Fracturation hydraulique et stimulation .Fracturation hydraulique et stimulation hyyqdraulique FrancoisHenri

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  • Fracturationhydrauliqueetstimulationhydrauliquey q

    Francois HenriCornet,InstitutdePhysiqueduGlobedeStrasbourg

    Principedelafracturationhydraulique

    l h l Rleduchampdecontraintesurlagomtriedesgrandesfractureshydrauliques

    Stimulationhydraulique:lexempledeSoultz/sousForts

    Lequestionposeparlexploitationdes gazdeshistes

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  • Hydraulic fracturingHydraulicfracturing Thestressfieldclosetoacylindricalholeinanelastic

    fieldis:

    Iftheboreholeisparalleltoaprincipalstressdirection(Vertical) and a pressure is applied in the hole: ((Vertical)andapressureisappliedinthehole: =(H+h ) 2(H h )cos2 Pw,andruptureoccursfor:

    If th k h b l d d b d i l ti Both hydraulic fracturing and thermal cracking are mode Iftherockhasbeencooleddownbymudcirculation,thehoopstressis:=KT/E,whereKiscoefficientofthermalexpansion,EisYoungsmodulusandTisthedifferencebetweenfarfieldandboreholetemperature

    Correction for pore pressure effect (still debated)

    BothhydraulicfracturingandthermalcrackingaremodeIfractures

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    Correctionforporepressureeffect(stilldebated)

    2

  • Generating en echelon fractures in inclined wellsGeneratingenechelonfracturesininclinedwells

    ff t b h l f il effectsonboreholefailure

    Azimuthwhere

    Zoneswheremaximumstresscomponentreachits maximum value

    Pw

    +Pw

    minimumprincipalstressreachesitslowestvalue

    itsmaximumvalue

    TOHBOHTOH TOHBOHTOH

    BOIFB0IF BOIFB0IF

    Inclination of plane in

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    Inclinationofplaneinwhichshearstressiszero

    3

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  • Deinjectiondunagentdesoutnementpourlesvraies fractures hydrauliquesvraiesfractureshydrauliques

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  • Influencedelacontrainteprincipaleminimumsurlagomtriedesfractures

    Fracturation hydraulique = Extension spatiale des fracturesFracturationhydraulique=Rupturedetractionpure

    Extensionspatialedesfractureshydrauliquesenterrainhomogne

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  • Cas des terrains sdimentaires (bassin de Paris)Casdesterrainssdimentaires(bassindeParis)

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  • StimulationhydrauliquesurlesiteexprimentaldeSoultz/forts

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  • Objectif:induiredesmouvementsdecisaillementlelongdefractures prexistantes Rsultats du premier essai defracturesprexistantes.Rsultatsdupremieressaide

    stimulation (28503400m)(Sept.1993)

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  • Localisation des vnements microsismiquesLocalisationdesvnementsmicrosismiques

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  • Etudediffrentesprofondeursdelorientationdunuage

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  • Dterminationdelorientationdelacontraintemaximum horizontale partir des ovalisations demaximumhorizontalepartirdesovalisationsde

    forageetdesrupturesthermiques

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  • Caratrisationdesvariationsdorientationdunuagemicrosismiqueaveclaprofondeur

    Depth Mean Mean dip Number ofDepth interval (m)l

    Mean azimuth

    Mean dip Number of events

    2800 - 2900 N179E 87 329

    2900 3000 N165E 67 402

    3000 - 3200 N146E 86 416

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    1990 - 2200 N 147E 87

    15

  • Variationdeszonesdedinjectionenfonctiondelapressiondinjection

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  • LesitedeSoultzaujourdhui

    P t it ti f llPresentsituation:fourwellshavebeendrilled.

    Allthewellshavebeen Sedimentary coverStimulatedin1993at28503600m

    stimulatedbylargeprogressivehydraulicinjectionsatdifferentdepthsanddifferentperiodstoincrease their connectivity

    y

    crystallinebasement(granite)

    increasetheirconnectivity.

    Stimulatedin1995and1996at32003800m Stimulated in 2004 and

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    andin2000at44005000mStimulatedin2004and2005at44795000m

    Stimulatedin2003at44875100m

  • Time domains seismic tomographywith data sets adapted to the

    30 L/s 40 L/s 50 L/s

    with data sets adapted to theinjection parameters. (Calo et al., JGI,2011)We decided to apply the tomographic method to fourteen

    Data and subset selection

    not-equally populated sets to better fit the sub set separation with the hydraulic parameters of the injected fluids (injection rate and wellhead pressure).

    The whole period of the injection test has been

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    The whole period of the injection test has been divided into four main phases; 3 during the stimulation and 1 post-stimulation

  • Set1Set2Set3 Set4Set5Set6

    30ls1 40ls1

    Set7Set8Set9 Set10Set11Set12

    Seismicityrelocatedwiththe3D

    50ls1

    yvelocitymodels.Nointernalstructureobservedduringthestimulation(sets112).Butthepostinjectionseismicity(sets13and14)revealsoriented

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    p j y ( )structures

    Set13Set14 Caletal.,JGI,2011

  • Conclusionsurlinjectionforcej

    O t t t d l l lit d d l i di j ti Onnotequatretypesderponseselonlamplitudedelapressiondinjection:

    Rponselastiquedusystme;

    Circulationforcedansrseaudefracturesexistantavecdstabilisationlocaledanslesplansprexistantsquand =tg (n P)+C;etCangledefrottement et cohsion ( 0?) de la fracture prexistante concernefrottementetcohsion(=0?)delafractureprexistanteconcerne.

    Crationdunenouvellezonederuptureencisaillement( ) l d f d d =tg0 (n P)+C0;0 angledefrottementinternedumatriau;orientationde

    lanormaleauplanderupture(/4+0/2)deladirectiondemax;C0cohsiondelarochesaine;

    DveloppementdunefracturehydrauliquesiPinj minperpendiculairemin.

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  • Leproblmeposparlexploitationdes gazdeschistes

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