Petrophysical Formulae
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Transcript of Petrophysical Formulae
POROSITY• Effective Porosity
• PHIE = PHIA * (1-Vshl)
• Density Porosity
• PHID = (RhoM - RHOB) / (RhoM - RhoF)
• Average Neutron Density Porosity
• PHIA = (PHID + PHIN) / 2
• Gamma Ray Neutron Porosity
• Enter Values for PorMax, PorMin...
• PorMax = 0.35
• PorMin = 0.02
• Enter Values in Counts Per Second or API...
• CPS_PorMax = 75
• CPS_PorMin = 600
• B = log(PorMax/PorMin) / (CPS_PorMax - CPS_PorMin)
• A = PorMax / 10 ^ (B*CPS_PorMax)
• PHIGRN = A * 10 ^ (B * CPS)
• Sonic Porosity (Wyllie)
• PHIS = (DT - DTma) / (DTfld - DTma)
• Sonic Porosity (Wyllie)
• Enter Compaction Coefficient below,
• Cmp = 1.0
• PHIS = (1/Cmp) * (DT - DTma) / (DTfld - DTma)
• Sonic Porosity (Empirical)
• PHIS = 0.67 * (DT - DTma) / DT
• Apparent Sonic Matrix
• DTma = ( DT - PHIA * DTfld ) / (1 - PHIA)
• Apparent Density Matrix
• RHOMa = (RHOB - PHIA * RhoF) / (1 - PHIA)
• Bulk Volume Water
• BVW = PHIA * SwA.
• Hydrocarbon Pore Volume
• HCPV = (1-SwA) * PHIA
• Hydrocarbon Pore Volume
• SoPhiH = (1-SwA) * PHIA
WATER RESISTIVITY
• Archie Ro
• Ro = a * Rw / (PHIA^m)
• Apparent Water Resistivity
• Rwa = RT * PHIA^m
• Conductivity
• COND = 1000/RT
• Rw from Dual Water
• RwDW = Rw * RwBnd / (Rw * Vshl + (1-Vshl) * RwBnd)
• Ro from Dual Water
• RoDW = (1 / (PHIA^m)) * (Rw * RwBnd / (Rw * Vshl + RwBnd * (1 - Vshl)))
• Modified Simandoux Ro
• If (Vshl < 1)
• RoMS = 1/(PHIE^m / (a* Rw*(1-Vshl)) + Vshl/Rshl)
• Resistivity Temp Correction
• T1 and T2 in 'F
• R2 = R1 * (T1 + 6.77) / (T2 + 6.77)
• Resistivity Temp Correction
• T1 and T2 in 'C
• R2 = R1 * (T1 + 21.5) / (T2 + 21.5)
WATER SATURATION
• Archie Water Saturation
• SwA = sqrt( Rw / (RT * PHIA^2) )
• Archie Water Saturation
• SwA = (a * Rw / ( RT * PHIA^m) )^(1/n)
• Archie Water Saturation (Humble)
• SwA = sqrt( .62 * Rw / (RT * PHIA ^2.15) )
• Archie Water Saturation
• SwA = sqrt( Rw / (RT * PHID ^m) )
• Archie Water Saturation
• SwA = sqrt(Ro / RT)
• Archie Water Saturation
• SwA = sqrt(Rw / Rwa)
• SwA = min( 1, max( 0, SwA )
• Dual Water SwT & SwE
• Calculate SwT Total Porosity
• Y = Vshl * ( RwBnd - Rw ) / ( 2 * RwBnd )
• SwT = Y +( (Rw / ( RT * PHIA^2 ) ) + Y^2 )^.5
• SwT = min( 1, max( Vshl, SwT ) )
• Calculate SwE Effective Porosity
• If ( Vshl < .75 )
• SwE = ( SwT - Vshl ) / ( 1 - Vshl )
• Modified Simandoux SwMS
• If (Vshl < 1)
• SwMS = (sqrt( (Vshl/Rshl)^2 + 4*PHIE^m/(a*Rw*(1-Vshl)*RT) ) - Vshl/Rshl)/(2*PHIE^m/(a*Rw*(1-Vshl)) )
• Indonesian SwI
• SwI = sqrt(1/RT) / ( Vshl^(1- 0.5*Vshl) /sqrt(Rshl) + sqrt( PHIE^m / (a*Rw)) )
• Ratio Method Sw
• Requires normalized SP,
• Rmf/Rw ratio from SP...
• K = ~ 61 + 0.1333 * <Temp>
• K = -71
• RmfRwRatio = 10 ^ (SP / K)
• Sw = Min( 1, ( (ResS/ResD) / (RmfRwRatio) ) ^(5/8) )
• Vshl = min(1, max(0, (GR-GRcln) / (GRshl-GRcln) ))
• Vshl = min(1, max(0, (SP-SPcln) / (SPshl-SPcln) ))
• Vshl = min(1, max(0, (RHOB - RhoM + PHIN * (RhoM - RhoF)) / (RhoShl - RhoM +HIshl * (RhoM - RhoF)) ))
SHALE VOLUME
• Calculate Vshl from Minimum of GR, SP & N/D
• Vshl_GR = (GR-GRcln) / (GRshl-GRcln) )
• Vshl_SP = (SP-SPcln) / (SPshl-SPcln) ))
• Vshl_ND = (RHOB - RhoM + PHIN * (RhoM - RhoF)) / (RhoShl - RhoM +HIshl * (RhoM - RhoF)
• Vshl = Min(Vshl_GR , Min( Vshl_SP , Vshl_ND ))
• Clavier Shale Correction
• Vshl = 1.7 - (3.38 - (Vshl+0.7)^2)^0.5
• Steiber Shale Correction
• Vshl = 0.5 * Vshl / (1.5 - Vshl)
DT EQUATIONS
• Faust's Equation for DT
• DT_F = 1000/(2 * (DEPTH * RT) ^(1 / 6))
• Gardner's Equation for DT
• DT_G = ((25 / RHOB) ^4) /140
• Sonic from Apparent Porosity
• DT_P = DTma + PHIA * ( DTfld - DTma)
• Sonic 3pt Average Curve
• DTAve = (DT [-1] + DT + DT[1])/3
• Sonic 5pt Average Curve
• DTAve = (DT[-2] + DT[-1] +DT + DT[1] + DT[2])/5
• Sonic 7pt Average Curve
• DTAve = (DT[-3] + DT[-2] + DT[-1] +DT + DT[1] + DT[2]+ DT[3])/7
PERMEABILITY
• Tixier Permeability
• K = (250 * PHIE^3/SwIrr)^2
• Timur Permeability
• K = (100 * PHIE^2.25/SwIrr)^2
• Coates Permeability
• K = (70 * PHIE^2 * (1- SwIrr)/SwIrr)^2
MISCELLANEOUS• Oil in Barrels; Depth in Feet
• BBL = 7758 * Acres * PHIA * (1 - SwA)
• Gas in Mcfd; Depth in Feet
• MCF = 43.560 * Acres * PHIA * (1 - SwA)
• Oil in Barrels; Depth in Meters
• BBL = 25450 * Acres * PHIA * (1 - SwA)
• Gas in Mcfd; Depth in Meters
• MCF = 142.9 * Acres * PHIA * (1 - SwA)
• Oil in Barrels; Depth in Meters
• BBL = 62890 * Hectares * PHIA * (1 - SwA)
• Gas in Mcfd; Depth in Meters
• MCF = 353.1 * Hectares * <Step> * PHIA * (1 - SwA)
• Oil in Barrels with Pay criteria
• If (PAY >0)
• BBL = 7758 * Acres * PHIA * (1 - SwA)
• Gas in Mcfd with PAY criteria
• If (PAY >0)
• MCF = 43.560 * Acres * PHIA * (1 - SwA)
