GAS CONDENSATE & VOLATILE OIL BASIC WORKFLOW …cloud1.activelearner.com/.../PetroAcademy/RES-RFF/...BASIC WORKFLOW EQUATIONS Reservoir Fluid Fundamentals Richard Henry [email protected]

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

Reservoir Fluid Fundamentals ═════════════════════════════════════════════════════════════════════════

© PetroSkills, LLC. All rights reserved._____________________________________________________________________________________________

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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


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


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]



.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 [ ] [ ]


.ppc pseudo‐critical pressure [psia] [kPa]

.Tpc pseudo‐critical temperature [oR] [K]

.a00‐>b03 are constants



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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]



.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]



.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]


.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


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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GAS CONDENSATE & VOLATILE OIL BASIC WORKFLOW …cloud1.activelearner.com/.../PetroAcademy/RES-RFF/...BASIC WORKFLOW EQUATIONS Reservoir Fluid Fundamentals Richard Henry [email protected]

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