat
er-C
ut (%
)
Heglig UN Toma-s EL nar Elharr Eltoor Bambo khairat Munga AvargeBack
Addnewtechniquetodetermineexcessivewaterproductionmechanismsasseeninpetroleumproductionwellshasbeendevelopedandverified.
log-logplotsofWOR(Water/OilRatio)vs.timeshowdifferentcharacteristictrendsfordifferentmechanisms.
ThetimederivativesofWORwasfoundtobecapableofdifferentiatingwhetherthewellisexpecting
•Waterconing,
•High-permeabilitylayerbreakthrough,
•Nearwellborechannelingand
•LayerConductivity
Fig 5-1 Coning (Numerical SimulationFig 5-2 High Permeability Layer (Numerical Simulation)Fig 5-3 Near Well Bore Flow
The vertical increase at the end (1800 days) is characteristic of a near well bore flow = this is “bad
water” and needs to be treated.
Fig 5-4 Layer Conductivity Good Water
This case WOR and WOR’ increase = layer conductivity = good water.WOR and WOR’ decrease at 3000 days because of an injector shut down in the near area. Note that they resume their increase on the same slopes sometime after when water comes from farther wells.Some sharp increase corresponds to near well bore flow followed by a remedial squeeze treatment
DiagnosisMethodsofExcessWaterProduction
In-Jun-99fromZarqa X(2176-2192.5mkb)
Drop in O/Liq due to Press
Start W-Injection IN Nov-01
Oil Dec wc inc-bad w
WELLPERFORMANCEANALYSISUN-X
WELLPERFORMANCEANALYSISUN-X
LayerConductivityFromWI-XtoUN-XinZCDistance(695m)
PROPOSALACTIONPLANforSEPRATELAYERINJECTIONUN-X
(CURRENT)UN--X
(PROPOSED CHNAGES)
2069 -2074 mkb
2186 - 2198 mkb
2267 - 2275 mkb
Zarqa-A
Zarqa - C
Zarqa - D
2069 -2074 mkb
2186 - 2198 mkb
2267 - 2275 mkb
Zarqa-A
Zarqa - C
Zarqa - D
PLTZone Relat Inj
Rate (%)Zarga A 12.75Zarga C 84.94Zarga D 2.31 Back
HighWaterCutDiagnosisMethods (Operation)
v ClassicMethods:
o SwabTest
ü SwabofMultilayerswillTakelongtimeofRig
ü Sometimesmisleading(itisalmostatstaticcondition)
v OtherMethods:
o RunPLT
ü GetReservoirparameters(pressure,BHP,PI)underdynamiccondition
ü PLTconductedEx:(He-X,TAS-X,Munga-X)
Heglig -XPLTResult
1) No contribution then single layer completion instead of commingling.
B-1AB-1BB-3AB-3B
B-1AB-1B
B-3BB-3A
GeneralWaterShutoftechniques
v ClassicMethods:
o CementSqueeze:
ü Openended tubingSTCEX:MG-X,Y
ü DrillableCementRetainer(DCR)
o WaterShutoffwithDrillableBridgePlug(DBP)EX:HE-X
v OtherTechniques:
ü MechanicalWaterShutoff
ü ChemicalWaterShutoff
ü PlantouseMultiPacker(onprogress)
ClassicWaterShutoffTechniques
vCementsqueezeandreperforate:
ØOpenendedtubingSTCandcementretainerDCR:o Successfully implemented atTY-Xon13August2008
o BentiuXlowerwaspermanently cementsqueezed
o BentiuXupperwascementsqueezedandpartiallyre-perforated
o Aradeibawassqueezedcementandtotallyre-perforated
• WellperformancePre/PostWSOjob:
Pre-WSO Post-WSOTY-X Well Schematic
Back
ClassicWaterShutoffTechniques
vWatershutoffusingDrillableBridgePlugDBPo Wassuccessfully beingutilizedatHE-XinJuly 2008o BentiulowerwasisolatedwithDBPsetat1731.0
mKB
ü Well performancePre/PostWSOjob:
HE-X Well SchematicPre-WSO Post-WSO
v LessonLearnto Betterdiagnosis&GoodreservoirevaluationwillLeadtohaveanexcellentresultinthere-completion
Back
MechanicalWatershutoffwasnotsuccessful
q Thetoolworksbyapplyingdifferentialhydrostaticpressureagainsttheswitches,whicharecalibratedtoopenandthencloseatcertainpressurevalues(24Mpa,18Mpaand12Mpa)
q LimitationofMechanicalWatershutoffTool:
o Thecandidateshouldbe7”casing(availabilityof7”packer).o No.ofproducingzones(three).o Differentialpressuretooperatetoolswitches(onandoff).o Surfacepressuremustnotexceed24.4MPa.(Wellheadpressurelimitation).o Welldepthshouldbemorethan2200mKB.o Sandproduction inducesprematureswitchesfailure.
q 1st TrialEH-X :v Failurecauseswereduetopackerleakageandswitchcheckvalvemalfunction.
q 2nd TrialEN-X:v Sandproduction causedtheswitchestostuckandledtoconfusioninproducingzones
combinationandhencetestresults.
MechanicalWSOEquipmentdiagram
EH-X1stTrialToolsDiagram
vLessonLearnt:
oSandpresenceaffectedthetoolswitchesoperation.oThetoolshouldmatchtheapplicationGNPOCwellsnotviseversa.oProvisionoffixableESPtoaccommodatedifferentreservoirscenariosfortestandproduction(i.e.formationpressureandPI).
Back
ChemicalWatershutoffTechnique
qThechemicalworksbyapplyingpluggingagent,highconductivityzonescanbeshutoffselectively.
qChemicalWSOchallengeso Chemicalshelflife.o NoorlittleimprovementinoilgainpoststheWSOjob.o Deepstudyshouldbecarriedouttoselectreliablechemicaltype.o Verylimitedcandidatemeetingtheoperationrequirements.o Operationandlogistic.o Effort&longtimeconsumedforpre-jobpreparationandpotablewatersupply.o Itsintensityandinitialgellingtimecanbeadjustedatacertainextentaccordingtothereservoircondition;temp.
o Wellusedtoproduce5712BLPD,407BOPDwith92%WCbeforejobexecution.Ø1st trialHE-X:
v Postjob thewellproduced200BOPDwith84%WCandthegrosswaslimitedtomax.1800 BLPDasperRErecommendation.
v Thewellcontinuedproduction atlowcontrolledrateforsixmonths.v sincenoimprovement inoilgainachieved,REadvisedtorevertbacktothepreviouscondition (currentlythegrossis5159,oil445and91%WC)
Ø2ndtrialHAM-X:vWellusedtoproduce2772BLPD,62BOPDwith98%WCbeforejobexecution.v Thewellwasabandonedafterclassicre-completion job.
EquipmentdiagramofChemicalWSO
Water tank 80M3
Water tank 80M3
Water tank40M3
Blending tank 8m3
Cement truck
Cementtruck Wellhea
d
Blending tank40m3
Blending tank 40m3
Blending tank 40m3
4〞Hose2-1/2〞Hose4〞Hoseconnected when need2-1/2〞Hose
Connected when need
2〞1502 hardpipeline
vLessonLearnt:oDeepstudyshouldbecarriedouttoselectreliablechemicaltype.oVerylimitedcandidatemeetingtheoperationrequirements.oItsintensityandinitialgellingtimecanbeadjustedatacertainextentaccordingtothereservoircondition;temp.
Back
ProductionPerformanceofHE-XAfter(WOJ)
02,0004,0006,0008,000
10,000
Jan-
08Fe
b-08
Mar
-08
Apr-0
8M
ay-0
8Ju
n-08
Jul-0
8Au
g-08
Sep-
08Oc
t-08
Nov-
08De
c-08
Jan-
09Fe
b-09
Mar
-09
Apr-0
9M
ay-0
9Ju
n-09
Avg WATER_RATE (bwpd) Avg WATER_RATE (bwpd)
Decrease in water production before and after WOJB -3A
B-1A
B -1B
1618 - 1624 mkb
1631 – 1638 mkb
1867 - 1872 mkb
HE-6
B -3B 1875 - 1878 mkb
DBP
0200400600800
1,0001,200
Avg OIL_RATE (bopd) Avg OIL_RATE (bopd)
Improvement in oil production Before and after WOJ
Production from Bentiu-X onlyProduction from Bentiu-X & ardeiba
MitigationPlantoDevelopBentiu-X&Bentiu-Y
Mitigation Plan to develop Bentiu-X & Bentiu-Y :Installation of dual ESP can revive production
from Bentiu-3 keeping upper layers un effected
Well PotentialUpper layers= 1035 bopd
Lower layer= 382 bopd
Total= 1473 bopd
Production Tubing
Power cablew/capillary tube
MB Packer
Upper zoneperforations
ESP
Packer
Casing
Lower zoneperforations
Single Production Tubing / Dual ESP System - Annular Flow
ESP
Back
Talih XPLTResult
• Ghazal-Xproduced2500bbl/dwater
üAsifwearewastingeffortof injectordaily
• NoContribution fromZargaatpresenceofGahzal,althoughTAS-Xdowndipwellproduced~250bopd
üCompletionStrategytoberevisedfornewwellsandforexistingwellsonopportunitybasis
PLTMunga-XResult
B-1AB-1B
B-1C
B-1BinterfereB-1A,
ü Actiontakenisreducingperforationintervalto2meter,decreasedthewaterproduction
ü B-1A
ü B-1B
ü Resultisverysuccessful,
ü sameideaconductedinMunga-Xwithverysuccessfulresult
Munga-X Performance after & Recompilation PLT JobClear water production reduced
MG-XPerformanceafterRecompbasedonPLTResultofMG-Y
Back
Strategyforwardinaddressingwaterproduction
Immediate
Medium Term
Ø ApplicationofY-ToolPLT.PermanentinstallationofY-Toolatkeywellsinablocktoreducecost.
Ø Completionstrategy:
ü singlelayercompletionforfuturewells.
ü ExploratorywellsPerforationintervalshouldbeadjusted&optimizedfarawayfromOWC
Ø ContinueDrillingofHorizontalwellstodelaywaterconing
Ø EstablishRMP,optimizeWaterProductionandenhanceRecoveryFactor.
Ø ApplicationofNewTechnology
ü MultipackerCompletion
ü ElectroTreatment
Ø ChemicalWaterShutOffü Indepthstudyandscreeningcriteriashouldbesetupfor
Mechanicalandchemicalwatershutoff
Long Term
MediumandLongTerm(IOR)
IOR
IORdrillinghorizontalwells:- reduceswaterconingduereducedrawdowninthe
reservoir.- Longlengthexposedtopayzoneincreaseproduction.- Moreeffectiveinthesandoilformationwithshort
distancetowater.- Horizontalwellsarenowcompletedwithnewmethods
inadditionaltotraditionalopenhole,casedhole,slottedlineorpre-perforatedpipe.
- Smartcompletioninvolvespermanentzonalsolutionwithexternalpackers,downholechoke&otherdeviceforcontrollingtheinflow.
IOR
WheredoweuseIORwaterinjection?• Waterinjectionwillnotimproverecoveryinareaof
strongwaterdrive.• Itispossiblewheredepletionisobservedandhas
edgewaterinflux.• Itislessexpensivetodrillwatersourcewellinto
shallowaquiferanddirectlytotheinjectorwithoutfurthertreatmentwhileproducedwaterneedstreatmentunit.
IOR(watermanagement)
• Diagnosetheentirewatercycle(reservoir,producers,facilities,injectors).
• Updatedthefielddevelopmentplan.• Identifyworkoveropportunities.• Applysuitabletechnology.
q Producers.q Injectors.q Surface.
MediumandLongTerm(EOR)
EOR Technology for Heavy Oil
Extra heavy oil
EOR
EOR
EOR
EOR
EOR
EOR
EOR
EOR
IOR
IOR
EOR
EOR
ConclusionsandRecommendations
v Declineinoilproductionisattributedmainlyduetohighwatercut,Watercutinmaturefieldsisonrisingtrendwhichhasseverenegativeimpacttofieldsreserve(EUR).
v Excesswaterproductionisheadacheforoperatingcompanyandwillcosttimeandmoneybettertoleaveinreservoir.
v Betterdiagnosis,understandingwillleadtosuccessfulremedialaction
v Diagnosticplotswhichwascarriedouttothatwell(UN-X)ProducedhighWCindicatesthishighwatercutmostlyrelatedtolayerConductivity.
v ControlliquidrateforNewwells&WOwells.