Transcript PETROPHYSICAL FORMULAE

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