1. Natural Gas Processing

2. If this guy can understand gas plant accounting, so can you…

3. Natural Gas
Composition and Properties

4. Composition Well Stream Raw Gas Inert Gases Water Condensate
Contaminant
Gases
Hydrocarbons

5. Hydrocarbons H 1 C 6
Hydrogen
1.0079
Carbon

6. Hydrocarbons
Hydrogen
Carbon
Chemical Bond

7. Hydrocarbons
Methane

8. Hydrocarbons
Methane
Ethane

9. Hydrocarbons
Methane
Ethane

10. Hydrocarbons
Methane
Ethane
Propane

11. Hydrocarbons
Methane
Ethane
Propane
Iso Butane

12. Hydrocarbons
Methane
Ethane
Propane
Iso Butane
Normal Butane

13. Hydrocarbons Methane Ethane Propane Iso Butane Normal Butane
Iso Pentane
Normal Pentane
Neo Pentane

14. Hydrocarbons Residue Gas* Natural Gas Liquids (NGL) Methane Ethane
Propane
Iso Butane
Normal Butane
Iso Pentane
Normal Pentane
Neo Pentane
* Methane is the primary component.
May contain some ethane, propane, etc.
Hexanes Plus

15. Physical Properties Units of Measurement Volume (Gallons) Energy
(MMBtu)
Volume
(Mcf)

16. Physical Properties Conversions Convert between pressure bases
Uses ratios of pressures
Convert between units of measurement
Uses factors (Btu factor, Shrink factor, GPM)

17. Physical Properties Pressure Bases 14.65 psi 14.696 psi 14.73 psi
Atmospheric Pressure
psi
14.73 psi
psi

18. Physical Properties Conversion Factors Btu Factor:
Mcf x Btu Factor = MMBtu
Gas Quantity Lost Due to
Extraction of a Particular
NGL Component
Shrink Factor:
Gallons x Mcf Shrink Factor = Shrink Mcf
Gallons x MMBtu Shrink Factor = Shrink MMBtu
GPM Factor:
Mcf x GPM Factor = Component Gallons
Theoretical Gallons of
Particular NGL Component
Contained in Gas

19. Physical Properties Converting volumes between pressure bases Volume
PB1
Volume
PB2
PB1 x =
PB2

20. Physical Properties Converting volumes between pressure bases Ex.
14.65
Psi x =
Psi
14.73

21. Physical Properties Converting volumes between pressure bases Ex.
14.73
Psi x =
Psi
14.65

22. Physical Properties Converting volumes to energy x Btu Factor @ P.B 1=
Volume
(Mcf)
Energy
(MMBtu)
@ P.B. 1

23. Physical Properties Summary of Conversions Between Pressure Bases
P.B. 1
P.B. 1 x =
P.B. 2
P.B. 2
P.B. 2
Btu P.B. 1 x =
Btu P.B. 2
P.B. 1
P.B. 1
Mcf Shrink P.B. 1 x =
Mcf Shrink P.B. 2
P.B. 2
P.B. 2
P.B. 1 x =
GPM P.B. 2
P.B. 1

24. Physical Properties
Summary of Conversions Between Units of Measurement
P.B. 1 x
Btu P.B. 1 =
MMBtu
P.B. 1 x
P.B. 1 =
Gallons
Gallons x
Mcf Shrink P.B. 1 =
P.B. 1
Gallons x
MMBtu Shrink Factor =
MMBtu

25. Physical Properties Tips for Conversions High Pressure to Low Pressure
=> Volume Increases
Low Pressure to High Pressure
=> Volume Decreases

26. Physical Properties Tips for Conversions High Pressure to Low Pressure
=> Btu Factor, GPM, Mcf-Shrink Factor Decreases
Low Pressure to High Pressure
=> Btu Factor, GPM, Mcf-Shrink Factor Increases

27. Field Operations
From Well to Inlet

28. Metering
Gas Meter
P1, T1
P2, T2
Orifice Place

29. Separation
Gas
Oil
Water
Coalescing Plates
Deflector Plate

30. Gathering Lines
& Pigging

31. Gathering Lines & Pigging Physical Barrier between liquid and gas
Check pipe integrity and remove debris
Provide known volume for meter calibration
Coat inner pipe with corrosion inhibitors
Remove condensed water any hydrocarbon liquids

32. Compression
Due to the complexity of a compressor animation and the limitations of PowerPoint, I was unable to create a sufficient animation for compression.

33. Compression
So here’s an animation of some baby chickens:

34. Compression
Wait, here’s an animation from MAN Diesel and Turbo:

35. Compression Oil-free Rotary Screw Compressor Centrifugal Compressor
Pictures from Fundamentals of Natural Gas Processing 2nd ed., Kidnay 2006

36. Gas Processing
From Inlet to Tailgate

37. Gas Flow Gas From Field Raw Helium Sales Gas Inlet Receiving Water &
Solids
Nitrogen
Rejection
Helium
Recovery
Outlet
Compression
Inlet Compression
Hydrocarbon
Recovery
Gas Treating
Dehydration
Natural Gasoline
Liquids Processing
NGLs
Based on diagram from Fundamentals of Natural Gas Processing 2nd ed., Kidnay 2006

38. Components vary based on desired products
Hydrocarbon Recovery
Components vary based on desired products

39. Hydrocarbon Recovery External Refrigeration Turboexpansion
Heat Exchangers
Fractionators

40. Plant Configurations SWEET GAS Sales Gas EPBC CO2 High Pressure Gas
Propane
Refrigeration
Residue
Compression
Sales Gas
Dehydration
EPBC
Hydrocarbon
Recovery
CO2
Amine Treating
Heat Exchange
High
Pressure
Gas
Inlet
Compression
Compression
PBC
Deethanizer
Low
Pressure Gas
Based on diagram from Fundamentals of Natural Gas Processing 2nd ed., Kidnay 2006

41. Accounting
Gas Allocations and Other Principles

42. Allocations
Principles
Design
Execution
Validation

43. Principles
Contractual

44. Reflects Operational Dynamics
Principles
Reflects Operational Dynamics

45. Principles
Equitable

46. Principles
Start with most accurate method, simplify if no material effects and simplification is contractual

47. Designing Allocations
Step 1 – Identify Sources and Dispositions
Step 2 – Determine Allocation Order
Step 3 – Determine Allocation Pools
Step 4 – Determine Allocation Basis

48. Designing Allocations
Step 1 – Identify Sources and Dispositions
Compressor 1
Gas
Plant

49. Designing Allocations
Step 1 – Identify Sources and Dispositions
Compressor Fuel 1
NGLs
Compressor 1 2
Gas
Plant 3
Residue Gas
Plant Fuel 4 5 6

50. Designing Allocations
Step 1 – Identify Sources and Dispositions
Compressor Fuel 1
NGLs
Compressor 1 2
Gas
Plant 3
Residue Gas
Plant Fuel 4 5 6

51. Designing Allocations
Step 1 – Identify Sources and Dispositions
Compressor Fuel 1
NGLs
Compressor 1 2
Gas
Plant 3
Residue Gas
Plant Fuel 4 5 6

52. Designing Allocations
Step 1 – Identify Sources and Dispositions
Sources
Dispositions
Compressor Fuel 2 4 1
Residue Gas
NGLs 5 3 6
Plant Fuel

53. Designing Allocations
Step 2 – Determine Allocation Order
The further upstream a disposition, the sooner it is allocated
The further downstream a disposition, the later it is allocated

54. Designing Allocations
Dispositions
Designing Allocations
Compressor Fuel
Step 2 – Determine Allocation Order
Residue Gas
NGLs
Plant Fuel

55. Designing Allocations
Dispositions
Designing Allocations
Step 2 – Determine Allocation Order
Residue Gas
NGLs
Plant Fuel 1
Compressor Fuel

56. Designing Allocations
Dispositions
Designing Allocations
Step 2 – Determine Allocation Order
Residue Gas
Plant Fuel 1
Compressor Fuel 2
NGLs

57. Designing Allocations
Dispositions
Designing Allocations
Step 2 – Determine Allocation Order
Residue Gas 1
Compressor Fuel 2
NGLs 3
Plant Fuel

58. Designing Allocations
Dispositions
Designing Allocations
Step 2 – Determine Allocation Order 1
Compressor Fuel 2
NGLs 3
Plant Fuel 4
Residue Gas

59. Designing Allocations
Compressor Fuel 1
Step 3 – Determine Allocation Pools 1 2 3
NGLs 2 4 5 6 1 2 3
Plant Fuel 3 4 5 6 1 2 3
Residue Gas 4 4 5 6 1 2 3

60. Designing Allocations
Step 4 – Determine Allocation Basis
Is Gas Used? What determines usage?
Is Gas Extracted, changes state (i.e. gas to liquid)?
Unit of Measurement?

61. Executing Allocations
Starting with disposition 1
For each source in the allocation pool, compute theoretical volume:
Source – Sum(Dispositions) = Theoretical
Compute Total Theoretical
For each source, computed allocated share:
Source Theoretical
X Disposition = Allocated Share
Total Theoretical

62. Allocations Allocating NGLs is normally 2-step computation:
- Compute each source’s Mcf of inlet gas
Apply Component GPM to Mcf => Theoretical Component Gallons

63. Allocations Least Accurate to Most Accurate NGL Allocation: Mcf MMBtu
Total GPM => Total Theoretical Gallons
Component GPM => Theoretical Component Gallons

64. Verifying Allocations
Balance the System
Balance each Well

65. Verifying Allocations
Balance the System
Total Sources – Total Dispositions
>>>> 0 (0%)
Missing Disposition
Bad (low) Disposition Measurement
Significant, actual loss
Bad (high) Source Measurement

66. Verifying Allocations
Balance the System
Total Sources – Total Dispositions
<<<< 0 (0%)
Missing Source
Bad (high) Disposition Measurement
Bad (low) Source Measurement

67. Verifying Allocations
Balance Wells
Apply Same Formula for System Balance on a well-by-well basis
Cumulative, common differences among groups of wells can imply:
Allocation did not reflect operational dynamics
Wrong allocation basis chosen for one or more dispositions

68. This allocation process applies to all gas allocations, regardless processing

69. Documents
Settlement Statements and Measurement Data

70. Heating Value (Btu/Scf
Gas Volume Statement
March 2014
Meter No
212354
Name
ExtraSpecial Well
Pressure Base
14.73
Temperature Base 60
Day
Differential (in. H2O)
Pressure (psia)
Temperature (F)
Flow Time (hrs)
Relative Density
Plate (inches)
Volume (Mcf)
Heating Value (Btu/Scf
Energy (MMBtu) 1
2.13
143.01
94.35
20.62
0.8155
0.3750
10.59
14.8 2
2.18
143.06
93.25
20.65
10.72
14.97 3
2.43
141.67
92.95
19.63
10.33
14.43 4
2.15
141.80
92.27
18.73
9.31
13.01 5
7.79
141.04
91.74
14.32
10.36
14.48 6
10.55
140.96
89.27
11.29
10.53
14.71 7
10.52
141.18
91.73
11.43
10.63
14.85 8
9.63
141.41
89.15
12.12
10.81 9
10.07
141.39
91.76
11.15
9.96
13.92 10
8.00
133.50
88.73
3.29
2.35 11
0.00
60.40
98.14 12
64.75
81.40
112.18
0.28
0.34
0.47 13
1.43
143.74
82.94
2.46
0.91
1.27 14
2.74
131.38
96.14
11.65
4.96
6.94 15
2.56
132.27
92.72
16.22
8.30
11.59 16
4.14
143.99
92.97
13.46
9.07
12.67 17
7.03
144.03
87.06
18.42
14.99
20.94 18
6.42
143.82
87.68
16.85
12.69
17.73 19
15.96
143.95
79.27
23.26
32.65
45.62 20
16.49
143.89
87.64
23.56
33.95
47.43 21
60.79
143.28
87.52
23.93
40.68
56.83 22
40.10
117.69
78.31
4.59
6.13
8.56 23
132.44
142.99
85.37
8.67
28.73
40.14 24
3.67
145.06
116.50
0.66
0.39
0.54 25
210.52
144.93
101.45
2.25
9.75
13.62 26
2.08
144.99
104.40
1.09
0.48
0.67 27
4.81
144.87
102.22
4.64
2.76
3.86 28
1.41
145.26
98.68
3.39
1.40
1.95 29
1.68
145.14
103.88
3.64
1.62
2.26 30
34.12
144.64
88.19
3.55
0.8155·
2.05
2.87
Total
34.64
141.96
88.80
325.79
307.42
429.51
Meter Statement
Meter/Operator
Information
Measurement Conditions,
Methods, Basis
Daily Volume and Energy Data

71. Gas Analysis Statement
Meter/Operator
Information
General Sample Info
Analysis Data

72. Plant Settlement Statement
Contract/Operator
Information
Gas Computations
NGL Computations

73. Questions?

74. Thanks!
The End!!!!!!