Non-Intrusive Ultrasonic Gas Flow Meter Testing · Non-Intrusive Ultrasonic Gas Flow Meter Testing...

Non-Intrusive Ultrasonic Gas Flow Meter Testing

• Michael Romer, ExxonMobil Upstream Research Company

• Tony Hord and Mike Johnson, ExxonMobil Production Company

• Izzy Rivera and Mike Kuvent, Flexim Americas Corporation

• Ron McCarthy and Bill Vaughan, Siemens Industry, Inc.

• Edward Beeloo and Craig Watterson, Expro Meters, Inc.

• Terry Grimley and Michael Robertson, Southwest Research Institute

Feb. 3 - 7, 2014 2014 Gas-Lift Workshop 1

37th Gas-Lift Workshop Houston, Texas, USA February 3 – 7, 2014

Outline

• Introduction

• Background

• Metering Technologies

• Flow Loop Facility

• Equipment Setup

• Results

• Challenges/Positives

• Conclusions and Future Plans


Introduction

• Does your asset have gas-lift (GL) gas metering?

– Can you measure injection for individual wells?

– Are the meters calibrated on schedule and correctly?

– Do you trust your metering system?

• What could you do if you were able to reliably meter

GL injection rates on each well?

– Individual well injection optimization

– Field-wide injection gas allocation & optimization

– Troubleshooting


Background

• In 2011, ExxonMobil piloted an ultrasonic (UT), clamp-on gas flow meter for measurement of injection gas

• Southwest Research flow loop and field testing showed potential for GL applications

• This spurred interest in other UT gas metering technologies

• A follow-up testing program was initiated in 2013 to validate other commercial UT meters for GL gas injection

• Priorities for metering solutions

– Non-intrusive

– Applicable to GL injection lines

– Portable if possible

– Relatively accurate (within 10%)


Metering Tech. – Meters F and S

• Transit-time principle

– Signal in the direction of flow travels faster than the signal against the flow direction

– The difference in transit time is a measure of the flow velocity

– Challenge: Diesel’s acoustic impedance is 372 times methane’s at 68°F, 150psi; methane’s received signal is .26% of diesel’s


Transit Time Difference, Δt Path of Ultrasonic Signal

© Copyright Flexim 2012 © Copyright Flexim 2012


• Challenges of small diameter, thick pipe

– Low acoustic impedance means lower signal-noise ratio

– Noise signal = pipe wall signal from transmit receiver

– Thicker pipe has more noise; noise can arrive closer in time to measurement signal by going around small pipe

• Dampening materials help reduce noise




• Transducer types

– Lamb Wave

• Frequency matched to the pipe wall thickness to

resonate the wall and create a wide beam

• Increase efficiency of sound transmission in gas

– Shear Wave

• Not matched to pipe wall; less uncertainty of sound

propagation time in the wall

• Single transducer can operate over wider range of

pipe sizes



Lamb Wave principle

Pipe wall resonance

Metering Tech. – Meter E

• Sonar array processing for volumetric flow

– Directly measures velocity of coherent vortical

structures

• Vortical structures – turbulence of pipe wall shearing

• Coherent – maintain shape for 20-40 pipe diameters

• Direct – Gas composition is not required for

measurement – independent of acoustic impedance

– Independent of process pressure and pipe schedule

– Passive, strain-based and active, pulsed-array sonar

tools available

• Active sonar used in these tests



U/l3

1/l3

l2 U/l2

l3 U/l3

1/l1

U/l1

1/l2

U/l2

Wave Number

Fre

qu

ency

Temporal / Spatial Decomposition K-w plot

l1 U/l1

Frequency

Each spatial wavelength has a discrete temporal frequency ( f= U/ l )

Slope of Ridge Determines Flow Velocity




Passive, Strain-Based Sonar Active, Pulsed-Array Sonar

Sonar Algorithms Identify Ridge

Slope yields flow rate

6 inch Sonar Meter Perfromance

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35

Reference Velocity, fps

Measu

red

Velo

city, f

ps

Slope of Ridge Determines Flow rate

Slope of

Convective Ridge:

27 fps

Slope of

Convective Ridge:

5 fps

Slope of

Convective Ridge:

17 fps

6 inch Sonar Meter Perfromance

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35

Reference Velocity, fps

Measu

red

Velo

city, f

ps

Slope of Ridge Determines Flow rate

Slope of

Convective Ridge:

27 fps

Slope of

Convective Ridge:

27 fps

Slope of

Convective Ridge:

5 fps

Slope of

Convective Ridge:

5 fps

Slope of

Convective Ridge:

17 fps

Slope of

Convective Ridge:

17 fps

Slope of

Convective Ridge:

17 fps

Parameter Value(s) EM Test Value(s) Controllability Accuracy

170 MMscfd 0.4 - 4.3 MMscfd

1380 Acfm 6.3 - 43.8 Acfm

Pressure Range 165 - 1100 psig 600 - 1000 psig 1.0 psi 0.015% of value

Pipe Diameter Range 2 - 20 in. 3/4 - 2 in. - -

MRF HPL Operational Capabilities

Maximum Flow Rate 1.0 % of rate 0.1 - 0.25 % of rate

Flow Loop Facility

• Testing was performed at the Southwest Research Institute Metering Research Facility (MRF) High Pressure Loop (HPL)

– The HPL is a closed, recirculating flow loop; discrete gas rates are provided by a combination of critical flow nozzles and pressure is changed by adding/removing gas from the flow loop

– Meters being tested are benchmarked against calibrated critical flow nozzles; test data is recorded and can be analyzed on-line

– Sales-quality natural gas was used for the tests

• Flowmeter test was a low-rate, high-pressure HPL application


Flow Loop Facility – Test Matrix


Schedule

ID (in.)

Wall (in.) 600 1000

L5 6.3 370 615

L10 12.5 735 1225

L5+L10 18.8 1105 1840

L20 25.0 1470 2450

L5+L10+L20 43.8 2575 4290

Nozzle Acfm Velocity (ft/s) Mscfd

36 47

104

20 27 34 43 83 115 139

15 20 26 32 63 86

35

10 13 17 21 42 58 69

5 7 9 11 21 29

Pressure (psi)

0.218 0.344 0.200 0.281 0.179 0.250 0.154

80S

1.939 1.689 1.5 1.338 0.957 0.815 0.742

2 in. 1-1/2 in. 1-in. 3/4 in.

80 160 80 160 80 160Schedule

ID (in.)

Wall (in.) 600 1000

L5 6.3 370 615

L10 12.5 735 1225

L5+L10 18.8 1105 1840

L20 25.0 1470 2450

L5+L10+L20 43.8 2575 4290

Nozzle Acfm Velocity (ft/s) Mscfd

36 47

104

20 27 34 43 83 115 139

15 20 26 32 63 86

35

10 13 17 21 42 58 69

5 7 9 11 21 29

Pressure (psi)

0.218 0.344 0.200 0.281 0.179 0.250 0.154

80S

1.939 1.689 1.5 1.338 0.957 0.815 0.742

80 160 80 160 80 160

2-in. 1-1/2 in. 1 in. 3/4 in.

• Although wall thicknesses within

range for Lamb transducers,

corresponding pipe ID

recommendations were not

• Minimum pressure requirement

of ~150psi met for transducers

Accuracy

Meter Min. Max. (%)* Min. Max.

F 115 1-3 0.020 0.910

S 100 1-2 0.080 1.250

E 10 90 2

Calibrated

Velocity (ft/s) Wall Thickness (in.)

Lamb Transducer

* - Calibrated accuracies not expected for

measurements outside of calibrated conditions

Equipment Setup

• Two 15-ft spools of different pipe sizes were

tested simultaneously

– Larger ID pipe positioned upstream to limit

pressure loss and turbulence downstream

• Meters installed side-by-side on each spool

– Still allowed > 10ODs of space between meters

• All meters tested simultaneously

– Waveforms checked to ensure crosstalk not an

issue; cycled operational meter to verify

• Pressures and flow rates were iterated

– Temp. and pressure recorded near the spools


Equipment Setup – All Meters

Meter F Meter E Meter S

2 in. S80


• Portable or

Permanent

• ½ in. pipe and up

• Permanent or

Test Service

• 2 in. pipe and up

• Transportable or

Permanent

• ½ in. pipe and up (application dependent)

Equipment Setup – Meter F


1.5 in. S80

1.5 in. S160

1.5 in. S80

Acoustic Couplant

Dampening Material

Meter

Transducers

Equipment Setup – Meter S


1 in. S160

Meter

Transducers

.75 in. S80S

2 in. S80

Dampening Material

Equipment Setup – Meter E


Dampening Material

Sensor Head

Transmitter

Slope Determination

2 in. S80

Pipe (in.) Sched 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

80

160

80

160

80

160

0.75 80S

2

1.5

1

Velocity (ft/s)

Results – Meter F


600 psi 1000 psi Error: 0-4% 4-8% 8-12% No Measurement

Outside Meter’s Spec

Pipe (in.) Sched 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

80

160

80

160

80

160

0.75 80S

2

1.5

1

Velocity (ft/s)

Results – Meter S



Pipe (in.) Sched 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

80

160

80

160

80

160

0.75 80S

2

1.5

1

Velocity (ft/s)

Results – Meter E



Signal Quality Challenges

• Preparation of measurement location and installation of

components are key to success

– Smoothing, dampening material, and acoustic couplant

– Pipe ID quality will also affect accuracy

• In some applications it can be difficult to capture a quality signal

– Multiple hardware/electronic options available for finding a solution (particularly

with transit-time technologies); experience will guide usage


.75

in

. S

80S

2 in

. S

160

2 in

. S

80

Data Analysis Positives


• “All-or-Nothing” Data Collection

– If adequate signal quality cannot be achieved, you will not get data

• Transducer Spacing Forgiveness

– Able to experiment with transducer locations to optimize signal strength before securing both in place

– Actual spacing then input in meter

• Logging Capability

– Metered data can be exported to spreadsheet format and edited

– Initial input parameters can be determined and modified if necessary

Conclusions and Future Plans


• Non-intrusive UT technologies were successfully applied to GL gas measurement at the MRF

– Challenging pipe sizes/conditions and pressures

– All meters able to measure flow on all pipe sizes

– Better than 10% accuracy

• Training & experience are key components to measurement success

• Future Plans

– Continue and expand testing during GL optimization visits

– Incorporate with other GL diagnostic methods

– Investigate permanent technologies for expansion or retrofitting of GL metering

Questions?


37th Gas-Lift Workshop Houston, Texas, USA February 3 – 7, 2014


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