Aga8 Versus Gerg2008
Transcript of Aga8 Versus Gerg2008
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Measurement Data: from Well to Awarenesswww.SpiritIT.com
GERG-2008 & AGA-8 UNCERTAINTY
By Han van Dal
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UNCERTAINTY U95%
SYSTEMATIC ERRORS (NOTICED OR UNNOTICED ?)
Hardware failures
Wrong setup / configuration
Faulty data entries
Fixed / frozen input values
Wrong software version
Power resets / reboots
Proving / valve issues
Sampling / lab analysis issues
Failing As-found validations
Calculation failures
...
RANDOM ERRORS
Measurement and analysis reproducibility
Calibration uncertainty
Lab analysis uncertainty
Calculation uncertainty
...
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GAS COMPRESSIBILITY EQUATIONS
Natural gas compressibility = Real gas faktor
= correction on ideal gas law
1873 Van der Waals Equation Of State
1940 Benedict Webb Rubin equation (BWR)
(Soave) Redlich Kwong (SRK)
Lee Kesser (LK)
Peng Robinson (PR)
1962 AGA NX-19
1982 NX-19 PTB G9
1991 S-GERG (AGA-8 Gross Method)
1992 AGA-8 (AGA-8 Detailed Method)
2004 GERG-2004 (later GERG-2008)
Source : COMPRESSIBILITY OF NATURAL GAS - Jeffrey L. Savidge ISHM 2000
Applies for AGA-8 Region 1
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AGA-8 BOUNDARIES
Source: AGA Transmission Measurement Committee Report No.8
NX-19-40..+115C
350 bar
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OVERALL UNCERTAINTY WITH AGA-8 U95%= 0.1%
Source: NFOGM 2003 'Handbook for uncertainty calculations Ultrasonic fiscal gas metering stations'
NORWEGIAN SOCIETY FOR OIL AND GAS MEASUREMENT
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http://www.nfogm.no/http://www.nfogm.no/ -
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OVERALL UNCERTAINTY WITH AGA-8
DETAILED INPUT LEVEL
Relative Relative
Given Relative Confidence Level Type of Standard Sensitivity Relative
Input variables Uncertainty (probability distr.) Uncertainty Uncertainty Coefficient Variance
MODEL UNCERTAINTY1)
Gas compressibility factor at l ine conditions (Z) 0.1 % 95 % (normal) A 0.05000 % 1 0.00000025
Gas compressibility factor at s tandard conditions (Z0) 0.052 % 95 % (normal) A 0.02600 % 1 6.76E-08
ANALYSIS UNCERTAINTY
Line conditions 0.16 % Standard A 0.16000 %
1 0.00000256
Standard conditions 0 % Standard A 0.00000 %
Gas compressibility calculation Sum of relative variances, (EZ0/Z)2
2.8776E-06
Relative Combined Standard Uncertainty, E Z0/Z 0.001696
Relative Expanded Uncertainty (95% c onfidence level, k=2), k EZ0/Z 0.3393 %
1) Re. model uncertainty: AGA-8 uncertainty used for the model uncertainty of Z (line conditions)
ISO 6976 uncertainty used for the model uncertainty of Z0 (standard reference conditions)
Z at line conditions: Fill in AGA-8 uncertainty (option)
Z at std. conditions: Fill in AGA-8 uncertainty (option) Z at std. conditions: Fill in ISO 6976 uncertainty (option)
EMU - USM Fiscal Gas Metering Station
Gas compressibility uncertainty
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0.3
Source: NFOGM 2003 'Handbook for uncertainty calculations Ultrasonic fiscal gas metering stations'
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OVERALL UNCERTAINTY WITH AGA-8 U95%= 0.3%
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Source: NFOGM 2003 'Handbook for uncertainty calculations Ultrasonic fiscal gas metering stations
www.nfogm.no section Handbookshttp://gasmetering.azurewebsites.net
http://www.nfogm.no/http://www.nfogm.no/http://gasmetering.azurewebsites.net/http://gasmetering.azurewebsites.net/http://gasmetering.azurewebsites.net/http://gasmetering.azurewebsites.net/http://www.nfogm.no/ -
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AGA-8 UNCERTAINTY
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Source: AGA Transmission Measurement Committee Report No.8
Uncertainty = ? %
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AGA-8 UNCERTAINTY
Optimized for pipeline quality natural gas in Region 1
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0.2 .. 0.5%
GERG-2008 UNCERTAINTY
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Source: AGA Transmission Measurement Committee Report No.8
0.1%
0.1% -183 .. + 177 C Up to 35 Mpa
0.2 .. 0.5% -213 .. + 427 C Up to 70 Mpa
No limits on composition
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AGA-8 / GERG-2008 : DRY GAS
Methane
83.18
Nitrogen
9.94
Carbon Dioxide
1.79
Ethane
4.05
Propane
0.71
Water 0.00
Hydrogen Sulphide 0.00
Hydrogen
0.00
Carbon Monoxyde 0.00
Oxygen 0.00
i-Butane
0.00
n-Butane
0.23
i-Pentane
0.00
n-Pentane
0.05
n-Hexane
0.05
n-Heptane 0.00
n-Octane
0.00
n-Nonane 0.00
n-Decane 0.00
Helium
0.00
Argon 0.00
NeoPentane 0.00
Sum 100.00
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Relative difference
Z(AGA-8) Z(GERG2008)
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AGA-8 / GERG-2008 : DRY GAS
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AGA-8 / GERG-2008 : SEPARATOR GAS
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Pressure bar(a)
85
Temperature C
24
Total
Liquid
Vapour
C1
mol frac.
0.7302
0.3837
0.8673
C2
0.0786
0.0884
0.0748
C3
0.0431
0.0834
0.0271
nC4
0.0181
0.0472
0.0066
iC4
0.0326
0.0764
0.0153
nC5
0.0117
0.0360
0.0021
iC5
0.0166
0.0470
0.0045
nC6
0.0106
0.0353
0.0009
nC7
0.0209
0.0713
0.0009
nC8
0.0161
0.0559
0.0003
nC9
0.0118
0.0412
0.0001
nC10
0.0097
0.0342
0.0000
Fraction
mol frac.
1.0000
0.2835
0.7165
Fraction
mass frac.
1.0000
0.5174
0.4826
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AGA-8 / GERG-2008 : SEPARATOR GAS
Methane
83.18
Nitrogen
9.94
Carbon Dioxide
1.79
Ethane
4.05
Propane
0.71
Water
0.00
Hydrogen Sulphide 0.00
Hydrogen 0.00
Carbon Monoxyde
0.00
Oxygen 0.00
i-Butane
0.00
n-Butane
0.23i-Pentane
0.00
n-Pentane
0.05
n-Hexane
0.05
n-Heptane 0.00
n-Octane 0.00
n-Nonane
0.00
n-Decane
0.00
Helium 0.00
Argon
0.00
NeoPentane 0.00
Sum 100.00
Relative difference
Z(AGA-8) Z(GERG2008)
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AGA-8 / GERG-2008 : SEPARATOR GAS
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AGA-8 / GERG-2008 : SEPARATOR GAS
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AGA-8 / GERG-2008 : WITH WATER
Methane
82.6
Nitrogen
0.32
Carbon Dioxide
2.01
Ethane
7.41
Propane
4.37
Water
0.5
Hydrogen Sulphide
0
Hydrogen
0
Carbon Monoxyde
0
Oxygen
0
i-Butane
0.83
n-Butane
1.07
i-Pentane
0.31
n-Pentane
0.25
n-Hexane
0.3
n-Heptane
0
n-Octane
0
n-Nonane
0
n-Decane
0
Helium
0.03
Argon
0
NeoPentane
0
Sum
100.00
Relative difference
Z(AGA-8) Z(GERG2008)
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AGA-8 / GERG-2008 : WITH WATER
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AGA-8 / GERG-2008 : WITH WATER
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CONCLUSIONS
AGA-8 IS ACCURATE FOR DRY GAS
as accurate as GERG-2008
also accurate in expanded range
AGA-8 IS LESS SUITED FOR WET GAS
(BOTH HC AND H2O)
calculation failures
increased uncertainty
GERG-2008 IS ACCURATE AND ROBUST
0.1% for both dry and wet gases
no limitation on composition
no calculation failures
10 x CPU time of AGA-8
GERG2008 ALSO FOR LIQUID ?!
liquid density U95= 0.1 .. 0.5 %
online comparison with Coriolis density to
verify well composition ?!
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Measurement Data: from Well to Awarenesswww.SpiritIT.com
THANK YOU FOR YOUR ATTENTION
Questions?