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Infinity: EngineeringDivision: FieldDevelopmentClient: ConfidentialE&PProject: FlowAssuranceOptimisation
BackgroundThe client had experienced a range ofslugging predictions from the reservoir andcompletionsanalysishadbeenperformed inGAPProspersoftware.Infinitywereengagedto verify the results using a three-phasesimulator including a holistic analysis to thesystem.Recommendationsontheassociatedslugging mitigation and management weremade. This was done through modellingchanges in subsea line size and consideringoperationalalternatives.
ChallengeThe client has previously performed aProsperanalysisonsomedrillingalternativesbut,asProspermodelsonlyrunsteadystate,this would not show the impact duringoperations. As such, Infinity undertook amore comprehensive study using themultiphasehydrodynamicsimulatorOLGAtoinvestigate the behaviour of the fluid undertransient conditions. From a flow assurancestability perspective, smaller tubing couldpotentially reduce the pressure fluctuationscurrently observed at thewell tubing in thewells. These fluctuations would typically betranslated into slugging issues at theseparatorthatcouldresult in largesurgesofliquidtypicallyresponsibleforhigh-leveltripsatthetopsidesseparators.
SolutionIn later life ofwell, orwhen thewellswereoperatingwith lower gas lift injection rates,at water cuts above 50% there weresignificant advantages with the single stringarrangement. These included reducingpressure fluctuations at the tubing andsluggingpotential.
Anoverallproductionlossbetween25%and39%wasidentifiedforthecasesusingoneofthe single string completions for early andmid-life of well. After discussions with theclient this option was not identified as adisadvantage.Thiswasduetothecompletelydifferent business models adjacent to eachcase.Itwouldrepresentadeferraleconomicexercisethatwouldhavetobeanalysedinabroadspectrumofscenarios.Theseinclude:• possible flowstabilityadvantagesof the
smallertubinganditsimpactontopsidesfacilitiesuptime
• productionreliability• reduced gas lift injection requirements
translated into increase gas exportvalues
• cost savings directly related to thedrillingoperationsetc
Thestudyiscurrentlybeingusedtoreviewtheclient’sapproachtofielddevelopmentandshort-termdrillingplans.Itisalsobeingexpandedtoprovideproductionoptimisationstrategiestocurrentlyproducingwells.
