IWCF井控培训课程之formationpressure地层压力

IWCF井控培训课程之formationpressure地层压力第一页，共26页。Thetwopressuresofprimaryconcernare:Formationpressure&Hydrostaticpressure.Formationpressure:istheforceexertedbyfluidsintheformation.-

Alsocalledreservoirpressure,&/or-Shut-inbottomholepressure.第二页，共26页。

TheoriginofF.P.:Itrelatestohowsedimentarybasinsareformed.Aslayeruponlayerofsedimentsaredeposited,overburdenpressureonthelayersincreases,&compactionoccurs.Soanyfluidsintheformationaresqueezedintopermeablelayers,suchassandstone.Ifthepermeablelayeriscontinuoustothesurface(outcropsonthesurface)pressurehigherthannormalcannotform.Butifthefluidistrappedbecauseofsomeanomaly,pressurehigherthannormalcanform.

第三页，共26页。NormalpressureSubnormalpressure-Abnormalpressure第四页，共26页。

Thetermisderivedfrom“hydro”,meaningwaterorliquid,&“static”,meaningatrest.Hydrostaticpressurereferstothepressureofdrillingfluidinthewellbore.第五页，共26页。

Inthewellbore,H.P.istheresultofthefluiddensity&trueverticaldepthofthefluidcolumn.第六页，共26页。Where:C=0.052,ifmuddensityisexpressedintermsofppg,&C=0.00695,ifmuddensityisexpressedintermsofpcf.第七页，共26页。

Pressure&mud

gradientistheamountpressurechangeswithdepth.Itisobtainedbymultiplyingthemudweightbytheconstant.MG=MW×C0.0520.00695第八页，共26页。PressureormudgradientisobtainedbymultiplyingmudweightbytheconstantC.So,thegradientfora12ppgmudis:MG=12×0.052=0.624psi/ft第九页，共26页。EX.Thehydrostaticpressureofamudwith0.624psi/ftgradientina11,325ftwellwouldbe,HP=0.624×11,325HP=7067psi第十页，共26页。Normalpressuregradientscorrespondtothehydrostaticgradientofafreshwaterwithadensityof8.33ppg(0.433psi/ft)to9.0ppgsalinewater(0.465psi/ft)column.第十一页，共26页。第十二页，共26页。GRADIENTPSI/FTFormationPorePres.MudPres.Frac.P.Aghajari0.4330.4500.68Mishan0.4650.4790.70Gs.(7)0.4650.500.78Gs.(6-1)0.8-1.00.85-1.101.1Asmari0.24-0.490.433-0.560.74Pabdeh0.5-0.540.52-0.560.81Gurpi0.5-0.540.52-0.560.83Ilam0.540.560.74Sarvak0.540.560.74Fahliyan0.540.560.79第十三页，共26页。Ex.Drawthelinesofpressuregradients(pore,mud&fracture)forAj.toAs.formationsbasedontableofdatainpreviousslide.Correlateitwithlithology&stratigraphiccolumn.

第十四页，共26页。FracturepressureAreaofLostCirculation0.5ppgSafetymarginPorepressureKickareaBHPlessthanformationpressurecausesthewelltoKick,&greaterthanfracturepressurecauseslostreturn.

第十五页，共26页。Normalpressuregradient:about0.433-0.465psi/ft.Thegradientslessthan0.433psi/ft&greaterthan0.465psi/ftareknownassubnormal&abnormal,respectively.

第十六页，共26页。Pressure,psiDepth,ftSurfacePressuregradient=0.433psi/ftPressuregradient=0.465psi/ftSubnormalAbnormal第十七页，共26页。Annularpressure,thepumppressurerequiredtomovemuduptheannulus,mustbeconsideredinwellcontroloperations.Thispressureislessthan200psiatthereducedpumpspeedsusedinkillingawell.第十八页，共26页。

Whenmudisbeingcirculated,bottomholepressureequalshydrostaticpressureplusthepressurerequiredtomovemuduptheannulus.Annularpressurelossexistsonlywhenmudisbeingcirculated&itceaseswhenthepumpisstopped.第十九页，共26页。H.Khedersolh20第二十页，共26页。

TheamountofAPLdependsonwhetherthemudflowintheannulusislaminarorturbulent.第二十一页，共26页。APLishigherwhenthemudisinlaminarflow.Flowintheannulusisusuallylaminar,becausethemudvelocityintheannulusduringwellcontroloperationsisdecreasedbyloweringthepumpspeedbelowthespeedusedfornormaldrillingoperations.

第二十二页，共26页。

APLinlaminarflow:第二十三页，共26页。Ex.CalculateAPLaccordingtodata’savailableL=16,000ft(TVD),YP=8lb/100ft2,PV=24cpV=1.2ft/sec,Dh=8.5in.,Dp=4.5in.APL=(16,000×8)/225(8.5-4.5)+(16,000×

24×

1.2)/1,500(8.5-4.5)2=(128,000/900)+(460,800/24,000)=142.2+19.2=161.4psi第二十四页，共26页。

AnotherwaytolookattheBHPinc