gas condensate & volatile oil basic workflow...
TRANSCRIPT
GAS CONDENSATE &
VOLATILE OIL
BASIC WORKFLOW
EQUATIONS Reservoir Fluid Fundamentals
Richard Henry [email protected]
Abstract A collection of equations used during basic workflows on gas condensates and volatile oils
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Contents Dew Point ...................................................................................................................................................... 2
SI Conversions ........................................................................................................................................... 2
Output ................................................................................................................................................... 2
Input ...................................................................................................................................................... 2
Solution Condensate‐Oil Ratio ...................................................................................................................... 3
SI Conversions ........................................................................................................................................... 3
Output ................................................................................................................................................... 3
Input ...................................................................................................................................................... 3
Gas Density ................................................................................................................................................... 4
SI Conversions ........................................................................................................................................... 5
Output ................................................................................................................................................... 5
Input ...................................................................................................................................................... 5
Oil Density ..................................................................................................................................................... 5
SI Conversions ........................................................................................................................................... 6
Output ................................................................................................................................................... 6
Input ...................................................................................................................................................... 6
Gas Formation Volume Factor ...................................................................................................................... 6
Oil Formation Volume Factor ........................................................................................................................ 6
Two‐Phase Deviation Factor ......................................................................................................................... 7
Macros .......................................................................................................................................................... 8
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Dew Point ln 𝑝 𝑎 𝑎 𝑋 𝑎 𝑋
𝑋 𝑋
𝑋 𝑎 𝑎 𝑋 𝑎 𝑋
𝑋 ln𝑅 , 𝛾 , 𝛾
Equation 1: Ovalle et al. dew point pressure correlation
Where: Oilfield
.pd dew point pressure [psia]
.Rs separator gas‐stock tank oil ratio [scf/stb]
.γAPI stock tank oil specific gravity [oAPI]
.γgR reservoir gas specific gravity [1/air]
. .a00‐a32 are constants, X0‐>X2 are intermediate variables
Constant Value Constant Value
a00 8.48 a20 ‐0.87528
a01 0.32239 a21 ‐0.29709
a02 0.00477 a22 ‐2.9145
a10 9.8895 a30 ‐0.01691
a11 11.7 a31 0.00151
a12 3.5202 a32 ‐0.81744
SI Conversions
Output p kPa p psi 0.145037738
Input
Rscfstb
R𝑠msm
5.61458
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Solution Condensate‐Oil Ratio
𝑅 𝑝 𝑅 1 𝑋 𝑋 1𝑝𝑝
𝑋 𝑎 𝑎 𝑅 if 𝑅 𝑎
𝑋 𝑎 1 𝑎 𝑅 𝑎 if 𝑅 𝑎
𝑋 𝑎 𝑎 𝑅 if 𝑅 𝑎
𝑋 𝑎 ln 𝑅 𝑎 if 𝑅 𝑎
Equation 2: Garb's correlation for solution condensate‐oil ratio below the dew point
Where: Oilfield
.p pressure of interest [psia]
.pi dew point pressure [psia]
.Rvi condensate‐gas solution ratio at dew point pressure [stb/MMscf]
.Rv(p) condensate‐gas solution ratio at pressure of interest [stb/MMscf] .X0 and X1 are intermediate variables
.a00‐>a31 are constants
Constant Value Constant Value
a00 24.5 a10 4.05
a01 ‐1.37 a11 0.0099
a02 3.91 a12 1.48
a03 2.71 a13 24.3
a04 ‐15 a14 ‐101
a05 ‐0.129 a30 15
a31 150
SI Conversions
Output
Rsmsm
Rstb
MMscf5.61458 1000 1000
Input
Rstb
MMscfR
smsm
1000 1000 5.61458
p psia p kPa 0.145037738
p psia p kPa 0.145037738
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Gas Density
𝜌𝑀 𝑝𝑍𝑅𝑇
Equation 3: Gas density from the real gas equation
Z 𝑎𝑏𝑜𝑢_𝑍 𝑝 , 𝑇 , 1
𝑝𝑝𝑝
𝑇𝑇𝑇
Equation 4: Compressibility factor of the in‐situ gas
𝑀 𝑦 𝑀 𝑦 𝑀
Equation 5: Apparent molecular mass of the in‐situ gas
𝑝 𝑎 𝑎 𝑀 𝑎 𝑀 ln 𝑀 𝑎
𝑇 𝑏 𝑏 𝑀 𝑏 𝑀 ln 𝑀 𝑏
Equation 6: Sutton's correlations for pseudo‐critical oil properties (works for gas)
Where: Oilfield SI
.ρg In‐situ gas density [lb/cuft] [kg/m3]
.Mw apparent molecular mass of the in‐situ gas [lb/mol] [g/mol]
.Mwo apparent molecular mass of the stock‐tank oil [lb/mol] [g/mol]
.Mwg apparent molecular mass of the surface gas [lb/mol] [g/mol]
.yg Mole fraction of surface gas in in‐situ gas [ ] [ ]
.yo Mole fraction of stock‐tank oil in in‐situ gas [ ] [ ]
.p pressure of interest [psia] [kPa]
.T temperature of interest [oR] [K]
.Z compressibility factor of in‐situ gas [ ] [ ]
.R universal gas constant [[psia.cuft]/[mol.oR]] [J/mol/K]
.ppc pseudo‐critical pressure [psia] [kPa]
.Tpc pseudo‐critical temperature [oR] [K]
.a00‐>b03 are constants
Constant Value Constant Value
a00 768.1 b00 135.6
a01 ‐4.919 b01 10.864
a02 1.302 b02 ‐2.81
a03 ‐3.366 b03 ‐3.366
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SI Conversions
Output Ppc [kPa] = Ppc [psia] ÷ 0.145037738
Tpc [K] = Tpc [oR] ∙ 5 ÷ 9
Input Mw [lb/mol] = Mw [g/mol] ÷ 1
Oil Density
𝜌𝑀 𝑝𝑍𝑅𝑇
Equation 7: Oil density from the real gas equation
Z 𝑎𝑏𝑜𝑢_𝑍 𝑝 , 𝑇 , 0.01
𝑝𝑝𝑝
𝑇𝑇𝑇
Equation 8: Compressibility factor of the in‐situ oil
𝑀 𝑥 𝑀 𝑥 𝑀
Equation 9: Apparent molecular mass of the in‐situ oil
𝑝 𝑎 𝑎 𝑀 𝑎 𝑀 ln 𝑀 𝑎
𝑇 𝑏 𝑏 𝑀 𝑏 𝑀 ln 𝑀 𝑏
Equation 10: Sutton's correlations for pseudo‐critical oil properties
Where: Oilfield SI
.ρo In‐situ oil density [lb/cuft] [kg/m3]
.Mw apparent molecular mass of the in‐situ oil [lb/mol] [g/mol]
.Mwo apparent molecular mass of the stock‐tank oil [lb/mol] [g/mol]
.Mwg apparent molecular mass of the surface gas [lb/mol] [g/mol]
.xg Mole fraction of surface gas in in‐situ oil [ ] [ ]
.xo Mole fraction of stock‐tank oil in in‐situ oil [ ] [ ]
.p pressure of interest [psia] [kPa]
.T temperature of interest [oR] [K]
.Z compressibility factor of in‐situ oil [ ] [ ]
.R universal gas constant [[psia.cuft]/[mol.oR]] [J/mol/K]
.ppc pseudo‐critical pressure [psia] [kPa]
.Tpc pseudo‐critical temperature [oR] [K]
.a00‐>b03 are constants
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Constant Value Constant Value
a00 768.1 b00 135.6
a01 ‐4.919 b01 10.864
a02 1.302 b02 ‐2.81
a03 ‐3.366 b03 ‐3.366
SI Conversions
Output ppc [kPa] = ppc [psia] ÷ 0.145037738
Tpc [K] = Tpc [oR] ∙ 5 ÷ 9
Input Mw [lb/mol] = Mw [g/mol] ÷ 1
Gas Formation Volume Factor
𝐵𝑀𝜌
𝜌
𝑀1𝑦
Equation 11: Gas formation volume factor from density
𝑀 𝑦 𝑀 𝑦 𝑀
Equation 12: Apparent molecular mass of the in‐situ gas
Where: Oilfield SI
.ρg In‐situ gas density [lb/cuft] [kg/m3]
.ρgsc surface gas density at standard conditions [lb/scf] [kg/sm3]
.Mw apparent molecular mass of the in‐situ gas [lb/mol] [g/mol]
.Mwo apparent molecular mass of the stock‐tank oil [lb/mol] [g/mol]
.Mwg apparent molecular mass of the surface gas [lb/mol] [g/mol]
.yg Mole fraction of surface gas in in‐situ gas [ ] [ ]
.yo Mole fraction of stock‐tank oil in in‐situ gas [ ] [ ]
Oil Formation Volume Factor
𝐵𝑀𝜌
𝜌𝑀
1𝑥
Equation 13: Oil formation volume factor from density
𝑀 𝑥 𝑀 𝑥 𝑀
Equation 14: Apparent molecular mass of the in‐situ oil
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Where: Oilfield SI
.ρo In‐situ oil density [lb/cuft] [kg/m3]
.ρosc surface oil density at standard conditions [lb/scf] [kg/sm3]
.Mw apparent molecular mass of the in‐situ oil [lb/mol] [g/mol]
.Mwo apparent molecular mass of the stock‐tank oil [lb/mol] [g/mol]
.Mwg apparent molecular mass of the surface gas [lb/mol] [g/mol]
.xg Mole fraction of surface gas in in‐situ oil [ ] [ ]
.xo Mole fraction of stock‐tank oil in in‐situ oil [ ] [ ]
Two‐Phase Deviation Factor 𝑝 𝑉 𝑉 𝑍 𝑛 𝑛 𝑅𝑇
Equation 15: Two‐phase deviation factor definition
Where: Oilfield SI
.Vo oil phase in‐situ volume [cuft] [m3]
.Vg gas phase in‐situ volume [cuft] [m3]
.no oil phase in‐situ moles [lb‐mol] [g‐mol]
.ng gas phase in‐situ moles [lb‐mol] [g‐mol]
.p in‐situ pressure [psia] [kPa]
.T in‐situ temperature [oR] [K]
.R universal gas constant [[psia.cuft]/[mol.oR]] [J/mol/K]
.Z2p two‐phase deviation factor [ ] [ ]
𝑍 𝑎 𝑎 𝑝𝑎𝑇
𝑎 𝑝𝑎𝑇
𝑎𝑝𝑇
Equation 16: Two‐phase deviation factor correlation
Where: Oilfield SI
.ppr pseudo‐reduced gas phase pressure [ ] [ ]
.Tpr pseudo‐reduced gas phase temperature [ ] [ ]
.Z2p two‐phase deviation factor [ ] [ ]
.a0‐>a5 are constants
Constant Value Constant Value
a0 2.24353 a3 0.000829231
a1 ‐0.0375281 a4 1.53428
a2 ‐3.5639 a5 0.131987
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Macros Name Purpose Qualifier Units Source Date Module
oval_Pd Dew Point Pressure
Gas [psia] Ovalle, Lenn & McCain 2005 Wet
garb_rv Volatized oil‐gas ratio
Gas [stb/MMscf] Garb 1978 Wet
raye_Z2 Z‐Factor 2‐phase [ ] Rayes, Piper, McCain & Poston
1992 Wet
sutt_rob Density Oil or Gas
[lb/cuft] Sutton 2006 Oil
suttopc Critical Pressure Oil or Gas
[psia] Sutton 2006 Z
suttoTc Critical Temperature
Oil or Gas
[oF] Sutton 2006 Z
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