inline lng measurement

Poster PO-56

PO-56.1

IN-LINE MEASUREMENT OF LNG FOR FISCAL ALLOCATION

Mike Mullally ExxonMobil Development Company

Gordon Stobie ConocoPhillips

K. H. Salavudheen Qatargas Operating Company

ABSTRACT

This paper documents a recent in-depth study on in-line measurement of LNG. Because shipboard measurement is the standard industry practice, accuracy requirements and standards for cryogenic measurement using in-line measurement have not been studied by LNG producers. A recent study demonstrates that accurate measurement of LNG with in-line meters is possible.

Shared storage and offloading facilities allows LNG exporters to share lower overall

export costs. Reduced capital cost is the major benefit of these facilities. Qatar, who is moving to become the world’s largest LNG exporter, is taking advantage of this reduced capital costs by implementing shared storage and loading facilities for its new lean LNG joint ventures. As a result of this shared offloading and storage, there is a greater need for accurate measurement of LNG rundown.

This study required that we demonstrate meter performance in actual operations using

full sized meters in LNG rundown service simulating the actual application. Knowing an “LNG prover” was not yet available for the rates in a typical LNG facility, a goal of demonstrating “near custody transfer quality” was set.

Testing was performed at an LNG facility located in Kenai, Alaska, USA. Shipboard

measurements were used to calibrate the plant’s storage tanks. The plant’s storage tanks were used in a series of production runs between liftings to demonstrate meter accuracy. The testing was also used to identify any operational issues due to the cryogenic temperatures. Over a three month period, two different technologies (coriolis and ultrasonic) were used to measure LNG into the plant’s LNG storage tanks between offloaded shipments.

Test results demonstrated that accurate metering can be achieved. Use of in-line

meters for LNG rundown is a first step towards potential use of as check meters for loading and offloading, and a potential replacement of ship measurement for custody transfer sometime in the future.

Poster PO-56

PO-56.2

ININ--LINE MEASUREMENT OF LNGLINE MEASUREMENT OF LNGCOMMON LNG PROJECT (CLP)

TECHNOLOGIES EVALUATEDTECHNOLOGIES EVALUATED

•• CoriolisCoriolis•• UltrasonicUltrasonic

•• Fiscal allocation of LNG from 8 different LNG Fiscal allocation of LNG from 8 different LNG trainstrains

•• Volumes totaling over 56 MTPA (or ~8 Volumes totaling over 56 MTPA (or ~8 Bcf/dBcf/dof gas)of gas)

•• 7 Meter stations ranging in size from 57 Meter stations ranging in size from 5--16 16 MTPAMTPA

SCOPESCOPE

Mike Mullally, ExxonMobil Development Company, Gordon Stobie, ConocoPhillips,

and K. H. Salavudheen, Qatargas Operating Company

Poster PO-56

PO-56.3


•• Currently, no way to prove LNG flow Currently, no way to prove LNG flow metersmeters

•• No LNG Industry experience for fiscal No LNG Industry experience for fiscal meteringmetering

•• Long term operability of equipment @ Long term operability of equipment @ cryogenic temperaturescryogenic temperatures

•• Potential for flashing Potential for flashing -- limited pressure limited pressure lossloss

•• ReliabilityReliability•• Means of validation (check or master Means of validation (check or master

meter)meter)•• Need for mass and/or density Need for mass and/or density

measurementmeasurement

LNG MEASURMENT CHALLENGESLNG MEASURMENT CHALLENGES

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INCENTIVESINCENTIVES•• Enabling technology for approximately Enabling technology for approximately

1 Billion USD$ in savings in project cost1 Billion USD$ in savings in project cost–– Common Storage, Fewer TanksCommon Storage, Fewer Tanks–– Shared Offloading, Fewer BirthsShared Offloading, Fewer Births–– Feed from Multiple LNG Plants Feed from Multiple LNG Plants

with different operators & ownerswith different operators & owners

•• Fiscal allocation of LNG is required as a basis for Fiscal allocation of LNG is required as a basis for operating a common storage facilityoperating a common storage facility

•• Accurate/repeatable inAccurate/repeatable in--line flow measurement line flow measurement of LNG rundown prior to commingling requiredof LNG rundown prior to commingling required

Common LNG Storage & Metering LocationsCommon LNG Storage & Metering Locations

RL3 Train 6

Lot H

Qatargas

RasGas

Lot N

RL3

Inte

rcon

nect

Line

LNG

Tra

nsfe

r Li

ne

RL (II) Train 4

QGII TR 4

QGII TR5

QG3 TR 6

QG4 TR 7

Bert

h 3

Ber

th 4

Bert

h 5

Ber

th 6

RL3 Train 7

QGII Train 4

QGII Train 5

RL (II) Train 4

RL (II) Train 5

QG3 Train 6

QG4 Train 7

RL (II) Train 5

RL3 Train 6

RL3 Train 7

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PO-56.5


•• ConocoPhillips Kenai Alaska LNG PlantConocoPhillips Kenai Alaska LNG Plant•• Comparison versus LNG tanks and custody Comparison versus LNG tanks and custody

transfer ship measurementstransfer ship measurements•• Demonstrated performance, 1+ years in LNG Demonstrated performance, 1+ years in LNG

serviceservice•• Accuracy Goal Verified Accuracy Goal Verified -- Good performance by Good performance by

both types of meters testedboth types of meters tested–– Ultrasonic meters found to be best fit for large Ultrasonic meters found to be best fit for large

flowsflows–– Coriolis meters give good performance if sufficient Coriolis meters give good performance if sufficient

differential pressure (differential pressure (ΔΔ P) is availableP) is available–– Measured Density not required for conversion from Measured Density not required for conversion from

volume to Mass. Equations of State normally volume to Mass. Equations of State normally used for custody transfer (e.g. used for custody transfer (e.g. CostaldCostald, Modified , Modified KlosekKlosek--McKinley) found to yield excellent results McKinley) found to yield excellent results on Densityon Density

FIELD TESTED IN LNG SERVICEFIELD TESTED IN LNG SERVICE

Poster PO-56

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•• No pressure dropNo pressure drop•• Demonstrated performance in LNG serviceDemonstrated performance in LNG service•• Reliability: Reliability:

–– 88--Path Meter Path Meter –– Each 4Each 4--path group operates as an independent meter & will path group operates as an independent meter & will

continue to operate if the other 4continue to operate if the other 4--path group has a problempath group has a problem•• No need for flow conditioner (reduced No need for flow conditioner (reduced ΔΔP) P) •• Correction for swirl Correction for swirl •• BuiltBuilt--in check meter: Redundant 4in check meter: Redundant 4--path design employedpath design employed•• Accuracy: Accuracy:

–– GOAL GOAL –– 0.5% or better0.5% or better–– Minimize bias due to swirl by averaging the two 4Minimize bias due to swirl by averaging the two 4--path groupspath groups–– Averaging two flow rates reduces the measurement uncertaintyAveraging two flow rates reduces the measurement uncertainty

1st 4-Path group

1st 4-Path group

2nd 4-Path group2nd 4-Path group

ULTRASONIC METER TECHNOLOGY SELECTEDULTRASONIC METER TECHNOLOGY SELECTED

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INTEGRATED SYSTEM DESIGNINTEGRATED SYSTEM DESIGN

•• Central WorkstationCentral Workstation•• Remote AccessRemote Access•• Integration of Integration of

–– USM DiagnosticsUSM Diagnostics–– Field Transmitters Field Transmitters

DiagnosticsDiagnostics–– Flow ComputersFlow Computers–– Gas ChromatographsGas Chromatographs–– Flow Management SystemFlow Management System–– Plant HistorianPlant Historian–– DCSDCS

GC

RemoteAccess

IntegratedComputer

System

FlowComputers

FieldInstrumentation

MOVzs

PT

Redundant USMTT TT

MOVzs

PT

Redundant USM

TT TT

MOVzs

PT

Redundant USMTT TT

Dell 1800

Dell 1800

Dell 1800

Dell 1800

Dell 1800

Dell 1800

Flow ManagementSystem

PlantHistorian

DCS

•• Potential future use for Potential future use for USMUSM’’ss as check as check measurement for tanker volumesmeasurement for tanker volumes

•• Potential future use for either USM or Potential future use for either USM or coriolis as key process meters in terminals coriolis as key process meters in terminals and plantsand plants

FUTURE POTENTIALFUTURE POTENTIAL

inline lng measurement

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