leak detection technologies：泄漏檢測技術

LeakDetectionPerformancePipelineSafetyTrustConferenceNovember17&18,2011NewOrleans,LouisianaWhyLeakDetection?

WhyLeakDetection?(Contd)MinimizethevolumeoflostfluidReduceriskoffire,explosionorothersafetyhazardsProtectthecompanyMinimizecleanupcostswithanearlyresponsetoaleakwarningProtectreputationDemonstrableacceptanceofresponsibilitybyexecutingaproactiveleakdetectionprogramAlwaysincreasingregulatoryinterestinpipelineintegrityprograms;includingleakdetectionNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference3HistoryManualpressure/flowreadingsandevaluationVoicecommunicationbetweenthefieldandanycenterofresponsibilitythatmayexist,orwithotherstationsalongthelineFamiliaritywiththepipelinebehaviorbycontrollersandtechnicianswascriticalRight-of-wayobservationincludingwalk-oversandfly-overswereamongfewleakdetectionoptionsNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference4AutomatedMeasurementsProprietaryloggingsystemsandSCADATransmitterandmetertechnologyAutomationtoolsandproductsthatacquireaccurateinformationabouthydraulicbehaviorToolstoassistinevaluatingtherelationshipsamongmeasurementsNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference5LeakDetectionPerformanceFromtheformerAPI1155(EvaluationMethodologyforSoftwareBasedLeakDetectionSystems):ThesystemcorrectlyindicatesthatthereisnoleakThesystemcorrectlyindicatesthatthereisaleakThesystemincorrectlyindicatesthatthereisaleak(falsealarm)Thesystemincorrectlyindicatesthatthereisnoleak(failuretodetect)DefinitionsabsorbedintoAPIRP-1130(ComputationalPipelineMonitoringforLiquidPipelines)November17&18,2011PipelineSafetyTrust2011PipelineSafetyConference6PerformanceMetricsSensitivity–CombinationofthesizeofadetectableleakandthetimerequiredtodetectitReliability–Ameasureofthesystem’sabilitytoaccuratelyassesswhetheraleakexistsornotAccuracy–Theabilityofasystemtoestimateleakparameterssuchasleakflowrate,totalvolumelost,andleaklocationRobustness–TheabilityofasystemtocontinuetofunctionduringunusualhydraulicconditionsorwhendataiscompromisedNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference7Meter-BasedLeakDetectionMostwidelyusedmethodonlonghaulpipelinesRequiresmetersatallentryandexitpointsAchievablesensitivitylimitedbymeteraccuracySomemethodscanbeimplementedinSCADA;orareoptionswithSCADAproductsSomeproductsarestand-aloneanddrivenbySCADAdataAlarmthresholdsmusttolerateandexpecttheimbalanceinmeterreadingsasthelinepacksandunpacksLeakevaluationalgorithmsthatcorrelateactualchangesinlinepackwithmeterimbalanceprovidethebestperformanceNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference8API1149PerformancePredictionsPredictsthetheoreticalbestperformancepossiblewithconfigureduncertaintiesNomarginforfalsealarmpreventionTemperatureuncertaintyandrelatedchangesindensityduringtransitislargestinfluenceonperformanceNotuncertaintyinmeasurement,butuncertaintyintemperatureprofilealongthelineOnetypeofleakdetectionsystemcanmoreaccuratelyestimatethetemperatureprofilethanothersystemsNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference9DefinitionsDryVolume–VolumeofthepipelineatatmosphericpressureandareferencetemperatureLinepack–TheincrementalquantityoffluidinthelineinadditiontothedryvolumeinfluencedbypressureandfluidtemperatureLinepackisheavilyinfluencedbytemperature’seffectonfluiddensityasispressure,butoftentoalesserdegreeProfile–ValueofaparameteroverthelengthofthepipelinesegmentNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference10Definitions(cont)Uncertainty–Potentialerrorinmeasurementsthatmustbeexpectedandaccountedfor;alsothedegreetowhichsomethingisunknownandmustbeestimatedorassumedbasedonsomewhatrelatedmeasurements.Real-TimeTransientModel(RTTM)–Accuratelytracksfluidtemperature/densityprofileswithconsiderationofpressureinordertoreduceuncertaintyinthelinepackNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference11MeterQualityvs.PerformanceNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference12Meter-BasedLeakBasicsFlow/Pressure/Temperaturemeasurementsonlyatsegmentend-pointsMeteredflowaccuracyimportantforhighsensitivityFluiddensity(molecules/massperunitvolume)variessignificantlywithtemperatureWarmfluidislessdense;ColdfluidismoredenseTemperature/densityprofileuncertaintyisthemostlimitingfactorinleakdetectionforsomepipelinesNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference13VolumetricFlowMeasurementBenefitsofvolumetric(notcorrectedfortemperatureandpressure)flowmeasurementBarrel-to-barrelassessmenttoleratesdifferencesindensityatinjectionanddeliverypointsToleratesswitchinginjectionsourcesofdifferenttemperaturesUsefulonshortlineswithsmallchangesintemperature/densityduringtransmissionNotusefulwheretemperature/densityprofilesaresignificantduetoheatlossNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference14NetbarrelFlowMeasurementBenefitsofnet(correctedfortemperatureandpressure)flowmeasurementUsefulforcustodytransferUndersteady-stateconditions,fluidinjectedatlowerdensitywillbalancewithdeliveredfluidathigherdensityInjectionsatslightlyhighervolumetricflowbalanceswithdeliveriesatlowervolumetricflowAssumesastabletemperature/densityprofileNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference15NetFlowMeasurementIssuesTransientconditionsthwartmanyalgorithmsinvolvingnetflowmeasurementsLinepackingandunpackingstillresultinanapparentnetflowimbalanceaswithbasicvolumebalancemethodsNetbarrelflowmeasurementsaggravatesimplebalancealgorithmswhereadifferenceindensityexistsatinjectionanddeliverypointsexceptundersteady-statestableconditionsNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference16NaturalFlowImbalanceDifferenceininjectedfluiddensityanddeliveredfluiddensityGradualchangeinfluiddensityduringtransitTemperature/densityprofilesarepoorlyunderstoodbymostsimplealgorithmsProfilechangesshapewithchangesinflowrateWatercrossingsandoccasionallywetsoilincreasethermalconductivityNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference17Meter-BasedLeakDetectionLimitationsAccountingforchangesordisturbancesinlinepackOperationalchangescausesthelinetopackorunpackasanormaloccurrenceShort-termhydraulicdisturbances(transients),includingchangesininjectiontemperatures,andtheireffectonlinepackmustbetoleratedorunderstoodinshort-termevaluationalgorithmsusedinrapidassessmentsOverextendedperiodsanyeffectsoftransientsarediluted;thusallowinggoodsensitivitybymostmeter-basedsolutionsoverlongobservationintervalsNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference18KeyConceptsPressuresandtemperaturesundersteady-stateconditionsprovidecurrentlinepackcharacteristicsDivergenceofmeterreadings(greaterimbalance)shouldbereflectedinlinepackchangesasseeninpressuresTransientsdisturbthisinformationandcanleadtosignificantshort-termlinepackuncertaintyOverlongtimeintervalsanyobservedvariationsinlinepackbecomeinsignificantcomparedtothequantityoffluidpassingthroughthepipelinesystemLong-termsensitivitysettingsdonotrequireasmuchtoleranceoflinepackuncertaintyasdoshorttermleakdetectionthresholdsNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference19LinepackEstimationFluiddensityassumedtobeanaverageofinjectionanddeliverydensityWeightedaverageCustomalgorithmsforcurvefittingRTTMthermalmodelstrackfluiddensityalongthelineChangeinflowratealtersthetemperature/densityprofileasanewquiescentstatedevelopsNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference20ProfilesTemperatureOccurswheninjectionanddeliverytemperaturesdifferSubjecttoheattransfercharacteristicsofenvironmentVarieswithflowrate/transittimePressureVariesasbatchedfluidsofdifferentcharacteristicstravelVariesasbatchesofdifferentdensitiestravelovermountainsProfilesareaccuratelytrackedbyReal-TimeTransientModels November17&18,2011PipelineSafetyTrust2011PipelineSafetyConference21Real-TimeTransientModel

Mostsophisticatedvolume/massbalancetoolIncludesathermalmodeltoincreasetheaccuracyoflinepackevaluation,thusallowingashorterdetectiontimeforadetectibleleakTracksheattransferalongthelineanddevelopsaccuratetemperature/densityprofilesasstepchangesinflowratesorinjectiontemperaturesoccurAllowsthermalmodeltuningtoachievethebestperformancebymodelingthehydraulicbehavioraccuratelyAutomatictuningcapabilitiesInstrumentsanitycheckingNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference22RTTMMythsSoftwareisexpensiveNotsignificantlymoreexpensiveSoftwarerequiresspecialskillsTrainingandfulltechnicalsupportisofferedbyvendorsKnowledgeofthepipelinephysicaldetailsisneededSoftwarerequiresongoingmaintenanceNotneeded,onceperformanceissatisfactory,butfurthertuningisoftenperformedtocontinuallyimproveperformanceRequiredifthepipelinenetworkischangedNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference23StaticPressureTestingExtremelyhighsensitivityZero(0)flowresultsinzero(0)uncertaintyinflowmeasurementWorkswellinarelativelyincompressibleliquidenvironmentRequirespressurecontrolequipmentNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference24StaticPressureTesting(contd)ShutinunderpressureatnearoperatingpressureMonitorpressuredecayforaperiodoftimeDroppressurebyhalfMonitorpressuredecayforaperiodoftimeAconsistentpressuredecayrateindicatesdecreasingdensityduetoheattransferAdifferentpressuredecayrateindicatesaleakwhoserateispressuredependentNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference25StaticPressureTestTrendsNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference26ConclusionSimplelinepackassessmentalgorithmshaveaplacewherelinepackisstableandlinepackvariationsanduncertaintydonotadverselyaffectleakassessmentRTTMtechnologysignificantlyreduceslinepackuncertaintyintransientenvironmentsandenablesleakdetectionapproachingthelimitsimposedbymeteraccuracyStaticpressuretestingisausefulintegrityverificationtoolMatchingthepropertooltothepipeline’soperationiscriticalNovember17&18,2011PipelineSafetyTrust2011PipelineSafetyConference27Training&ResponseAcriticalcomponentofanypipelineintegritymanagementprogramResponseprotocolshouldbeincludedintrainingandbeenforcedControllercanshutdowntheline