IFFS AUG2009 Lawrence-Davis

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Field Application ComparisonConditioning Type Orifice Plates (4-holed) and Generic Cone Meters

Mark W. Davis, Senior Staff EngineerShell Exploration & Production Co. Inc.

Houston, Texas USA

Philip A. Lawrence, Director of Business DevelopmentCameron Measurement Systems, Inc.

Houston, Texas USA



Abstract

• Allocation measurement of produced hydrocarbon gas inthe upstream area require different measurementtechniques and strategies than those used for standardpipeline quality gas measurement

• Wet Gas, Hydrate Formation, Liquid Slugging, well clean-up debris and short meter runs all add to the difficult task ofcollecting meaningful data from High Pressure Full Well

Stream (HPFWS) allocation metering points.

• Various meter types have been employed for these flowregimes in order to meet the necessary accuracy

requirements and the arduous duty

• This paper details the real world experience of such aallocation metering system operating in Wyoming, USA.



Field Location• The location of the subject field is in West Central

Wyoming consisting of remote well pad locations where

access can pose problems during the winter months dueto various environmental factors such as weather andanimal migrations.

• From a sustainability standpoint, the remotemeasurement systems must operate effectively withminimum maintenance during these months with limitedaccess

• The measurement systems installed at the locationsshown use full well-stream metering and are adjusted byusing a well test separator to calculate the volumecorrection factor for the wet gas metering.



Field Location

PINEDALE WYPINEDALE WY



Field Location

The environmental issue is one of keeping the productionfacilities to the smallest footprint possible, due to the impacton the local wildlife particularly the mule deer which use the

Pinedale Anticline as a migratory route



Measurement Philosophy

• Metering is required to fulfill a number of functions drivenby regulatory, industry and internal requirements.

• The metering function relates to process control, salesquantity and quality, and hydrocarbon accounting.

• To simplify facilities, metering equipment is minimized tothat deemed necessary to run the business.

• Metering devices, flow conditioning equipment andancillaries are designed to meet the necessary level of

accuracy only. (Fit for purpose).

• To BLM Local Oil and Gas Conservation Commissionregulations, API standards, Sarbanes–Oxley (Sox)

compliance, and reservoir management requirements.




• Continuous readings are taken during the well testingprocess.

• The test separator gas volumes are compared to the(HPFWS) Differential Pressure Meters (e.g. Cone Meter,Conditioning Orifice Plate, or similar devices) readings.

• From this data gas volume correction factors calculated.

• Once the gas volume correction factor (GVCF) is obtained,the gas only volumes from the HPFWS Meter is used tocalculate liquid volumes




• The well test is used to calculate a daily well theoreticalcontribution percentage for oil, water, and gas. Thispercentage is calculated using algorithms involving thedaily readings from the HPFWS Meter and the well testfactors.

• The daily sales are then allocated to each well based oneach wells calculated contribution percentage. The fiscalallocation occurs when the daily sales readings are

replaced with final sales readings and the same dailytheoretical contribution percentage is applied.



Meter Types and Usage

• The use of Differential Pressure Technology (D.P.) tomeasure the full well stream wet gas was favoredbecause these types of devices appeared to be less

susceptible to the effects caused by the multiphaseaspects of the fluid and correction can be done from thewell test data.

• Since a correction factor / allocation factor is calculatedfor each well location the most important requirementsare that the full well stream meter is robust, has a

predictable and repeatable operating envelope, and isrepresentative between well tests. (Usually 24 hrs 1 xper month to develop the GVCF)



Well Test Manifold System

• A well test manifold is installed in the flow linedownstream of the HPFWS meters. There are chokessituated upstream of the HPFWS meters on most of the

locations.

• Samples are taken at least semi-annually from each gas

and condensate stream.

• Shrinkage factors are applied to the gross volume

obtained by the well test separator condensate/oilturbine meters to determine the net stock tankcondensate volumes.



Lease - level Points of Measurement.

M

M

M

M

Well TestSeparator

BulkSeparation

M

M

M

M

LiquidsGathering &

StabilizationSystem

M

M

To Gas Gathering System.

Condensate to Sales Export.

Water to Disposal and/ or

Water Recycling.

Field - wide Allocation Meters.

Flash Gas.

Cone Meter.

Orifice Plate.

Turbine Meter.

Turbine Meter.

Orifice Plate. Orifice Plate. Custody Meter.

Turbine Meter.

Individual Well Measurements.

Turbine Meter.

Turbine Meter.

Full Wellstream .

Gas.

Condensate.

Water.

Gas.

Condensate.

Water.

Cone Meter

Cone Meter

DP Cone Meter 2nd

Well Head AllocationTypical System

4 holed plate 1st



Meter Correction Calculations.

• During well testing the volume of gas is measured at theoutlet of the test vessel and recorded as the Standard

Gas Volume (SGV).

• Indicated Full Well Stream Volume FWSV is alsorecorded during the same time frame.

• The SGV divided by the FWSV yields a gas volumecorrection factor (GVCF) that is used to ascertain the

gas volumes through the HPFWS Meter



Gas Meter Correction Calculations.

Thus;

• FWSMF = SGTV / GVCF

Where; • SGTV = Standard Gas Test Volume (MCF).

• GVCF = Full Well Stream Standard Volume

• FWSMF = Full Well Stream Meter Factor.



Condensate Volume Calculations.

• Volumes of produced Condensate during the well test arealso recorded.

• The indicated “gross” volumes usually are corrected tostandard conditions (net volumes) in accordance with APIMPMS 20.1.latest revision.

• The net volume is used as well as the gas volumes fromprevious in ascertaining the barrels of condensate per

million cubic feet of gas yield (Bbl/MMCF).



Condensate Volume Calculations.

Thus;

• CBMCF = CTV / (SGTV / 1000)

Where; • CBMCF = Condensate Barrels per MMCF.

CTV = Condensate Test Volume.Water Volume Calculations.•Produced water volumes are ascertained in the same

manner as the condensate volumes since water at ambienttemperature is assumed to be non-compressible.

•The only difference is that there is no correction from gross

to net volumes during the well test period required.



Full Well Stream Meter (A) 4-Holed

Differential Orifice Plate Devices.

• Originally full well stream meters where selected on a

cost basis and 4-holed orifice devices were used.

• 250 devices were originally used at the Pinedalelocations and field data for these devices was collected

over an 18 month period.

• It was discovered over this period that various

operational issues occurred resulting in less thansatisfactory measurement results causing the operator tore-think the measurement



Full Well Stream Meter (A) 4-Holed

Differential Orifice Plate Devices.• Typically a circular plate is cut from stainless or other

materials and 4 circular holes equally spaced on a radius

are machined with a typical equivalent area ratio of astandard orifice plate to satisfy the normalized flow ratesper diameter

4-Holed Differential Orifice Plate Device Types



4-Holed Orifice Plate Devices.

• Beta RatioThe effective area ratio for all differential

pressure devices is a function of the restrictionversus the pipe area, the manufacturer’spublished data sheet table for the four holedplate meter shows the beta ratio calculation for

the device. 4 Holed Orifice Plate (β) Equation

Where d = Hole size of each of the holes

Where Pid = Pipe Internal Diameter

o.p.




Beta Ratio Chart

3 inch diameter meter tubes selected from suppliers calculationsANSI class 2500 # N.B. beta changes as pipe schedule is changed




Published Data to API 22.2 Test Protocol(Hollister & Dyer 2008 NEL-TUV O&G Production Conference Houston)

Baseline and Disturbance Testing

4 inch device ½ moon plate + baseline



Full Well Stream Meter (B) - Generic

Differential Pressure Cone Meter• All Cone Meters (non-wall tap design) consist of a conically shaped

differential pressure producer fixed concentrically in the center of a

pressure retaining pipe using a cantilever member, by which adifferential pressure can be obtained across the interface of twocone frustums via an internal portway system.

Computational Fluid Dynamics Image (50% ‐ Section)

Meter Throat

FLOW

P2

Meter Tube Wall

Figure 9 (CFD)

P1P2

Separation



Side View Showing Velocity Vectors and

Downstream Wake Cone Meter



Full Well Stream Meter (B) - Generic

Differential Pressure Cone Meter

Field Acceptance

• The concept of using the rear center of the cone tomonitor the downstream pressure has showncertain benefits

• Flow Conditioning Effect. (shorter runs)

• High Turndown Ratio. ( up to 10-1 )

• Some Static Mixing.

• Wet Gas usage at Lockhart & Martinelli Wet Gas TestValues LM = up to 0.35 & LM = 0.5. (One test Lawrence-Stevens - NSFMW 2003)

• Low Maintenance Application: Design is Robust.



Fluid Velocity Vector Interaction

Fluid Linearization and Interaction in the Meter Throat

Keeps the Throat of the Meter Clean by Sweeping Action

Fluid Flow Common - Velocity



Beta Ratio Cone Meter

• Cone meter area b ratio’s are varied to accommodate

the measurement of different flow rates by changing thecone length and thus the cone diameter.

• This changes the effective diameter of the cone inrelation to the pipe diameter (D) and thus the beta ratio.

2 2( )d D D β = − ∗

2 2 D d

D β −

=

Generic Cone Meter b Equations



Beta Ratio Cone Meter

Beta edge boundary

Taps: Static Low Pressure ΔP

Figure 13



Cone Meter Design

Smooth Flow Entry With No Weld Bead (prevents jetting)

Improvement by someImprovement by somemanufacturersmanufacturers



Cone Meter Design

Flow Conditioning Effect (Cone Meters)

• It is known from research that the use of a cone shapeconcentrically mounted in a closed conduit (pipe) can

facilitate a flow conditioning effect by “velocity profile re-distribution”.

•This effect seems to occur over quite a wide ReynoldsNumber (ReD) range and appears to be enhanced fartheraway from the transition region and also as a function of betaratio.



Cone Meter Design

API Chapter 22.2 Testing of Generic Cone Meters

• Various generic cone meters supplied by CameronMeasurement Systems were tested at the ColoradoEngineering Experimental Engineering Station (CEESI)facility in Nunn recently for the API chapter 22.2 test

protocol requirements.

• Test results for a 2 inch 0.45 beta meter which involved afull suite of disturbance testing is shown next.

•The test is extreemly aggressive incorporating ½ moonplate testing , O.P. elbow test , swirl generator test.



Cone Meter Design

API Ch-22.2 Testing of Generic Cone Meters (CEESI)(Air @ 165 psi ambient temp 2 inch 0.45 beta ratio)

+/- ½%

0.870

0.875

0.880

0.865

0.860

0.855

0.850

0.885

0.890

baseline



Installation Cone Meters

Process Conditions and Operating Criteria

• a) Initial Condition : 10 MMcf/day @2000 psig density 0.0443 lbm//ft^3

• b) Majority Condition : 6 MMcf/day @

600 psig density 0.0443 lbm//ft^3

• c) End Life (new) : 1.5 MMcf/day @

600 psig density 0.0443 lbm//ft^3

• d) Old End life data : 1.0 MMcf/day @600 psig density 0.0443 lbm//ft^3



Installation Cone Meters



Field Allocation Results

• Example (A) Four Holed Orifice Plate

• Average Daily Rate = 3,757-MSCF/day.

Cut Off

0.00%

- 6.00%



Field Allocation Results

Example (B) Generic Differential Pressure Cone MeterAverage Daily Rate = 1461.5-MSCF/day

-3.00%

0.00%

outlier

-2.00%

+1.00%



Conclusion• Both the 4-holed orifice plate and cone metering

technologies provided wet gas measurementaccuracy for well level allocation when adjusted bythe “GVCF” method.

• The Generic Cone metering technology waschosen by Shell E&P because of enhanced

operational and in-field documented allocationaccuracy, with more robust wear capabilities inthis particular flow regime.

• Reduced meter inspection frequencies and lessproblem interventions were also observed with thistype of device.

IFFS AUG2009 Lawrence-Davis

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