Reservoirengineeringformulas andcalculations
ChapterOutline
1.1APIgravity
1.6Averagetemperatureofagascolumn
1.7Calculationoffractionalflowcurve
1.18Cumulativeeffectivecompressibility—Fetkovich 10
1.19Cumulativegasproduction—Tarner’smethod 10
1.20Cumulativeoilproduction—Undersaturatedoil reservoirs 11
1.21Deliverabilityequationforshallowgasreservoirs 11
1.22Dimensionlesspressure—KamalandBrigham 11
1.23Dimensionlessradiusofradialflow—Constant-rate production 12
1.24Dimensionlesstime—MyhillandStegemeier’smethod 12
1.25Dimensionlesstimeforinterferencetestingin homogeneousreservoirs—Earlougher 13
1.26Dimensionlessverticalwellcriticalrate correlations—Hoyland,Papatzacos, andSkjaeveland 13
1.27Dimensionlesswellborestoragecoefficientof radialflow—Constant-rateproduction 13
1.28Effectivecompressibilityinundersaturatedoil reservoirs—Hawkins 14
1.29Effectivewellboreradiusofahorizontal well—Method1—Anisotropicreservoirs 14
1.30Effectivewellboreradiusofahorizontal well—Method1—Isotropicreservoirs 15
1.31Effectivewellboreradiusofahorizontalwell—van derVlisetal.method 16
1.32Effectivewellboreradiusofawellinpresenceof uniform-fluxfractures 16
1.33Effectivewellboreradiustocalculateslantwell productivity—vanderVlisetal. 16
1.34Estimationofaveragereservoirpressure—MDH method 17
1.35Formationtemperatureforagivengradient 17 1.36Fractionofthetotalsolutiongasretainedinthe reservoirasfreegas 17
1.37Fractionalgasrecoverybelowthecritical desorptionpressureincoalbedmethanereservoirs 18 1.38Freegasinplace 18
1.39Gasadsorbedincoalbedmethanereservoirs 19 1.40Gasbubbleradius 19 1.41Gascapratio 19 1.42Gascapshrinkage 20 1.43Gasdriveindexingasreservoirs 20 1.44 Gasexpansionfactor 20 1.45Gasexpansiontermingasreservoirs 21 1.46Gasflowrateintothewellbore 21 1.47Gasflowunderlaminarviscousconditions 22 1.48Gasformationvolumefactor 22 1.49Gashydratedissociationpressure 22 1.50Gasmaterialbalanceequation 23 1.51Gasproducedbygasexpansion 23 1.52Gassaturation—Water-drivegasreservoirs 24 1.53Gassolubilityincoalbedmethanereservoirs 24 1.54Geertsma’smodelforporosity/transit-time relationship 25 1.55Geothermalgradient 25 1.56HagenPoiseuilleequation 26 1.57HagoortandHoogstragasflowintightreservoirs 26 1.58Hammerlindlmethodforgasinplace 26 1.59High-pressureregiongasflowrate 27 1.60Horizontalwellbreakthroughtime—Withgascap orbottomwater 27
1.61Horizontalwellcriticalratecorrelation—Chaperon 28 1.62Horizontalwellcriticalratecorrelations—Efros 28 1.63Horizontalwellcriticalratecorrelations—Giger andKarcher 29
1.64Horizontalwellcriticalratecorrelations—Joshi methodforgasconing
1.70Ineffectiveporosity
1.72Initialgasinplaceforwater-drivegasreservoirs
1.77Isothermalcompressibilityofoil—Vasquez-Beggs correlation—p > pb
1.78Isothermalcompressibilityofoil—villena-Lanzi correlation—p < pb
1.79Isothermalcompressibilityofwater—Osifcorrelation
1.108Porositydetermination—IESandFDClogs
1.111Pseudo-steadystateproductivityofhorizontal wells—Method1
1.112Pseudo-steadystateproductivityofhorizontal wells—Method2
1.113Pseudo-steadystateproductivityofhorizontal wells—Method3 50
1.114Pseudo-steadystateradialflowequation 50
1.115Relativepermeability—Coreyexponents 51 1.116Remaininggasinplaceincoalbedmethane reservoirs 51
1.117Roachplotforabnormallypressuredgasreservoirs 52
1.118Rockexpansionterminabnormallypressuredgas reservoirs 52
1.119Shapefactor—Earlougher 52
1.120Solutiongasoilratio—Beggs-Standing correlation—p < pb 53
1.121Solutiongasoilratio—Standing’scorrelation 53 1.122Solutiongaswaterratio 54
1.123Somertonmethodforformationpermeabilityin coalbedmethanereservoirs 54
1.124Specificgravityofgashydrateformingcomponents 54
1.125Timetoreachthesemi-steadystateforagaswell inacircularorsquaredrainagearea 55
1.126Timetotheendofinfinite-actingperiodforawell inacircularreservoir 55
1.86Low-pressureregiongasflowratefornon-circular drainagearea
1.87Materialbalanceforcumulativewater influx—HavlenaandOdeh
1.92Oilbubbleradiusofthedrainageareaofeachwell representedbyacircle
1.94Oilformationvolumefactor—Standing’scorrelation
1.95Oilformationvolumefactor—Beggs-standing correlation—p < pb 41
1.41Oilformationvolumefactor—Beggs-standing correlation—p > pb
1.42Oilinplaceforundersaturatedoilreservoirs withoutfluidinjection
1.127TorcasoandWyllie’scorrelationforrelative permeabilityratioprediction
1.128Totalcompressibility
55
56 1.129Totalporevolumecompressibility
56 1.130Transmissibilitybetweencompartments 57 1.131Transmissibilityofacompartment 57 1.132Transmissivity
57
1.133Trappedgasvolumeinwater-invadedzones 58 1.134Two-phaseformationvolumefactor
58
1.135Undergroundfluidwithdrawal—HavlenaandOdeh 59 1.136Verticalwellcriticalratecorrelations—Craft andHawkinsmethod 59
1.137Verticalwellcriticalratecorrelations—Hoyland, Papatzacos,andSkjaeveland—Isotropicreservoirs 60 1.138Verticalwellcriticalratecorrelations—Meyer, Gardner,andPirson—Simultaneousgasandwater coning 60
1.139Verticalwellcriticalratecorrelations—Meyer, Gardner,andPirson—Waterconing 61 1.140Verticalwellcriticalratecorrelations—Meyer, Gardner,andPirson—Gasconing 61
1.141Viscosibility 62
1.142ViscosityofcrudeoilthroughAPI 62
1.143Viscosityofdeadoil—Standing’scorrelation 62 1.144Viscosityofdead-oil—Egbogahcorrelation—p < pb 63
1.145 Viscosityofliveoil—Beggs/Robinsoncorrelation 63 1.146Viscosityofoil—Vasquez/Beggscorrelation—p > pb 63
1.147Viscosityofwateratatmosphericpressure—McCain correlation 64
1.148Viscosityofwateratreservoirpressure—McCain correlation 64
1.149Volumeofgasadsorbedincoalbedmethanereservoirs 64
1.150Volumetricheatcapacityofareservoir 65
1.151Waterbreakthroughcorrelationinvertical wells—BournazelandJeanson 65
1.152Waterbreakthroughcorrelationsinvertical wells—SobocinskiandCornelius 66
1.153Watercontentofsourgas 66
1.154Watercut—Stiles 67
1.155Water-driveindexforgasreservoirs 67
1.1APIgravity
Input(s)
SGo:SpecificGravityofOilPhase(fraction)
Output(s)
API:APIGravity(dimensionless)
Formula(s)
1.156Water-driverecovery 68 1.157Waterexpansiontermingasreservoirs 68 1.158Waterformationvolumefactor—McCaincorrelation 68 1.159Waterinflux—Potaquifermodel 69 1.160WaterinfluxconstantforthevanEverdingen andHurstunsteady-statemodel 69 1.161Watertwo-phaseformationvolumefactor 70 1.162Waxmanandsmitsmodel—Cleansands 70 1.163Welgeextension—Fractionalflow 70
Notes:SGo ¼ roil rwater at60F.
Reference: Wikipedia.org.
1.2Averagepermeabilityforlinearflow—Layeredbeds
Input(s)
k1:PermeabilityforLayer1(mD)
k2:PermeabilityforLayer2(mD)
k3:PermeabilityforLayer3(mD)
A1:AreaofLayer1(ft2)
A2:AreaofLayer2(ft2)
A3:AreaofLayer3(ft2)
Output(s)
kavg:AveragePermeabilityinLinearSystemswhenthereisnocrossflowbetweenlayers(mD)
Formula(s)
Reference: Ahmed,T.(2006).ReservoirEngineeringHandbook.Elsevier,Page:238.
1.3Averagepermeabilityforlinearflow—Seriesbeds
Input(s)
k1:Permeabilityforlayer1(mD)
k2:Permeabilityforlayer2(mD)
k3:Permeabilityforlayer3(mD)
L1:Lengthoflayer1(ft)
L2:Lengthoflayer2(ft)
L3:Lengthoflayer3(ft)
Output(s)
kavg:AveragePermeabilityinLinearSystemsSeries(mD) Formula(s)
Reference: Ahmed,T.(2006).ReservoirEngineeringHandbook.Elsevier,Page:240.
1.4Averagepermeabilityforparallel-layeredsystems
Input(s)
k1:PermeabilityforLayer1(mD)
k2:PermeabilityforLayer2(mD)
k3:PermeabilityforLayer3(mD)
h1:HeightofLayer1(ft)
h2:HeightofLayer2(ft)
h3:HeightofLayer3(ft)
Output(s)
kavg:AveragePermeabilityforParallel-layeredSystems(mD)
Formula(s)
Reference: Ahmed,T.(2006).ReservoirEngineeringHandbook.Elsevier,Page:237.
1.5Averagepermeabilityinradialsystems
Input(s)
ka:Permeabilitybetween rw and ra (mD)
ke:Permeabilitybetween re and ra (mD)
re:Drainageradius(ft)
rw:Wellboreradius(ft)
ra:Radiuslesserthan re (ft)
Output(s)
kavg:AveragePermeabilityinRadialSystemsSeries(mD)
Formula(s)
Reference: AppliedReservoirEngineeringVol.1,Smith,Tracy&Farrar,Equation7–7.
1.6Averagetemperatureofagascolumn
Input(s)
Tt:TubingHeadTemperature(°R)
Tb:WellboreTemperature(°R)
Output(s)
T:ArithmeticAverageTemperature(°R)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:3, Page:199.
1.7Calculationoffractionalflowcurve
Input(s)
mw:WaterViscosity(cP)
krw:RelativePermeabilitytoWater(dimensionless)
kro:RelativePermeabilitytoOil(dimensionless)
mo:OilViscosity(cP)
Output(s)
fw:FractionofTotalFlowingStreamComposedofWater(dimensionless)
Formula(s)
Reference: CraigJr.F.F.,2004,theReservoirEngineeringAspectsofWaterflooding,Vol.3.Richardson,Texas: MonographSeries,SPE,Page:112.
1.8Capillarynumber
Input(s)
mw:ViscosityofDisplacingFluid(cP)
V:CharacteristicVelocity(ft/D)
sow:SurfaceorInterfacialTensionofOilandWaterPhases(dyn/cm)
Output(s)
Nc:CapillaryNumber(dimensionless)
Formula(s)
Reference: Wikipedia.org
1.9Capillarypressure
Input(s)
s:FluidinterfacialTension(dyn/cm)
y:AngleofWettability(degree)
r:RadiusofCapillary(cm)
Output(s)
PC:CapillaryPressure(dyn/cm)
Formula(s)
Reference: Wikipedia.org
1.10Characteristictimeforlineardiffusioninreservoirs
Input(s)
F:Porosity(fraction)
bf:FluidCompressibility(1/psi)
br:RockCompressibility(1/psi)
m:Viscosity(cP)
l:CharacteristicLengthScaleofDiffusion(ft)
k:Permeability(mD)
Output(s)
τ:Time(s)
Formula(s)
Reference: Zoback,M.D.ReservoirGeomechanics,CambridgeUniversityExpress,UK,Page:41.
1.11Coleplot
Input(s)
G:GIP(MSCF)
Eg:GasExpansionTerm(bbl/MSCF)
We:Waterinflux(bbl)
Output(s)
F:UndergroundWaterWithdrawal(bbl)
Formula(s)
¼ G Eg + We
Reference: Ahmed,T.,McKinney,P.D.AdvancedReservoirEngineering,GulfPublishingHouse,Burlington,MA,2015.
1.12Communicationbetweencompartmentsintightgasreservoirs
Input(s)
G:GasinPlace(MSCF)
Eg:GasExpansionTerm(bbl/MSCF)
We:CumulativeWaterInflux(bbl)
Output(s)
F:UndergroundFluidWithdrawal(bbl)
Formula(s)
¼ G Eg + We
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:3, Page:209.
1.13Communicationfactorinacompartmentintightgasreservoirs
Input(s)
K:Permeability(mD)
A:Area(ft2)
T:Temperature(R)
L:LengthofCompartment(ft)
Output(s)
C:CommunicationFactor(SCF/d/psi2/cP)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:3, Page:235.
1.14Compressibilitydriveingasreservoirs
Input(s)
G: Gasinplace(MSCF)
GP:GasProduced(MSCF)
Bg:GasFormationVolumeFactor(MSCF/ft3)
Ef:GasCompressibilityDrive(ft3/MSCF)
Output(s)
CI:CompressibilityIndex(dimensionless)
Formula(s)
Reference: Ahmed,T.&McKinney,P.D.AdvancedReservoirEngineering,GulfPublishingHouse,Burlington,MA,2015.
1.15Correctionfactor—Hammerlindl
Input(s)
G:GasinPlace(MSCF)
Gp:GasProduced(MSCF)
Bg:GasFormationVolumeFactor(bbl/MSCF)
Ef, w:RockandWaterExpansionTerm(bbl/MSCF)
Output(s)
CDI:CompressibilityDriveIndex(dimensionless)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:3, Page:211.
1.16CriticalrateforhorizontalWellsinedge-waterdrivereservoirs
Input(s)
e1:ConstantforC1Equals+0.023or 0.023(dimensionless)
e2:ConstantforC2equals+0.0013or 0.0013(dimensionless)
e3:ConstantforC3equals+0.022or 0.022(dimensionless)
e4:ConstantforC4equals+0.0013or 0.0013(dimensionless)
Dr:DensityDifferencebetweenwaterandoilor,oilandgas(gm/cc)
h:PayZoneThickness(ft)
L:LengthofWell(ft)
xe:DistancebetweenHorizontalWellandConstantPressureBoundary(ft)
mo:OilViscosity(cP)
kh:VerticalPermeability(mD)
kv:HorizontalPermeability(mD)
Output(s)
c1:DimensionlessConstantforcalculation(dimensionless)
c2:DimensionlessConstantforcalculation(dimensionless)
c3:DimensionlessConstantforcalculation(dimensionless)
c4:DimensionlessConstantforcalculation(dimensionless)
qc:DimensionlessCriticalRateperUnitlength(STB/day/ft)
qo:CriticalRate(STB/day)
zc:CriticalHeightRepresentingtheDifferencebetweentheApexoftheGas/WaterCrestfromtheWell Elevation(ft)
Formula(s)
Reference: Joshi,S.D.1991,HorizontalWellTechnology.Tulsa,Oklahoma:PennWellPublishingCompany.Chapter:7, Page:309,310.
1.17Crossflowindex
Input(s)
Npcf:OilRecoveryfromLayeredSystemwithCrossflow(STB)
Npncf:OilRecoveryfromStratifiedSystemwithNoCrossflow(STB)
Npu:OilRecoveryfromUniformSystemwithAveragePermeability(STB)
Output(s)
CI:CrossflowIndex(dimensionless)
Reference: Willhite,G.P.1986.Waterflooding,Vol.3.Richardson,Texas:TextbookSeries,SPE,Chapter:2,Page:166.
1.18Cumulativeeffectivecompressibility—Fetkovich
Input(s)
Swi:InitialWaterSaturation(fraction)
cw :CumulativeTotalWaterCompressibility(1/psi)
M:DimensionlessVolumeRatio(dimensionless)
cf :TotalPV(Formation)Compressibility(psi–1)
Output(s)
ce :EffectiveCompressibility(1/psi)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:3, Page:215,216.
1.19Cumulativegasproduction—Tarner’smethod
Input(s)
N:InitialOil-inPlace(STB)
Rs:GasSolubility(SCF/STB)
Rsi:InitialGasSolubility(SCF/STB)
Bo:OilFormationVolumeFactorattheAssumedReservoirPressure(bbl/STB)
Boi:OilFormationVolumeFactoratInitialReservoirPressure(bbl/STB)
Bg:GasFormationVolumeFactorattheAssumedReservoirPressure(bbl/SCF)
Np:CumulativeOilProduction(STB)
Output(s)
Gp:CumulativeGasProduction(SCF)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:5, Page:340.
1.20Cumulativeoilproduction—Undersaturatedoilreservoirs
Input(s)
N:InitialOil-inPlace(STB)
ce:EffectiveCompressibility(1/psi)
Bo:OilFormationVolumeFactorattheAssumedReservoirPressure(bbl/STB)
Boi:OilFormationVolumeFactoratInitialReservoirPressure(bbl/STB)
DP:PressureDifferential(psi)
Output(s)
Np:CumulativeOilProduction(STB)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:5, Page:333.
1.21Deliverabilityequationforshallowgasreservoirs
Input(s)
k:Permeability(mD)
h:Thickness(ft)
T:Temperature(°R)
m:Viscosity(cP)
z:CompressibilityFactor(dimensionless)
re:RadiusofDrainageArea(ft)
rw:WellboreRadius(ft)
Output(s)
C:PerformanceCoefficient(dimensionless)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:3, Page:287.
1.22Dimensionlesspressure—KamalandBrigham
Input(s)
Q:FlowRate(STB/day)
k:AveragePermeability(mD) h:Thickness(ft)
B:FormationVolumeFactor(bbl/STB)
m:Viscosity(cP)
DP:PressureDifference(psi)
Output(s)
DPd:DimensionlessPressure(dimensionless)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:1, Page:125.
1.23Dimensionlessradiusofradialflow—Constant-rateproduction
Input(s)
r:EffectiveRadius/ReservoirRadius(ft)
rw:WellboreRadius(ft)
Output(s)
rd:DimensionlessRadius(dimensionless)
Formula(s)
Reference: Lee,J.,Rollins,J.B.,&Spivey,J.P.(2003).PressureTransientTesting(Vol.9).Richardson,Texas:Societyof PetroleumEngineers,Page:8.
1.24Dimensionlesstime—MyhillandStegemeier’smethod
Input(s)
Ms:VolumetricHeatCapacityofSteam(btu/ft3 K)
MR:VolumetricHeatCapacityoftheReservoir(btu/ft3 K)
as:OverburdenHeatTransferCoefficient(ft2/d)
ht:ThicknessofColumn(ft)
t:Time(day)
Output(s)
tD:DimensionlessTime(dimensionless)
Formula(s)
Reference: Prats,M.1986.ThermalRecovery.SocietyofPetroleumEngineers,NewYork,Chapter:5,Page:44.
Chapter 113
1.25Dimensionlesstimeforinterferencetestinginhomogeneous reservoirs—Earlougher
Input(s)
k:Permeability(mD)
ø:Porosity(fraction)
t:Time(h)
k:OverallProduction(mD)
m:Viscosity(cP)
ct:TotalCompressibility(1/psi)
rw:WellboreRadius(ft)
Output(s)
tD:DimensionlessTime(dimensionless)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:1, Page:117.
1.26Dimensionlessverticalwellcriticalratecorrelations—Hoyland,Papatzacos, andSkjaeveland
Input(s)
h:OilColumnThickness(ft)
kh:EffectiveOilPermeability(mD)
rw:WaterDensity(g/cc)
mo:OilViscosity(cP)
ro:OilDensity(g/cc)
Bo:OilFormationVolumeFactor(RB/STB)
qo:CriticalOilRate(STB/day)
Output(s)
QoD:DimensionlessCriticalRate(dimensionless)
Formula(s)
Reference: ReservoirEngineeringHandbook,FourthEdition,Ahmed,Page:607.
1.27Dimensionlesswellborestoragecoefficientofradialflow—Constant-rate production
Input(s)
h:ReservoirThickness(ft)
C:WellboreStorageCoefficient(STB/psi)
Ø:Porosity(fraction)
ct:TotalCompressibility(1/psi)
rw:WellboreRadius(ft)
Output(s)
Cd:DimensionlessWellbore-StorageCoefficient(dimensionless)
Formula(s)
Reference: Lee,J.,Rollins,J.B.,&Spivey,J.P.(2003).PressureTransientTesting(Vol.9).Richardson,Texas:Societyof PetroleumEngineer,Page:8.
1.28Effectivecompressibilityinundersaturatedoilreservoirs—Hawkins Input(s)
Soi:InitialOilSaturation(fraction)
Swi:InitialWaterSaturation(fraction)
co:OilCompressibility(1/psi)
cw:WaterCompressibility(1/psi)
cf:FormationCompressibility(1/psi)
Output(s)
ce:EffectiveCompressibility(1/psi)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:5, Page:334.
1.29Effectivewellboreradiusofahorizontalwell—Method1—Anisotropicreservoirs Input(s)
L:HorizontalWellLength(ft)
h:PayZoneThickness(ft)
rw:WellboreRadius(ft)
kh:HorizontalPermeability(mD)
kv:VerticalPermeability(mD)
A:DrainageArea(acre)
Output(s)
reh:EffectiveDrainageRadius(ft)
a:HorizontalwellborevariablefromJoshi(dimensionless)
b:PermeabilityRatioconstant(dimensionless)
rwd:EffectiveWellboreRadius(ft)
Reference: HorizontalWellTechnology,Joshi,Page:90.
1.30Effectivewellboreradiusofahorizontalwell—Method1—Isotropic reservoirs
Input(s)
L:HorizontalWellLength(ft)
h:PayZoneThickness(ft)
rw:WellboreRadius(ft)
kh:HorizontalPermeability(mD)
kv:VerticalPermeability(mD)
A:DrainageArea(acre)
Output(s)
reh:EffectiveDrainageRadius(ft)
a:HorizontalwellborevariablefromJoshi(dimensionless)
rwd:EffectiveWellboreRadius(ft) Formula(s)
Reference: HorizontalWellTechnology,Joshi,Page:90.
1.31Effectivewellboreradiusofahorizontalwell—vanderVlisetal.method
Input(s)
h:PayZoneThickness(ft)
rw:WellboreRadius(ft)
a:SlantAngle(degrees)
Output(s)
L:LengthofSlantWellbore(ft)
rw:EffectiveWellboreRadius(ft)
Formula(s)
Reference: Joshi,S.D.1991,HorizontalWellTechnology.Tulsa,Oklahoma:PennWellPublishingCompany.Chapter:3, Page:96.
1.32Effectivewellboreradiusofawellinpresenceofuniform-fluxfractures
Input(s)
xf:FractureHalfLength(ft)
e:LogarithmicConstant ¼ 2.718(dimensionless)
Output(s)
rw:EffectiveWellboreRadius(ft)
Formula(s)
Reference: Joshi,S.D.1991,HorizontalWellTechnology.Tulsa,Oklahoma:PennWellPublishingCompany.Chapter:5, Page:135.
1.33Effectivewellboreradiustocalculateslantwellproductivity—vanderVlisetal.
Input(s)
h:PayZoneThickness(ft)
rw:WellboreRadius(ft) a:SlantAngle(degrees)
Output(s)
L:LengthofSlantWellbore(ft)
rw:EffectiveWellboreRadius(ft)
Formula(s)
Reference: Joshi,S.D.1991,HorizontalWellTechnology.Tulsa,Oklahoma:PennWellPublishingCompany.Chapter:3, Page:96.
1.34Estimationofaveragereservoirpressure—MDHmethod
Input(s)
pws:Shut-InPressure(psi)
pDMDH:MDHPressure(dimensionless)
m:Semi-logStraightLineoftheMDHPlot(psi/cycle)
Output(s)
Pr:AverageReservoirPressure(psi)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:1, Page:59.
1.35Formationtemperatureforagivengradient
Input(s)
Ts:TemperatureNearSurface(degree °F)
D:TotalDepth(ft)
gG:GeothermalGradient(degree °F/100ft)
Output(s)
Tf:FormationTemperature(degree °F)
Formula(s)
Reference: Bassiouni,Z.,1994,Theory,Measurement,andInterpretationofWellLogs.SPETextbookSeriesVol.4. Chapter4,Page:75.
1.36Fractionofthetotalsolutiongasretainedinthereservoirasfreegas
Input(s)
N:OilinPlace(STB)
Rp:ProducedGas-OilRatio(SCF/STB)
Np:CumulativeOilProduction(STB)
Rsi:InitialGasSolubility(SCF/STB)
Rs:GasSolubility(SCF/STB)
Output(s)
ag:RetainedGasVolumeoftheTotalGas(fraction)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:4, Page:314.
1.37Fractionalgasrecoverybelowthecriticaldesorptionpressureincoal bedmethanereservoirs
Input(s)
Vm:Langmuir(constant)
Gc:GasContentatCriticalDesorptionPressure(SCF/ton)
b:Langmuir(constant)
P:PressureofReservoir(psi)
a:RecoveryExponent(dimensionless)
Output(s)
RF:RecoveryFactor(fraction)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:3, Page:223.
1.38Freegasinplace
Input(s)
A:DrainageArea(acres)
h:Thickness(ft)
Ø:Porosity(fraction)
Swi:InitialWaterSaturation(fraction)
Egi:GasExpansionFactoratInitialReservoirPressure(SCF/bbl)
Output(s)
Gf:OriginalFreeGas-in-Place(SCF)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:3, Page:227.
1.39Gasadsorbedincoalbedmethanereservoirs
Input(s)
A:Area(acres)
h:Height(ft)
r
b:Density(g/cc)
V:AdsorptionGas(SCF/ton)
Output(s)
Ga:GasAdsorbed(SCF)
Formula(s)
Reference: Ahmed,T.&McKinney,P.D.AdvancedReservoirEngineering,GulfPublishingHouse,Burlington,MA,2015.
1.40Gasbubbleradius
Input(s)
A:DrainageArea(acres)
h:Thickness(ft)
sB:Bulk(g/cc)
Gc:GasContent(SCF/ton)
Output(s)
G:Gas-in-Place(SCF)
Formula(s)
Reference: Ahmed,T.,McKinney,P.D.2005.AdvancedReservoirEngineering,GulfPublishingofElsevier,Chapter:3, Page:227.
1.41Gascapratio
Input(s)
G:InitialGasCapVolume(SCF)
Bgi:InitialGasFormationVolumeFactor(bbl/SCF)
N:InitialOilinPlace(STB)
Boi:InitialOilFormationVolumeFactor(bbl/STB)
Output(s)
m:GasCapRatio(dimensionless)
Formula(s)
Reference: Ahmed,T.,McKinney,P.AdvancedReservoirEngineering,GulfPublishingHouse,Burlington,MA,2015, Chapter:4,Page:317.
