randy allen leak

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Leak Detection

Performance

Pipeline Safety Trust Conference

November 17 & 18, 2011

New rleans, !ouisiana


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Detection?


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Why Leak Detection? (Contd)

Minimize the volume of lost uid

Reduce risk of re! e"#losion or other safety hazards Protect the com#any

Minimize cleanu# costs $ith an early res#onse to a leak$arnin%

Protect re#utation

Demonstra&le acce#tance of res#onsi&ility &y e"ecutin%a #roactive leak detection #ro%ram

'l$ays increasin% re%ulatory interest in #i#elineinte%rity #ro%rams includin% leak detection

November 17 & 18, 2011 Pipeline Safety Trust

2011 Pipeline Safety Conference3


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istory

Manual #ressure*o$ readin%s and evaluation

+oice communication &et$een the eld and anycenter of res#onsi&ility that may e"ist! or $ithother stations alon% the line

,amiliarity $ith the #i#eline &ehavior &ycontrollers and technicians $as critical

Ri%ht-of-$ay o&servation includin% $alk-overs andy-overs $ere amon% fe$ leak detection o#tions


2011 Pipeline Safety Conference


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'utomated Measurements

Pro#rietary lo%%in% systems and .C'D'

/ransmitter and meter technolo%y

'utomation tools and #roducts that ac0uireaccurate information a&out hydraulic &ehavior

/ools to assist in evaluatin% the relationshi#samon% measurements


2011 Pipeline Safety Conference!


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Leak Detection

Performance ,rom the former 'P1 2233 (4valuation Methodolo%y for

.oft$are 5ased Leak Detection .ystems)6

/he system correctly indicates that there is no leak

/he system correctly indicates that there is a leak

/he system incorrectly indicates that there is a leak(false alarm)

/he system incorrectly indicates that there is no leak(failure to detect)

Denitions a&sor&ed into 'P1 RP-2278 (Com#utationalPi#eline Monitorin% for Li0uid Pi#elines)

November 17 & 18, 2011 Pipeline Safety Trust 2011 Pipeline

Safety Conference"


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Performance Metrics

.ensitivity 9 Com&ination of the size of a

detecta&le leak and the time re0uired to detect it

Relia&ility 9 ' measure of the system:s a&ility toaccurately assess $hether a leak e"ists or not

'ccuracy 9 /he a&ility of a system to estimate leak#arameters such as leak o$ rate! total volumelost! and leak location

Ro&ustness 9 /he a&ility of a system to continue tofunction durin% unusual hydraulic conditions or$hen data is com#romised




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Meter-5ased Leak

Detection Most $idely used method on lon% haul #i#elines

Re0uires meters at all entry and e"it #oints

'chieva&le sensitivity limited &y meter accuracy

.ome methods can &e im#lemented in .C'D' or areo#tions $ith .C'D' #roducts

.ome #roducts are stand-alone and driven &y .C'D' data

'larm thresholds must tolerate and e"#ect the im&alance

in meter readin%s as the line #acks and un#acks Leak evaluation al%orithms that correlate actual chan%es

in line#ack $ith meter im&alance #rovide the &est#erformance




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'P1 22;< Performance

Predictions

Predicts the theoretical &est #erformance #ossi&le

$ith con%ured uncertainties =o mar%in for false alarm #revention

/em#erature uncertainty and related chan%es indensity durin% transit is lar%est inuence on#erformance

=ot uncertainty in measurement! &ut uncertainty intem#erature #role alon% the line

>ne ty#e of leak detection system can more accuratelyestimate the tem#erature #role than other systems


2011 Pipeline Safety Conference#


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Denitions

Dry +olume 9 +olume of the #i#eline at atmos#heric#ressure and a reference tem#erature

Line#ack 9 /he incremental 0uantity of uid in the linein addition to the dry volume inuenced &y #ressureand uid tem#erature

Line#ack is heavily inuenced &y tem#erature:s eect onuid density as is #ressure! &ut often to a lesser de%ree

Prole 9 +alue of a #arameter over the len%th of the#i#eline se%ment




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Denitions (cont)

@ncertainty 9 Potential error in measurements thatmust &e e"#ected and accounted for also the

de%ree to $hich somethin% is unkno$n and must&e estimated or assumed &ased on some$hatrelated measurementsA

Real-/ime /ransient Model (R//M) 9 'ccurately

tracks uid tem#erature*density #roles $ithconsideration of #ressure in order to reduceuncertainty in the line#ack




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Meter Buality vsAPerformance




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Meter-5ased Leak 5asics

,lo$*Pressure*/em#erature measurements only at

se%ment end-#oints

Metered o$ accuracy im#ortant for hi%h sensitivity

,luid density (molecules*mass #er unit volume)

varies si%nicantly $ith tem#erature Warm uid is less dense Cold uid is more dense

/em#erature*density #role uncertainty is the mostlimitin% factor in leak detection for some #i#elines

November 17 & 18, 2011 Pipeline Safety Trust2011 Pipeline Safety Conference

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+olumetric ,lo$Measurement

5enets of volumetric (not corrected for tem#erature

and #ressure) o$ measurement 5arrel-to-&arrel assessment tolerates dierences in

density at inection and delivery #oints

/olerates s$itchin% inection sources of dierenttem#eratures

@seful on short lines $ith small chan%es intem#erature*density durin% transmission

=ot useful $here tem#erature*density #roles aresi%nicant due to heat loss


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=et &arrel ,lo$Measurement

5enets of net (corrected for tem#erature and

#ressure) o$ measurement @seful for custody transfer

@nder steady-state conditions! uid inected at lo$erdensity $ill &alance $ith delivered uid at hi%her

density 1nections at sli%htly hi%her volumetric o$ &alances

$ith deliveries at lo$er volumetric o$

'ssumes a sta&le tem#erature*density #role


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=et ,lo$ Measurement1ssues

/ransient conditions th$art many al%orithms

involvin% net o$ measurements Line #ackin% and un#ackin% still result in an a##arent

net o$ im&alance as $ith &asic volume &alancemethods

=et &arrel o$ measurements a%%ravate sim#le&alance al%orithms $here a dierence in densitye"ists at inection and delivery #oints e"ce#t understeady-state sta&le conditions


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=atural ,lo$ 1m&alance

Dierence in inected uid density and delivered

uid density radual chan%e in uid density durin% transit

/em#erature*density #roles are #oorlyunderstood &y most sim#le al%orithms

Prole chan%es sha#e $ith chan%es in o$ rate

Water crossin%s and occasionally $et soil increasethermal conductivity


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Meter-5ased Leak DetectionLimitations

'ccountin% for chan%es or distur&ances in line#ack

>#erational chan%es causes the line to #ack orun#ack as a normal occurrence

.hort-term hydraulic distur&ances (transients)!includin% chan%es in inection tem#eratures! and theireect on line#ack must &e tolerated or understood inshort-term evaluation al%orithms used in ra#idassessments

>ver e"tended #eriods any eects of transients arediluted thus allo$in% %ood sensitivity &y most meter-&ased solutions over lon% o&servation intervals


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Eey Conce#ts

Pressures and tem#eratures under steady-stateconditions #rovide current line#ack characteristics

Diver%ence of meter readin%s (%reater im&alance) should&e reected in line#ack chan%es as seen in #ressures /ransients distur& this information and can lead to

si%nicant short-term line#ack uncertainty >ver lon% time intervals any o&served variations in

line#ack &ecome insi%nicant com#ared to the 0uantity

of uid #assin% throu%h the #i#eline system Lon%-term sensitivity settin%s do not re0uire as much

tolerance of line#ack uncertainty as do short term leakdetection thresholds


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Line#ack 4stimation

,luid density assumed to &e an avera%e of inection

and delivery density Wei%hted avera%e

Custom al%orithms for curve ttin%

R//M thermal models track uid density alon% the

line

Chan%e in o$ rate alters the tem#erature*density#role as a ne$ 0uiescent state develo#s


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Proles

/em#erature

>ccurs $hen inection and delivery tem#eratures dier

.u&ect to heat transfer characteristics of environment

+aries $ith o$ rate * transit time

Pressure

+aries as &atched uids of dierent characteristics travel

+aries as &atches of dierent densities travel over mountains

Proles are accurately tracked &y Real-/ime /ransientModels

November 17 & 18, 2011 Pipeline Safety Trust 2011 PipelineSafety Conference

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Real-/ime /ransient Model

Most so#histicated volume*mass &alance tool

1ncludes a thermal model to increase the accuracy of

line#ack evaluation! thus allo$in% a shorter detection timefor a detecti&le leak

/racks heat transfer alon% the line and develo#s accuratetem#erature*density #roles as ste# chan%es in o$ rates

or inection tem#eratures occur

'llo$s thermal model tunin% to achieve the &est#erformance &y modelin% the hydraulic &ehavior accurately

'utomatic tunin% ca#a&ilities

1nstrument sanity checkin%


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R//M Myths

.oft$are is e"#ensive

=ot si%nicantly more e"#ensive

.oft$are re0uires s#ecial skills /rainin% and full technical su##ort is oered &y vendors

Eno$led%e of the #i#eline #hysical details is needed

.oft$are re0uires on%oin% maintenance

=ot needed! once #erformance is satisfactory! &utfurther tunin% is often #erformed to continually im#rove#erformance

Re0uired if the #i#eline net$ork is chan%ed


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.tatic Pressure /estin%

4"tremely hi%h sensitivity

Fero (8) o$ results in zero (8) uncertainty in o$measurement

Works $ell in a relatively incom#ressi&le li0uid

environment

Re0uires #ressure control e0ui#ment


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.tatic Pressure /estin%(contd)

.hut in under #ressure at near o#eratin% #ressure

Monitor #ressure decay for a #eriod of time

Dro# #ressure &y half

Monitor #ressure decay for a #eriod of time

' consistent #ressure decay rate indicates

decreasin% density due to heat transfer ' dierent #ressure decay rate indicates a leak

$hose rate is #ressure de#endent


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.tatic Pressure /est /rends


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Conclusion

.im#le line#ack assessment al%orithms have a #lace$here line#ack is sta&le and line#ack variations and

uncertainty do not adversely aect leak assessment

R//M technolo%y si%nicantly reduces line#ackuncertainty in transient environments and ena&les leak

detection a##roachin% the limits im#osed &y meteraccuracy

.tatic #ressure testin% is a useful inte%rity verication tool

Matchin% the #ro#er tool to the #i#eline:s o#eration iscritical


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/rainin% G Res#onse

' critical com#onent of any #i#eline inte%rity

mana%ement #ro%ram Res#onse #rotocol should &e included in trainin% and

&e enforced Controller can shut do$n the line on any sus#icion of a

leak

Details re%ardin% actions! re#ortin%! etcA =o internal #enalty for reasona&le ud%ment

' culture focused on #i#eline inte%rity mana%ement iscritical


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References

'P1 2278 9 Com#utational Pi#eline Monitorin% for Li0uidPi#elines

'P1 22;< 9 Pi#eline +aria&le @ncertainties and /heir 4ects onLeak Detecta&ility

'P1 22H2 9 uidance Document for the Bualication of Pi#elinePersonnel

;< C,R Part 2= >, ='/@R'L '=D >/4R'. 5J P1P4L1=46 M1=1M@M ,4D4R'L .',4/J ./'=D'RD.

;< C,R Part 2= >, 'F'RD>@. [email protected] P1P4L1=4


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Contact @/.1

UTSI - U.S. Headquarters

23H8 West 5ay 'rea 5oulevard

.uite 788,riends$ood! /e"as @.' KK3;H

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,a"6 2 I2 ;8 884mail6 infoNutsiAcom

WWW6 htt#6**$$$AutsiAcom

Daniel WA =a%ala ([email protected])

President G C4>

November 17 & 18, 2011 Pipeline Safety Trust30

UTSI - EuropeRaimundo ,ernandez +illaverde ;7!

HL

I887 Madrid! .#ain

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randy allen leak

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