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Well Testing – An Evaluation of Test Separators and Multiphase Flow Metersp
Oil & Gas Focus GroupWednesday 14th September 2011
Amy Ross, NEL
Wednesday 14 September 2011
y ,
Contents
• Why are you well testing?
• Test Separators– Metering
Utili ti– Utilization
• What makes a good well test?
• Multiphase Meters– Performance– Utilization
• Conclusions• Conclusions
Contents
• Why are you well testing?
• Test Separators– Metering
Utili ti– Utilization
• What makes a good well test?
• Multiphase Meters– Performance– Utilization
• Conclusions• Conclusions
Why are you well testing?
• Determination of fluid flow rates
D t i ti f h h i fl id fl• Determination of when changes in fluid flow rates/composition occur
• Identification of mechanical integrity issue• Identification of mechanical integrity issue
• Because the Regulator has told you to...
Contents
• Why are you well testing?
• Test Separators– Metering
Utili ti– Utilization
• What makes a good well test?
• Multiphase Meters– Performance– Utilization
• Conclusions• Conclusions
How do you well test?
gas
oilwater
The gold standard
Works well if...
• Separator is sized correctly
I t f l l it bl i t i d• Interface levels are suitably maintained
• Flow meters are adequately sized
• Flow meters installed in recommended orientation with required upstream and downstream straight lengthsdo s ea s a g e g s
• Flow meters are regularly inspected and calibrated
• Secondary instrumentation are regularly calibrated
Test Separator - Metering
Test Separator - Metering
Test Separator – Other issues
Test Separator – Metering Uncertainties
Gas UncertaintiesB t ±2%• Best ±2%
• More likely ±3% to ±6%• Extreme ±10% to ±15%
Liquid UncertaintiesBest ±1% to ±2%• Best ±1% to ±2%
• More likely ±2% to ±5%• Extreme ±5% to ±10%
Test Separator - Utilization • Regular well testing
• Other well testsOther well tests
• Separator use during well service operations
• Other uses• Other uses
– Start up of low pressure wells after shut down
Test a multiphase flow meter– Test a multiphase flow meter
• Separator maintenance & inspection
PSV’ f t t– PSV’s, safety systems
– Removal of solids
– Instrument calibration
Contents
• Why are you well testing?
• Test Separators– Metering
Utili ti– Utilization
• What makes a good well test?
• Multiphase Meters– Performance– Utilization
• Conclusions• Conclusions
What makes a good well test?
• One which follows the previous well tests, therefore demonstrating repeatabilitydemonstrating repeatability
• One which is within the stipulated period of 30 days
• Identification of mechanical integrity issue• Identification of mechanical integrity issue
• One which has been carried out for the stipulated length of time (12 or 24 hours)o e ( o ou s)
Just ticking the boxes – need to look at the bigger pictureJust ticking the boxes need to look at the bigger picture
GVF > 90%, WC ≈ 60%
Flow Rates
Fluids – Green - Oil,Blue – Water, Yellow - Gas
Flow Rates
5
10
Liqu
id [m
3/h]
Flow Rates
300
400
Gas
[m3/
h]
0 50 100 150 200 2500
0 50 100 150 200 250200
4000
5000Venturi dPVenturi dP
0 50 100 150 200 2500
1000
2000
3000
mB
ar
GVF & WLRGVF and WLR
50
100
[%]
GVF & WLR
WLRGVF
GVF and WLR
0 50 100 150 200 2500
Time [Minutes]
Slugging, WC ≈ 0 to 70%
40Flow Rates
400
Liquids – Green - Oil ,Blue – Water, Yellow - GasFlow Rates
10
20
30
40
Liqu
id [m
3/h]
100
200
300
400
Gas
[m3/
h]
0 20 40 60 80 100 1200
0 20 40 60 80 100 1200
4000
5000Venturi dPVenturi dP
0 20 40 60 80 100 1200
1000
2000
3000
mB
ar
GVF and WLR
50
100
[%]
GVF & WLR
WLRGVF
GVF and WLR
0 20 40 60 80 100 1200
Time [Minutes]
GVF > 90%, WC > 90%
Flow Rates
Liquids – Green - Oil ,Blue – Water, Yellow - GasFlow Rates
10
20
30
40
Liqu
id [m
3/h]
Flow Rates
100
200
300
Gas
[m3/
h]
0 50 100 150 200 250 300 350 400 4500
0 50 100 150 200 250 300 350 400 4500
4000
5000Venturi dPVenturi dP
0 50 100 150 200 250 300 350 400 4500
1000
2000
3000
mB
ar
GVF and WLR
50
100
[%]
GVF & WLR
WLRGVF
GVF and WLR
0 50 100 150 200 250 300 350 400 4500
Time [Minutes]
Contents
• Why are you well testing?
• Test Separators– Metering
Utili ti– Utilization
• What makes a good well test?
• Multiphase Meters– Performance– Utilization
• Conclusions• Conclusions
Multiphase Flow Meters
• Capable of continuous measurementp
• Stabilise their process conditions much more quickly that a test separator
• Key to economic development of smaller, more marginal fields
However....
• Have performance claims been met?
• What steps are necessary to achieve success?
• Successes are aired but what about the failures?
Multiphase Flow Meter Performance
Uncertainties of ±10% to ± 25%
Cut
(%)
(%)
Wat
er C
GVF (%)
Multiphase Flow Meter PerformanceNow....
•Auto-switchable between multiphase and wet gasp g
•Wet gas uncertainties
o Better than ±5% for liquid flow rateo Better than ±5% for liquid flow rate
o ±2% to ±5% for gas flow rate
o Better than ±2% (abs) for water detectiono Better than ±2% (abs) for water detection
•Multiphase uncertainties
o ±2% to ±5% for liquid flow rateo ±2% to ±5% for liquid flow rate
o ±2% to ±5% for gas flow rate
±1% t ±8% f t to ±1% to ±8% for water cut
Multiphase Flow Meter Performance
How have these improvements been achieved?
• Competition between vendors• Open and independent Joint Industry Projectsp p y j• Significant R&D expenditure by vendors, operators,
universities, etc• Innovative alliances by vendors and operators• Innovative alliances by vendors and operators• Users becoming MPFM aware• Improvements in flow models• Improvements in computing power• Some very awkward individuals asking very
awkward questionsawkward questions
Test Separator - Utilization
• Regular well testing
• Other well tests
Could be achieved by MPFM
Could be achieved by MPFMOther well tests
• Separator use during well service operations
• Other uses
Could be achieved by MPFM
• Other uses
– Start up of low pressure wells after shut down
Test a multiphase flow meter– Test a multiphase flow meter
• Separator maintenance & inspection
PSV’ f t t– PSV’s, safety systems
– Removal of solids
– Instrument calibration
Multiphase Flow Meter Utilization
Test Separator
FM gas
Test Manifold 1
FM
FM
oil
waterMultiphase /
Test Manifold 2
1st Stage
gas
waterMultiphase / Wet Gas Meter
1st Stage Separator
oilProduction M if ld waterManifold
From wells
Multiphase Meters
How do you reconcile a multiphase flow meter i t th t t t ?against the test separator?
gas
MPFM
oilwater
MPFM
oilwater
Contents
• Why are you well testing?
• Test Separators– Metering
Utili ti– Utilization
• What makes a good well test?
• Multiphase Meters– Performance– Utilization
• Conclusions• Conclusions
Conclusions
• Well testing must be done
• Test separators are seen as the gold standard
– Often not suitably maintained or operatedy p
– Over utilized
• Multiphase meter technology has improved greatly over u t p ase ete tec o ogy as p o ed g eat y o ethe past 20 years
• Multiphase meter performance will continue to improve IF vendors and operators work together
• Opportunity for multiphase meters to compliment test tseparators
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