1. INSTRUCTOR © 2017, John R. Fanchi
All rights reserved. No part of this manual may be reproduced in any form without the express written permission of the author.
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

2. To the Instructor
The set of files here are designed to help you prepare lectures for your own course using the text Introduction to Petroleum Engineering, J.R. Fanchi and R.L. Christiansen (Wiley, 2017)
File format is kept simple so that you can customize the files with relative ease using your own style. You will need to supplement the files to complete the presentation topics.

3. FLUID PROPERTIES © 2017, John R. Fanchi
All rights reserved. No part of this manual may be reproduced in any form without the express written permission of the author.
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

4. Outline Origin of Fossil Fuels Oilfield Fluids Fluid Properties
Fluid Modeling
Homework: IPE Ch. 3

5. ORIGIN OF FOSSIL FUELS
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

6. Formation of Petroleum
Biogenic Theory

7. Chemical Basis of Fossil Fuels
Petroleum Composition
Biochemistry

8. OILFIELD FLUIDS
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

9. Chemical Composition Natural Gas C = 65% - 80% H = 1% - 25%
Crude Oil
C = 84% - 87%
H = 11% - 15%
S = 0.06% - 2%
N = 0.1% - 2%
O = 0.1% - 2%
Crude Oil
C5H12

10. Petroleum Composition
Predominantly paraffins, napthenes, and aromatics because of the relative stability of the molecules.
PARAFFINS
Saturated hydrocarbons (single bond between carbons)
e.g. methane, ethane
General chemical formula is CnH2n+2

11. Petroleum Composition (cont.)
NAPTHENES
Saturated hydrocarbons with a ringed structure
e.g. cyclopentane
General chemical formula is CnH2n
AROMATICS
Unsaturated hydrocarbons with a ringed structure (multiple bonds between carbons)
e.g. benzene
Unique ring structure allows aromatics to be relatively stable and unreactive

12. Impact of Sulfur on Refineries
Sour crude
> 1% sulfur
Sulfur must be removed
Sulfur can damage refinery equipment
1% sulfur
Sulfur does not need to be removed
Sweet crude < 1% sulfur

13. API Gravity Fluid °API Fresh water 10 Heavy oil < 25 Average oil
Light oil

14. Benchmark Crude Oil West Texas Intermediate 38 - 40°API (light oil)
0.3% sulphur (sweet crude)

15. Natural Gas Composition
Weight %
Methane
CH4
70% - 98%
Ethane
C2H6
1% - 10%
Propane
C3H8
trace - 5%
Butane
C4H10
trace - 2%

16. FLUID PROPERTIES
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

17. p-T Diagram for Ethane

18. p-T Diagram for Ethane and n-Heptane
vapor pressure curves for ethane and n-heptane
phase envelope for mixture of 59 mol% ethane and 41 mol% n-heptane

19. p-T Diagram Nomenclature
data for 59 mol% ethane and 41 mol% n-heptane mixture

20. p-T Phase Diagram

21. Typical Molar Compositions
(after Pedersen, et al., 1989)
Component
Gas
Gas Condensate
Volatile Oil
Black Oil N2
CO2 C1 C2 C3
iC4+nC4
iC5+nC5
iC6+nC6
0.3
1.1
90.0
4.9
1.9
0.4
C6+: 0.3
0.71
8.65
70.86
8.53
4.95
2.00
0.81
0.46
1.67
2.18
60.51
7.52
4.74
4.12
2.97
1.99
0.67
2.11
34.93
7.00
7.82
5.48
3.80
3.04 C7 C8 C9
C10
C11
C12
0.61
0.39
0.28
0.20
0.15
2.45
2.41
1.69
1.42
1.02
C12+: 5.31
4.39
4.71
3.21
1.79
1.72
1.74
C13
C14
C15
C16
C17
0.11
0.10
0.07
0.05
C17+: 0.37
1.35
1.34
1.06
C18
C19
C20
1.00
0.90
C20+: 9.18

22. Classification of Oil and Gas using p-T diagrams
Fluid Type
Dominant Phase in Reservoir
Reservoir Temperature
Phases at Separator Pressure and Temperature
Black Oil
Liquid
Far to the left of the critical point
Liquid and Gas
Volatile Oil
Left of, but close to, the critical point
Retrograde Gas
Gas
Between critical point and cricondentherm
Wet Gas
Right of the cricondentherm
Dry Gas

23. Classification of Oil and Gas by Generally Available Properties

24. Classifying Hydrocarbon Liquid Types Using API Gravity and Viscosity
(degrees API)
Viscosity
(centipoises)
Water 10
1 cp
Extra heavy oil
4 to 10
< 10,000 cp
Bitumen
> 10,000 cp

25. Properties of Gas Mixtures Number of Moles
Calculate n (number of lb moles) as
where
Wi = weight of component i (lbs)
Mi = molecular weight of component i (lbs/lb mole)

26. Mole Fraction Calculate mole fraction as where
yi = mole fraction of component i in gas phase
NC = number of components

27. Pure Ideal Gas: Weight 𝑝𝑉=𝑛𝑅𝑇 𝑊=𝑛𝑀= 𝑝𝑉 𝑅𝑇 𝑀 Ideal gas law where
p = pressure [psia = psig]
V = volume [cu. ft.]
n = number of lb moles
R = gas content = psia cu. ft./lb mole °R
T = temperature [°R = °F]
𝑊=𝑛𝑀= 𝑝𝑉 𝑅𝑇 𝑀
Then
where
W = weight [lbs]
M = molecular weight [lbs/lb mole]

28. Pure Ideal Gas: Density
Density of an ideal gas
𝜌 𝑔 = 𝑊 𝑉 = 𝑝𝑀 𝑅𝑇
Where g = density [lb/cu. ft.]

29. Ideal Gas Mixture: Molecular Weight
Apparent molecular weight Ma
where
Nc = number of components
yi = mole fraction of component i
Mi = molecular weight of component i [lbs/lb mole]

30. Ideal Gas Mixture: Specific Gravity
Specific gravity of gas

31. Gas Heating Value Gas Heating Value Hm of a mixture: where
Nc = number of components
yi = mole fraction of component i
Hi = heating value of component i [Btu/cu ft]

32. Ideal Gross Heating Values
COMPONENT
IDEAL GROSS HEATING VALUE (Btu/cu ft)* N2
CO2 C1
1009.7 C2
1768.8 C3
2517.5
i-C4
3252.7
n-C4
3262.1
i-C5
4000.3
n-C5
4009.6 C6
4756.2
* Source: Gas Processors Assn. Manual of Pet. Measurements

33. Gas Heating Value Example
COMP.
Hi (Btu/cu ft)* yi
yi*Hi (Btu/cu ft) N2
0.0030
CO2
0.0042 C1
1009.7
0.9115
920 C2
1768.8
0.0510 90 C3
2517.5
0.0157 39
i-C4
3252.7
0.0038 12
n-C4
3262.1
0.0049 16
i-C5
4000.3
0.0020 8
n-C5
4009.6
0.0012 5 C6
4756.2
0.0011
C7+
5400.0
0.0016 9
Total
1.0000
1104

34. Ideal Gas Mixture: Equilibrium K-Value
Define as ratio of separator gas (yi) to separator liquid (xi) mole fractions:
Pure gas: Ki  
Pure liquid: Ki  0

35. Gas Compressibility Factor
Real gas law
𝑝𝑉=𝑍𝑛𝑅𝑇
where Z is gas compressibility factor.
Estimate Z:
EoS
Standing and Katz chart: Z is a function of pseudoreduced temperature and pseudoreduced pressure

36. Alternative Form of Real Gas Law
pc and Tc denote temperature and pressure at critical point
𝑣 =𝑀𝑣; 𝑣=𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑣𝑜𝑙𝑢𝑚𝑒 𝑒.𝑔. 𝑚 3 𝑘𝑔 = 1 𝜌 ;𝜌= 𝑚 𝑉 =𝑑𝑒𝑛𝑠𝑖𝑡𝑦;
M = molecular weight, m = mass, V = volume
8.314 kJ/kmol∙K
1.986 Btu/lbmol∙oR
1545 ft∙lbf/lbmol∙oR
= universal gas constant

37. Gas Formation Volume Factor
Real gas law
𝑝𝑉=𝑍𝑛𝑅𝑇
Let r denote reservoir conditions and s denote standard conditions. Gas FVF is
𝐵 𝑔 = 𝑉 𝑟 𝑉 𝑠 = 𝑝 𝑠 𝑝 𝑟 𝑇 𝑟 𝑇 𝑠 𝑍 𝑟 𝑍 𝑠
Define {ps = 14.7 psia, Ts = 60°F = 520°R, Zs = 1}
Calculate
𝐵 𝑔 = 𝑇 𝑟 𝑍 𝑟 𝑝 𝑟

38. PVT - Gas

39. Multi-Stage Flash of Oil-Gas Well Stream

40. PVT - Oil

41. Example: Dissolved (Solution) GOR
bubble-point pressure PB = 1851 psia
reservoir temperature = 220˚F
oil gravity = 35˚API
gas gravity = 0.68
gas dissolved in oil = 350 SCF/STB at PB

42. Example: Oil FVF bubble-point pressure PB = 1851 psia
reservoir temperature = 220˚F
oil gravity = 35˚API
gas gravity = 0.68
gas dissolved in oil = 350 SCF/STB at PB

43. Example: Oil Viscosity
bubble-point pressure PB = 1851 psia
reservoir temperature = 220˚F
oil gravity = 35˚API
gas gravity = 0.68
gas dissolved in oil = 350 SCF/STB at PB

44. GUIDELINES FOR PVT DATA
Verify tables cover expected pressure range
Use smooth data curves
Eliminate negative compressibility problems
Extrapolate laboratory curves above original bubble (dew) point

45. FLUID MODELING
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

46. FLUID REPRESENTATION BLACK OIL AND COMPOSITIONAL
Phase
Gas
Oil
Water
Black Oil
Compositional
Gas C1
Oil C2 C3
C4+

47. PHASES AND COMPONENTS 3 Reservoir Phases 3 Surface Phases
Water
Oil
Surface gas
Gas
Stock tank oil or plant liquids
N Reservoir Components
N Surface Components
C1, C2, … CN
Same as reservoir components
Not necessarily pure species

48. Equations of State Thermodynamic Postulate
All macroscopic properties of PVT systems can be expressed as functions of pressure, temperature and composition only.
EoS concept
One EoS for liquid and vapor
Provides single, consistent source for phase property calculations
Ensures convergence at critical point

49. Equations of State (cont.)
Simplest EoS is Ideal Gas Law:
𝑍= 𝑝𝑉 𝑅𝑇 =1
Van der Waals revised Ideal Gas Law to account for interaction between molecules in non-ideal systems
𝑍= 𝑉 𝑉−𝑏 − 𝑎 𝑅𝑇𝑉

50. 𝑝= 𝑅𝑇 𝑉−𝑏 − 𝑎(𝑇) 𝑉 𝑉+𝑏 +𝑏(𝑉−𝑏)
Examples of Cubic EoS
𝑝= 𝑅𝑇 𝑉−𝑏 − 𝑎/ 𝑇 1/2 𝑉(𝑉+𝑏)
Redlich-Kwong
𝑝= 𝑅𝑇 𝑉−𝑏 − 𝑎(𝑇) 𝑉(𝑉+𝑏)
Soave-Redlich-Kwong
𝑝= 𝑅𝑇 𝑉−𝑏 − 𝑎(𝑇) 𝑉 𝑉+𝑏 +𝑏(𝑉−𝑏)
Peng-Robinson
𝑝= 𝑅𝑇 𝑉−𝑏(𝑇) − 𝑎(𝑇)/ 𝑇 1/2 𝑉[𝑉+𝑏(𝑇)]
Zudkevitch-Joffe

51. Modifying EoS Parameters for Mixtures
Molar Weighted Averages
Binary Interaction Parameters Kij from experimental data on two-component interaction systems.

52. QUESTIONS?
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

53. SUPPLEMENT
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.