wet gas metering by isokinetic sampling

8/10/2019 Wet Gas Metering by Isokinetic Sampling

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Wet Gas Metering by IsokineticSampling

MFIP13 Sestri Levante, Sept. 17-19, 2014


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Wet Gas Metering by Isokinetic Sampling

N. Bonavita, G. Ciarlo, ABBP. AndreussiUniversit di Pisa

P. CiandriTEA Sistemi, PISA

Paper presented by

Presented at:

13th INTERNATIONAL CONFERENCEMULTIPHASE FLOW IN INDUSTRIAL PLANT

Sestri Levante (Genova), ItalySeptember 17-18-19, 2014


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MULTIPHASE FLOW METERING

Starting from 1992 TEASistemi developed MPFMs basedon the use of a gsource coupled with an electricalimpedance meter and a Venturi meter. First commercialMPFM built by TEASistemi was installed in Preziosoplatform (Sicily) in January 1996.

In 1998 TEASistemi launched an internal R&D projectaimed at the development of a Multiphase Flow Meterbased on Isokinetic Sampling: The VEGA meter, initiallydesigned for wet gas applications.

The field tests of this meter were carried out at Trecate

field in 2000-2001. The first commercial intallation of VEGAregarded the Allegheny platform, Gulf of Mexico in 2002(Worlds First Installation of a MWGM).


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MULTIPHASE FLOW METERING

The conventional instrumentation installed in the VEGAmeter was designed and produced by ABB. This led ABBand TEA Sistemi to sign a cooperation agreement which isformally effective from Sept 12, 2014.

According to this agreement, TEA Sistemi will continue theproduction of a new generation Wet Gas meter, the VISmeter, and ABB will contribute to its development and sellthis meter in the international market.

The technical cooperation between TEA Sistemi and ABBis bringing new life into the project and also regards other

applications.The objective of this presentation is to describe the mainfeatures of VEGA and the motivation which led to thedevelopment of VIS.


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VEGA meter

The measuring principle of VEGA is the IsokineticSampling of the gas- liquid mixture. Its present applicationregards high gas volume fractions (GVFs 85-100%).

The measurements performed by the meter are

Differential pressure drop through an orifice;Gas and liquid flowrates of a sample (after phaseseparation)

The accuracy of the meter can be as good as +/- 2.5% ofthe actual liquid and gas flow rates.


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Isokinetic Sampling

Sampling is performed in a section of the pipe where thetwo phases (gas and liquid) are well mixed (velocity profilesare uniform)

The liquid volume fraction in the sample is the same as inthe main stream

Isokinetic sampling requires that the ratio between thesampling flowrate and the overall flowrate be the same asthe ratio between the sampling probe cross section and thepipe cross section (at the sampling location)


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DP>0

DP


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Q1= Q 0

Qs=0

Q0

DP

P 0= Q 02

P 1= Q12= (0.9) 2Q02

1

2

P 1 P 0

=0.81

Q1= 0.9 Q 0

Qs= 0.1 Q 0

Q0

DP

Isokinetic Sampling


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King Kong VEGA (GOM), 2002

Operative Conditions and GeometryPressure 1000-2000 psig

Temperature 40-50 F

Gas Flow 25-100 MMscfd

Liquid Flow

Water 25-100 bbl/d

Methanol 25-100 bbl/d

Condensate 125-800 bbl/d

Gas Superficial Velocity (actual) 7-60 ft/s

Nominal Diameter 8 inDimensions (main vessel)

height 7 ft

diameter 18 in

02/10/2014 9


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Allegheny Installation


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Oct. 16th 2002

0

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120

5.09.36 AM 5.12.29 AM 5.15.22 AM 5.18.14 AM 5.21.07 AM 5.24.00 AM 5.26.53 AM

M a

i n L e v e

l ( m b a r )

0

5

10

15

20

25

30

C o n

d e n s a

t e ( m b a r ) ,

A c q u e o u s

P h a s e

( m b a r )

Level (mbar)Condensate (mbar)

Acqueous Phase (mbar)

Total Liquid829 sec., 55.320 lit.2.373 m3/h - 358 bbldDifferenc e: + 2.3%

5.11.31 am

5.25.29 am

5.18.51 am Ac queo us Ph ase340 sec., 1.57 lit.0.174 m3/h - 26.3 bbldDifference: - 2.6%

Day Average, Sep. KKY #1 - water 27 bbld, oil 323 bbld

CondensateDensity

Condensate

Density

Acqueous PhaseDensity

Mix.Density

Allegheny Installation


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0

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150

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450

500

0 50 100 150 200 250 300 350 400 450 500

Al loc ated Conden sate Pr odu cti on

V E

G A C o n

d e n s a

t e M e a s u r e

d P r o

d u c

t i o n

0

10

20

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60

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1000 10 20 30 40 50 60 70 80 90 100

Al located Acq ueou s Phase Prod uct ion

V E G A A c q u e o u s

P h a s e

M e a s u r e

d P r o

d u c

t i o n

Total LiquidCondensate

Acqueous Phase

Condensate Mean Difference: 1.9%

Acqueous Phase Mean Difference: 3.5%

Total Liquid Mean Difference: 1.8%

King Kong VEGAMeasurements of the Liquid Flow Rates


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Results of Allegheny Installation


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VEGA Installation in Ripalta (1)

In February 2006 a 12 VEGA meter was installed inRipalta, a gas storage field of STOGIT, to monitor liquidcarry-over from a dehydration column.

The specification was for a horizontal meter able to detectliquid volume fractions as low as 0.00002 %.

This objective is impossible (by orders of magnitude) forany of the available Wet Gas Meter on the market.

It is within the capabilities of VEGA because this meter isbased on a very efficient separation system, designed witha careful CFD simulation of the flow field within theseparator.


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Axial Separator


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Vega Factory


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No calibration is required. VEGA is only based on standardflow rate measurements.

High accuracy. In particular in the range of extremely lowliquid volume fractions.

Very wide rangeability.

No radioactive sources.

Only conventional oil field instrumentation is adopted.

The results of independent tests made by NEL (UK) areavailable.

Development of a new MPFM


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Presence of valves.

Self calibration requires an expert operator.

Same potential safety problems as a conventional welltesting system.

More bulky than main competitors.

Very poor marketing capabilities of TEASistemi.

Development of a new MPFM


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VIS Meter

The separator has been re-designed and its size optimized.

The mechanical construction has been deeply changed,with a substantial weight reduction.

The valves required for VIS operation have beenpositioned inside the system.

The final result is a small, low weight MPFM which can bevery easily marinized.


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VIS Layout


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10ANSI 900LB


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Conclusions

Isokinetic sampling of a gas-liquid mixture, followed byphase separation, can be an effective method formultiphase metering.

The extensive use of CFD simulations allows new, verycompact and efficient gas-liquid and liquid-liquid separators

to be designed.The technical cooperation between an academic spin-offand a major industrial company may also lead to a newproduct of potential impact on the market.


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wet gas metering by isokinetic sampling

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