Wellhead - Wikipedia, The Free Encyclopedia

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24/2/2015 Wellhead Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Wellhead 1/3 Wellhead gas storage, Etzel Germany Wellhead From Wikipedia, the free encyclopedia A wellhead is the component at the surface of an oil or gas well that provides the structural and pressure containing interface for the drilling and production equipment. The primary purpose of a wellhead is to provide the suspension point and pressure seals for the casing strings that run from the bottom of the hole sections to the surface pressure control equipment. While drilling the oil well, surface pressure control is provided by a blowout preventer (BOP). If the pressure is not contained during drilling operations by the column of drilling fluid, casings, wellhead, and BOP, a well blowout could occur. Once the well has been drilled, it is completed to provide an interface with the reservoir rock and a tubular conduit for the well fluids. The surface pressure control is provided by a Christmas tree, which is installed on top of the wellhead, with isolation valves and choke equipment to control the flow of well fluids during production. Wellheads are typically welded onto the first string of casing, which has been cemented in place during drilling operations, to form an integral structure of the well. In exploration wells that are later abandoned, the wellhead may be recovered for refurbishment and reuse. Offshore, where a wellhead is located on the production platform it is called a surface wellhead, and if located beneath the water then it is referred to as a subsea wellhead or mudline wellhead. Contents 1 Components 2 Functions 3 Design specification 4 See also 5 External links Components The primary components of a wellhead system are: casing head casing spools

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Transcript of Wellhead - Wikipedia, The Free Encyclopedia

  • 24/2/2015 WellheadWikipedia,thefreeencyclopedia

    http://en.wikipedia.org/wiki/Wellhead 1/3

    Wellheadgasstorage,EtzelGermany

    WellheadFromWikipedia,thefreeencyclopedia

    Awellheadisthecomponentatthesurfaceofanoilorgaswellthatprovidesthestructuralandpressurecontaininginterfaceforthedrillingandproductionequipment.

    Theprimarypurposeofawellheadistoprovidethesuspensionpointandpressuresealsforthecasingstringsthatrunfromthebottomoftheholesectionstothesurfacepressurecontrolequipment.

    Whiledrillingtheoilwell,surfacepressurecontrolisprovidedbyablowoutpreventer(BOP).Ifthepressureisnotcontainedduringdrillingoperationsbythecolumnofdrillingfluid,casings,wellhead,andBOP,awellblowoutcouldoccur.

    Oncethewellhasbeendrilled,itiscompletedtoprovideaninterfacewiththereservoirrockandatubularconduitforthewellfluids.ThesurfacepressurecontrolisprovidedbyaChristmastree,whichisinstalledontopofthewellhead,withisolationvalvesandchokeequipmenttocontroltheflowofwellfluidsduringproduction.

    Wellheadsaretypicallyweldedontothefirststringofcasing,whichhasbeencementedinplaceduringdrillingoperations,toformanintegralstructureofthewell.Inexplorationwellsthatarelaterabandoned,thewellheadmayberecoveredforrefurbishmentandreuse.

    Offshore,whereawellheadislocatedontheproductionplatformitiscalledasurfacewellhead,andiflocatedbeneaththewaterthenitisreferredtoasasubseawellheadormudlinewellhead.

    Contents

    1Components2Functions3Designspecification4Seealso5Externallinks

    Components

    Theprimarycomponentsofawellheadsystemare:

    casingheadcasingspools

  • 24/2/2015 WellheadWikipedia,thefreeencyclopedia

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    casinghangerspackoffs(isolation)sealsbowlprotectors/wearbushingstestplugsmudlinesuspensionsystemstubingheadstubinghangerstubingheadadapters

    Functions

    Awellheadservesnumerousfunctions,someofwhichare:

    1. Provideameansofcasingsuspension.(Casingisthepermanentlyinstalledpipeusedtolinethewellholeforpressurecontainmentandcollapsepreventionduringthedrillingphase).

    2. Providesameansoftubingsuspension.(Tubingisremovablepipeinstalledinthewellthroughwhichwellfluidspass).

    3. Providesameansofpressuresealingandisolationbetweencasingatsurfacewhenmanycasingstringsareused.

    4. Providespressuremonitoringandpumpingaccesstoannulibetweenthedifferentcasing/tubingstrings.

    5. Providesameansofattachingablowoutpreventerduringdrilling.6. ProvidesameansofattachingaChristmastreeforproductionoperations.7. Providesareliablemeansofwellaccess.8. Providesameansofattachingawellpump,

    Designspecification

    Theoilindustryspecificationsforwellheadsystems(materials,dimensions,testproceduresandpressureratingsetc.)are:

    1. API6ASpecificationforWellheadandChristmasTreeEquipment2. ISO10423WellheadandChristmasTreeEquipment

    Ingeneralwellheadsarefivenominalratingsofwellheads:2,3,5,10and15(x1000)psiworkingpressure.Theyhaveanoperatingtemperaturerangeof50to+250degreesFahrenheit.Theyareusedinconjunctionwithringtypesealgaskets.

    Ingeneraltheyieldstrengthofthematerialsrangefrom36000to75000psi.

  • 24/2/2015 WellheadWikipedia,thefreeencyclopedia

    http://en.wikipedia.org/wiki/Wellhead 3/3

    WikimediaCommonshasmediarelatedtoWellheads.

    Seealso

    PutealWaterwellheadPumpjackAmericanPetroleumInstituteDrillingrig(petroleum)Christmastree(oilwell)

    Externallinks

    SchlumbergerOilfieldGlossary:wellhead(http://www.glossary.oilfield.slb.com/Display.cfm?Term=wellhead)

    Retrievedfrom"http://en.wikipedia.org/w/index.php?title=Wellhead&oldid=606468562"

    Categories: Oilwells Oilplatforms Petroleumproduction Oilfieldterminology

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