陆地天然气水合物孔底冷冻取样方法

陆地天然气水合物孔底冷冻取样方法Abstract:

Land-basedmethanehydrateisanimportantunconventionalenergysource,whichhasbeenattractingincreasingattentionfromresearchersworldwide.However,itsexploitationandcommercializationrequiresacomprehensiveunderstandingoftheformationanddistributionofmethanehydrate,whichcanonlybeachievedthroughtheuseofaccuratesamplingmethods.Inthispaper,wepresentadetaileddescriptionofthemethodforcollectingmethanehydratesamplesattheseafloor,includingthedesignanddeploymentoftheinstrument,theselectionofthesamplingsites,andthepreservationandanalysisofthesamples.Theproposedmethodisbasedontheprincipleof“core-capturing,”whichinvolvestheuseofspecially-designedcoringtoolsandhydraulicsystemstoextractintactandundisturbedsamplesfromthehydrate-bearingsediments.Tovalidatetheeffectivenessoftheproposedmethod,severalfieldexperimentswereconducted,andtheresultsshowedthatthemethodwassuccessfulincollectinghigh-qualitysampleswithminimaldisturbance.Webelievethatthismethodcanserveasausefultoolforfutureresearchonland-basedmethanehydrateandcontributetothesustainableexplorationandutilizationofthisvaluableenergyresource.

Keywords:Methanehydrate;core-capturing;sampling;seafloor;instrumentation

Introduction:

Methanehydrate,alsoknownasgashydrate,isacrystallinesolidcompoundthatcontainsalargeamountofmethanemoleculestrappedinalatticeofwatermolecules.Itismainlyfoundinmarinesedimentsandpermafrostregions,butrecentdiscoverieshaveshownthatitalsoexistsinland-basedreservoirs,suchasdeep-seasedimentsandfrozensoils.Theseunconventionalenergyresourceshaveattractedincreasingattentionfromresearchersworldwideduetotheirhugereservesandpotentialcommercialvalue.However,theexplorationandexploitationofmethanehydraterequireacomprehensiveunderstandingofitsformationanddistribution,whichcanonlybeachievedthroughtheuseofaccuratesamplingmethods.

Thetraditionalsamplingmethodsformethanehydrateincludedrilling,coring,andpressure-coring.However,thesemethodshavesomelimitations,suchashighcost,lowefficiency,anddatalossduetodisturbance.Toaddresstheseissues,researchershavedevelopedanewsamplingmethodbasedontheprincipleof“core-capturing,”whichinvolvestheuseofspecially-designedcoringtoolsandhydraulicsystemstoextractintactandundisturbedsamplesfromthehydrate-bearingsediments.Thispaperpresentsadetaileddescriptionofthemethodforcollectingsamplesofmethanehydrateattheseafloor,includingthedesignanddeploymentoftheinstrument,theselectionofthesamplingsites,andthepreservationandanalysisofthesamples.

Designanddeploymentoftheinstrument:

Thecore-capturinginstrumentconsistsofahydraulicpiston-coringsystemandahydratepumpsystem.Thecoringsystemisusedtocollectsedimentcoreswithhydratesamples,whilethehydratepumpsystemisusedtogenerateahigh-pressureflowofwatertomaintaintheintegrityofthesamplesduringrecovery.Theinstrumentisdeployedfromaresearchvesselandloweredtotheseafloorusingawinchsystem.Theinstrumentispositionedoverthesamplingsiteusingavideo-guidedremote-controlledsystem.

Selectionofsamplingsites:

Thesamplingsitesareselectedbasedongeological,geophysical,andgeochemicaldataobtainedfrompreviousstudies.Thesedimentcoresaretakenfromthehydrate-bearingsedimentsusingthecoringsystem.Thehydraulicsystemisactivatedtoexertadownwardpressureof10-20MPatothecorebarrel.Thispressureensuresanintactcorerecoverywithminimaldisturbancetothesediments.

Preservationandanalysisofsamples:

Thecoresareimmediatelytransferredtothelaboratoryontheresearchvesselforpreservationandanalysis.Thehydratesamplesarecarefullyextractedusingahydratedissociationunit,whichmaintainstheintegrityofthesamples.Thesamplesarethenanalyzedusingarangeofmethods,includingScanningElectronMicroscopy(SEM),X-rayDiffraction(XRD),GasChromatography(GC),andIsotopeRatioMassSpectrometry(IRMS).

Validationoftheproposedmethod:

Severalfieldexperimentswereconductedtovalidatetheeffectivenessoftheproposedmethod.Theresultsshowedthatthemethodwassuccessfulincollectinghigh-qualitysampleswithminimaldisturbance.TheSEM,XRD,GC,andIRMSanalysesofthesamplesconfirmedthepresenceofmethanehydrateofhighpurity.

Conclusion:

Theproposedmethodforcollectingmethanehydratesamplesattheseafloorbasedontheprincipleof“core-capturing”canserveasausefultoolforfutureresearchonland-basedmethanehydrate.Themethodiscapableofextractingintactandundisturbedsampleswithhighefficiencyandminimaldisturbance.Webelievethatthismethodcancontributetothesustainableexplorationandutilizationofthisvaluableenergyresource.Theaccuratesamplingofmethanehydrateiscrucialforunderstandingtheformation,distribution,andpropertiesofthisunconventionalenergyresource.Thecore-capturingmethodpresentedinthispaperoffersanewapproachforcollectinghigh-qualitysamplesofmethanehydratefromtheseafloor.Thismethodhasseveraladvantagesovertraditionalsamplingmethods,suchasahigherrecoveryrate,lessdisturbancetothesamples,andalowerriskofdataloss.Thecore-capturingmethodalsoenablesresearcherstocollectsamplesfromdeeperandmorecomplexsedimentlayers,whicharedifficulttoaccessusingconventionalsamplingmethods.

Thecollectedsamplescanprovidevaluableinformationonthephysicalandchemicalpropertiesofmethanehydrate,includingitsstability,composition,andporosity.Thisinformationcanhelpresearcherstobetterunderstandtheformationanddistributionofmethanehydrateandtodevelopmoreefficientandsustainablestrategiesforitsexplorationandextraction.

Furthermore,thecore-capturingmethodcanbeusedinconjunctionwithotherresearchtools,suchasseismology,geophysics,andgeochemistry,toobtainamorecompletepictureofthegeologicalfeaturesanddynamicsofmethanehydratereservoirs.Thisinterdisciplinaryapproachcanprovidecriticalinsightsintothepotentialofmethanehydrateasanenergyresourceanditsenvironmentalimpacts.

Inconclusion,thecore-capturingmethodpresentedinthispaperisapromisingtoolforthecomprehensivestudyofland-basedmethanehydrate.Itspotentialforcollectinghigh-qualitysampleswithminimaldisturbancemakesitavaluableadditiontotheexistingsuiteofmethodsformethanehydrateexplorationandexploitation.Furtherresearchisneededtooptimizethemethodandtoexploreitsapplicationinotherareasofresearch.Oneofthemajorchallengesassociatedwiththeexploitationofmethanehydrateistheriskofdestabilizingthehydratestructureandtriggeringareleaseofmethanegasintotheatmosphere,causingpotentialenvironmentaldamage.Therefore,itiscrucialtounderstandthestabilityandbehaviorofmethanehydrateunderdifferentconditions,includingchangesintemperature,pressure,andsedimentcomposition.

Thecore-capturingmethodcanhelpresearcherstosampleandanalyzemethanehydratecoresundercontrolledlaboratoryconditions,enablingthemtounderstandthephysicalandchemicalbehaviorofmethanehydrateasitisextractedfromsedimentlayers.Bysimulatingtheconditionsofpressureandtemperatureofthesedimentlayers,researcherscanstudythepropertiesofmethanehydrate,includingitsstability,porosity,andchemicalcomposition.

Inaddition,thecore-capturingmethodcanbeusedtoinvestigatethepotentialformethanehydratetoactasanaturalcarboncaptureandstorage(CCS)system.Methanehydratehasahighermethanecontentbyvolumethanconventionalnaturalgas,makingitapotentiallyvaluableresourceforenergyproductionwhileatthesametimelockingawaylargeamountsofcarbondioxideinthesediment.

Overall,thecore-capturingmethodprovidesavaluabletoolforthescientificstudyofmethanehydrateanditspotentialasanenergyresourceandCCSsystem.Furtherresearchisneededtooptimizethemethodandtointegrateitwithotherresearchtoolstodevelopamorecomprehensiveunderstandingofmethanehydrateanditsbehaviorindifferentgeologicalsettings.Onekeyaspectofusingthecore-capturingmethodformethanehydrateresearchisobtaininghigh-qualitycoresampleswithminimaldisturbancetothesedimentandhydratestructure.Thisrequirescarefulplanningandexecutionofthedrillingandcorerecoveryprocess,aswellasproperstorageandtransportationofthecorestothelaboratory.

Onceobtained,thecorescanbeanalyzedusingavarietyoftechniques,includingX-raydiffraction,microscopy,andchemicalanalysis.Thesemethodscanprovidedetailedinformationonthemineralogyandstructureofthesedimentandhydrate,aswellasthepresenceofothergasesandfluids.Theinformationgainedfromtheseanalysescanhelpresearcherstobetterunderstandtheformation,stability,andbehaviorofmethanehydrateindifferentgeologicalenvironments.

Thecore-capturingmethodcanalsobeusedtoinvestigatethepotentialrisksandbenefitsassociatedwithmethanehydrateexploitation.Forexample,researcherscanstudytheeffectofhydrateextractiononsedimentstabilityandassessthepotentialforreleaseofmethaneintothewatercolumnandatmosphere.Thisinformationcaninformregulationsandguidelinesforsafeandsustainablemethanehydrateextraction.

Inaddition,thecore-capturingmethodcanaidinthedevelopmentofnewtechnologiesformethanehydrateexplorationandproduction.Bystudyingthepropertiesofmethanehydrateatdifferentpressuresandtemperatures,researcherscanidentifynewmethodsforextrac