空中检测输气管道泄漏的评价英文.docx

空中检测输气管道泄漏的评价英文.docx

《空中检测输气管道泄漏的评价英文.docx》由会员分享，可在线阅读，更多相关《空中检测输气管道泄漏的评价英文.docx（12页珍藏版）》请在冰豆网上搜索。

空中检测输气管道泄漏的评价英文

SPE57461

TheEvaluationofAerialSurveysforDetectionofNaturalGasPipelineLeaksK.Aminian,SPE,A.Chamorro,SPE,S.Ameri,SPE,andH.I.Bilgesu,SPE,WestVirginiaUniversity

Copyright1999,SocietyofPetroleumEngineersInc.

Thispaperwaspreparedforpresentationatthe1999SPEEasternRegionalMeetingheldinCharleston,WestVirginia,21–22October1999.

ThispaperwasselectedforpresentationbyanSPEProgramCommitteefollowingreviewofinformationcontainedinanabstractsubmittedbytheauthor（s.Contentsofthepaper,aspresented,havenotbeenreviewedbytheSocietyofPetroleumEngineersandaresubjecttocorrectionbytheauthor（s.Thematerial,aspresented,doesnotnecessarilyreflectanypositionoftheSocietyofPetroleumEngineers,itsofficers,ormembers.PaperspresentedatSPEmeetingsaresubjecttopublicationreviewbyEditorialCommitteesoftheSocietyofPetroleumEngineers.Electronicreproduction,distribution,orstorageofanypartofthispaperforcommercialpurposeswithoutthewrittenconsentoftheSocietyofPetroleumEngineersisprohibited.Permissiontoreproduceinprintisrestrictedtoanabstractofnotmorethan300words;illustrationsmaynotbecopied.Theabstractmustcontainconspicuousacknowledgmentofwhereandbywhomthepaperwaspresented.WriteLibrarian,SPE,P.O.Box833836,Richardson,TX75083-3836,U.S.A.,fax01-972-952-9435.

Abstract

Pipelineleaksareofmajorconcerntonaturalgasindustry.Theycanresultinlossofrevenue,potentialdangertopublic,andenvironmentaldamage.Toensurepipelinesafetyandreliability,agroundsurveillanceprogramtodetectleaksisconductedonannualbasis.Consideringthenumberofmilesofnaturalgaspipeline,thismethodistimeconsumingandexpensive.Therehasbeeninterestindevelopingothermethodsforrapidsurveyofnaturalgaspipelines.Thevisualaerialsurveys,whichrelyontheidentificationofdeadvegetationtodetectaleaksource,haveaverylimitedapplication.Theuseofinfraredtechnologytodetectaleakbasedonthermaldifferencesbetweentheleakedpipelinegasandsurroundingareahasnotbeendevelopedtothepointtobereliable.Aneffectiveaerialpipelineleakdetectionsystemhasbeendevelopedrecently.Thesystemutilizesanaircraft,whichisequippedwithflameionizationhydrocarbondetector.Thehydrocarbondetectorcananalyzethesamplestakenduringtheflightoverthepipelineright-of-way.Presenceofnaturalgasanomalies,thatarelargerthannaturalgasbackgroundlevels,representapotentialleaksource.Theaccuracyandreliabilityoftheaerialsurveyshoweverremainsquestionable.Thispaperreportstheresultsofthebothmodelingstudiesandfieldtestsconductedtoevaluatetheaccuracyandreliabilityoftheaerialsurveys.

Buoyantplumeriseanddispersionhasbeenstudiedexten-sivelybecauseitistheprimarymechanismfordispersingstackgasestotheenvironment.Ajetplumemodelthatpredictsthetrajectoryanddilutionofverticallyorientedgasjetwasconsid-eredforthisstudy.Themodelwasthenmodifiedtodevelopuser-friendly（Windows-basedinputandoutputinterfaces.Theplumerisemodelwasthenutilizedforsensitivityanalysisinordertodesignafieldtest.Themodelingresultswereutilizedtodeterminetheoptimumflightplan.Apipelineleakwassimulatedbyreleaseofthenaturalgasduringthefieldtest.Themodelpredictionswerecomparedtothemeasuredgasconcentrationtoevaluatethepredictabilityofthemodel.Themeasuredgasconcentrationsweregenerallyfoundtobeinagreementwiththepredictedvalues.Theresultsindicatedthatmodelcanbeusedforthedesignoftheflightplanandtheanalysisofthefielddata.Introduction

Thepossibilityofnaturalgasleaksfromthepipelines,consider-ingthenumberofmilesofnaturalgaspipeline,isacertainty.Aneffectivestrategyforensuringpipelinereliabilityandsafetyistodetecttheleaksintheearlystagesbeforetheyresultinmassiveruptures.Annualgroundpipelinesurveillanceprogramisthemainmethodofpipelineinspectiontodetectleaks.However,thismethodistimeconsumingandexpensive.Therehasbeenasignificantinterestinnaturalgasindustryfordevelopingarapidsurveyofgaspipelines.Thevisualaerialsurveysinvolvevisualsurveillancebypilotsastheyflyoverthepipelineright-of-way.Theseconventionalsurveysrelyontheidentificationofdeadvegetationtodetectaleaksource.Theapplicationofthistechniqueisratherlimitedtosummerseasonandareasthatarecoveredwithsufficientgreenvegetation.Theinfraredtechnologyhasbeenalsoconsideredforpipelineleakdetection.Thistechnologyutilizesthermaldifferencesbetweentheleakedpipelinegasandthesurroundingstodetectaleak.Itishoweverdifficulttoapplythistechnologywheretheclimateiscoldorwherethereissignificantvegetationcanopy.

Anewairbornesystem1equippedwithflameionizationdetectorhasbeendevelopedtodetectthegasplumegeneratedbyapipelineleak.Thepotentialsavingsintimeandcostprovidedbythistechnologyissignificant.Atwinengineaircraftisthepreferredforaerialmonitoring.Ahelicopterhowevercouldbeusedwhentheterrainisdifficultforafixedwingaircrafttohandle.Theheartofsystemisahydrocarbonanalyzer,whichutilizesaflameionizationdetector（FIDtoanalyzethesamplesextractedfromtheundisturbedairbeyondtheaircraftnose.GasAnalysisresultsareacquiredbythedataacquisitionsystemaboardtheaircraft,andaredigitallystoredforsubsequentreproductionandanalysis.Geographicalcoordinatesarealsorecordedateachsamplingpointalongtheflightpathusingdatafromtheon-boardgeographicalpositioningsystem（GPS.Thedigitalinformationalongwiththeinformationfromthevideocamera,isdisplayedonthevideomonitor.Inthismanner,theon

2SPE57461

K.AMINIAN,A.CHAMORRO,S.AMERI,H.I.BILGESU

boardoperatorhastheabilitytoimmediatelyalertthegroundpersonnelifamajorleakislocated.Thisisespeciallyimportantinemergencyresponsesituationswhererapididentificationofaleaksourceisnecessary.Thevideomonitorallowsthesystemoperatortoidentifyanyobvioushydrocarbonsourcessuchasfarmingfeedlots,compressorstations,etc.Variablesliketemperature,windspeed,andprecipitationarecriticaltoconductasatisfactorysurvey.Ingeneralthepreferredweatherconditionswouldbetemperaturesabovefreezing,windspeedslessthan10knotsandnoprecipitation.Undertheseconditionstheplumecausedbyapipelineleakhastheopportunitytobecomewellestablishedandthesourceofapipelineleakcanbelocatedusingthedataobtainedfromthesurvey.

Todetectagasanomaly,theaircraftmustflythroughagasleakplumewithaconcentrationabovethemethanebackgroundlevelandlongenoughforFIDtorespond.TheresponsetimeforFIDisabout5secondstoreach85percentofthemaximumsignalstrength.Theaircraftatflightaltitudemaynotbeintheplumelongenoughtoachieve100percentinstrumentresponsetotheelevatedhydrocarbonlevels.Itshouldbenotedthatashortsamplingdurationcanalsodetectthepresenceofnaturalgasbutthesignalstrengthwillbereduced.However,theexactconcen-trationofthegasisnotofcriticalconcernanditisonlynecessarytoqualitativelyidentifyalargerthanbackgroundhydrocarbonanomalytodeterminethepresenceofapotentialleaksource.Theaerialpipelineleakdetectionsystem,likeanyothergasdetectionmethod,hasitslimitationthatmustbeconsidered.Thekeycriticalissuesincludethedifficultyinpredictingthelocationandsizeofthegasplumeanddilutionofthemethaneplumebelowthedetectablelevelatflightaltitudeduetodispersion.Theseproblemscouldcausetheflyovertesttoeasilymisstheplume.Todealwiththeseproblems,theatmosphericdispersionoftheleakedmethaneplumeundercertainmeteorologicalconditionsneedstobeinvestigated.Boththeoreticalandexperimentalapproacheswereundertakeninthisstudytoinvestigatetheinfluenceofatmosphericconditionsonmethanedispersionandconsequentlyonleaksdetectionatflightaltitudes.Background

Buoyantplumeriseanddispersionhasbeenstudiedextensivelybecauseitistheprimarymechanismfordispersingstackgasestoenvironment.Theplumerisemodelsaredevelopedbasedonthefundamentallawsoffluidmechanics.Thebackgroundmaterialsonearlyplumerisemodelshasbeenextensivelyreviewedintheliterature.2Morerecently,asophisticatedcomputerdispersionmodel3knownasDEGADIS（DEnseGAsDISpersionhasbeendeveloped.ThemodelhasbeenvalidatedagainstanumberofwindtunnelandfieldtestdatainvolvingLNG,propane,freon,ammonia,nitrogentetroxideandhydrogenfluoridereleasesonflatlevelterrain.DEGADISwasoriginallydevelopedtomodelthedispersionofheavierthanairflammableandtoxicvaporclouds.Ajetplumesourcemodel4waslaterinterfacedwithDEGADIStoprovideforthepredictionofthetrajectoryanddilutionofverticallyorientedgasjetswithpositiveornegativebuoyancy.Thejetwasassumedtobedischargedfromacircularventwithuniformvelocityprofile.Primarysources,whicharenotcircular,canbenormallymodeledascirclewiththesamearea.Therefore,DEGADIScanbeusedformodelingnaturalgasatmosphericdispersionalthoughithasnotbeenvalidatedformethane.

Itisimportanttodiscusssomeoftheimportantmeteorologicalfactorssincetheylargelycontroltheatmosphericdispersion.Windspeed,winddirection,andatmosphericstabilityareimportantfactorsinevaluatingdiffusionfromanysource.Winddilutesthegasbyprovidingseparationbetweenth