eLearning – Part 1 of 2 - ISA Calgary Section › wp-content › uploads › 2016 › 01 › e...E-RTTM > 0.5% Very short Short Spontaneous and creeping leaks Slight High Leak localization

Pipeline leak detectioneLearning – Part 1 of 2

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Title here again in Arial 24 max. one lineAgendaPipeline leak detection

Historical developmentLeak detection system requirementsCauses of leaksLeak detection optionsNon-continuous leak detectionContinuous external leak detectionContinuous internal leak detection

Title here again in Arial 24 max. one lineAgendaPipeline leak detection

Leak localizationHuman Machine InterfaceAdditional functions in leak detectionTypical applications of leak detection systems

IntroductionHistorical development

3 | Pipeline leak detection

3000 BC 500 BC 400 BC

Copper pipes for water transport

First transport ofhydrocarbons

Supplying Peking with natural gas

Factors influencing the construction of pipelines:

Discovery of crude oil

Development of refineries

Dependency of oil transport

Invention of the automobile

IntroductionHistorical development


19th century

IntroductionCurrent situation

| Pipeline leak detection5

Oil, crude oil, refined products, natural gases, condensate, process gases, water and salt water

Title Contents of requirement

Leak detection system requirementsOfficial requirements


TRFL Technical Rules for Pipelines

API 1130 Computational Pipeline Monitoring for Liquids

API 1149 Pipeline variable uncertainties and their effects on leak detection

API 1155 (replaced by API 1130) Performance criteria for leak detection systems

CSA Z662 Oil and gas pipelines

49 CFR 195 Transport of hazardous liquids via pipeline

Leak detection system requirementsPerformance criteria

8PipePatrol E-RTTM8 | Pipeline leak detection

Label Description

Reliability• Avoid false alarms

• Reliably detect leaks

Accuracy • Accurate localisation of leaks

Robustness• Detect failing sensors

• Fall-back strategies in the event of sensor failure

Sensitivity• Minimum detectable leak rate

• Detection time

F

Causes of leaks


In Out

Fatigue cracks

Stress corrosion

Hydrogen indexing

Material manufacturing errors

External influence

Leak detection options


Non-continuous Continuous

External systems

• Fibre optic cable

• Acoustic systems

• Sensor hoses

• Video monitoring

Internal systems

• Pressure point analysis

• Mass balance method

• Statistical systems

• RTTM-based systems

• E-RTTM

• Inspection by helicopter

• Smart pigging

• Tracking dogs

Leak detection systems

Non-continuous leak detectionInspection by helicopter

Leak detection methods:

Laser

Infrared camera

Leak sniffer

Usage conditions:

Detecting small gas leaks

Accuracy depends on weather conditions

Poor weather conditions make helicopter flight difficult


Non-continuous leak detectionSmart pigging


Types of pigging:• Cleaning pigs• Batching pigs

Smart pigs• Magnetic flux leakage method• Testing using the principle of ultrasonic

Non-continuous leak detectionSmart pigging


Usage conditions:Detecting existing and potential leaksZero or baseline piggingPipeline must be piggableAccuracy of measurement depends on the pig velocity

1 - 5 m/s

Non-continuous leak detectionTracking dogs

Trained to smell certain odorant

Usage conditions:

Short pipelines, segments

Containment of leak sites

Certification difficult


External leak detectionFiber optic cable

Usage conditions:

Accurate localisation of leaks

Limited length possible


Laser

0 s

°C

Many reflections required

Cable position must be selected according to the medium

Gas

Liquids

L

Usage conditions:

Acoustic sensors directly on the pipeline or with steel rods for underground pipelines


sL

A AA A A A

• Large number of sensors for longer pipelines

Difficult to detect small leaks

0

dB

A

External leak detectionAcoustic systems

External leak detectionVideo monitoring


Usage conditions:

Short distances

Continuous leak detection may be possible

Pump

External leak detectionSensor hoses

Usage conditions:Monitoring short pipelinesSmall leaks detectableCable position must be selected according to the medium


Gas detector

Pump time

Gasconcentration

∆

Internal leak detection


PLTLP0 T0

Internal leak detectionOverview of the systems

Extended-RTTM

Volume comparisonmethod

Statistical systems RTTM-based

P T P T

Pressure point analysis


t0

dp/dt

Internal leak detectionPressure point analysis


In

P

Out

Upper threshold

Lower threshold

Internal leak detectionMass balance method


30

25

20

15

10

5

0

30

25

20

15

10

5

0

Difference

Uncompensated mass balance

In/Out

InOut

Out In

Internal leak detectionStatistical systems


In Out

LeakNo leak

Alarm

Probability

Statistical variable

Internal leak detectionRTTM

Conservation of Mass

Real-Time Transient Model

Conservation of Momentum

Conservation of Energy

In Out

L

PL

Internal leak detectionRTTM


TLP0 T0

F0 FL

∆

Change in pipe contents

Change in pipe contents

RTTM-compensated mass balance

t

= compensated leak rate

Internal leak detectionE-RTTM


PLTLP0 T0

F0

∆

Residual x ≡ F0 – F0 Residual y ≡ FL – FL

∆

FL

F0 FL

Internal leak detectionE-RTTM


PLTLT0P0

F0 FL

F0 FL

∆

s

Residual x ≡ F0 – F0 Residual y ≡ FL – FL

Residuals x and y are used by the system as decision values

Leak signature

x

∆

Internal leak detectionCapabilities of internal systems

Method Typical min. detectable leak rate

Time to detect leak (liquids)

Time to detect leak (gases)

Detectable types of leak

False alarm frequency

Accuracy of leak localisation

Pressure point analysis

> 5% Short Long Spontaneous leaks

High High with additional pressure sensors, dependent on sampling rateMass balance

method> 1% Long Very long Spontaneous

and creeping leaks

High Average with additional pressure sensors

Statistical methods

> 0.5% Long Very long Spontaneous and creeping leaks

Slight Average with additional pressure sensors

RTTM > 1% Short Short Spontaneous and creeping leaks

Average High

E-RTTM > 0.5% Very short Short Spontaneous and creeping leaks

Slight High

Leak localizationOverview

Possibility of combining methods

Improving accuracy

Reducing problems in localizing


Gradient IntersectionMethod

s

p

Wave PropagationMethod

t

sExtended Wave Propagation

Method

t

s

Leak localisationGradient Intersection Method


p

sL0 sLeak

In

P

Out

P

p0

pL

Advantages• Localising: spontaneous, creeping leaks • Good accuracy with stationary operation Disadvantages• Accuracy depends on length of pipeline• Pipeline geometry must be taken into consideratio

Leak localisationWave Propagation Method


t

sL

sLeak

p0

pL

tLeak

Δt

0

In

P

Out

P

Advantages• Good accuracy

Disadvantages• No localizing of creeping or small leaks • Fast sampling required

• Can be used during operation and pauses

Leak localisationExtended Wave Propagation Method


t

sL

sLeak

p0

pL

tLeak

0

In

P

Out

P

• Good accuracy

P P

p2

p3

HMI (Human Machine Interface)


HMI (Human Machine Interface)


Added functions in leak detectionEfficiency analysis


87% efficiency

100% efficiency

Inventory calculation

Operator training

Theft detection

Hydraulic profiles


Added functions in leak detection

Added functions in leak detectionBatch tracking


Batch trackingTracking products and mixing zones

Batch schedulingScheduling arrival times and capacities

Scheduling of delivery

Reducing waste

Typical applications


Typical applicationsFPSO to refinery


• Long pipelines with large diameters• Substation measurements impossible

Typical applicationsOil field to refinery


• Long pipelines with large diameters• Changes in viscosity and density• Elevation and temperature differences

Typical applicationsOffshore drilling rig to refinery


• Changes in viscosity and density• Substation measurements impossible• Large diameter

Typical applicationsRefinery to tank farms


Several products with various densities

Typical applicationsGas field to refinery


• Long pipelines with large diameters

• Elevation and temperature differences

Typical applicationsChemical plant to chemical plant


Heavily transient operation of pipelines

Typical applicationsSea to city


Long pipelines with large diameters

Choosing the right leak detection system

No leak detection system isthe perfect choice for every application

Selection of the system depends on:

Desired results

Costs

Installation conditions

Individual adaptation leads to optimal performance


What requirements are placed on the application?

Title here again in Arial 24 max. one lineSummaryPipeline leak detection

1. Historical development2. Leak detection system requirements3. Causes of leaks4. Leak detection options5. Non-continuous leak detection6. Continuous external leak detection7. Continuous internal leak detection

Title here again in Arial 24 max. one lineSummaryPipeline leak detection

8. Leak localization9. Human Machine Interface10. Additional functions in leak detection11. Typical applications of leak detection systems

Thank you for your attention.

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eLearning – Part 1 of 2 - ISA Calgary Section › wp-content › uploads › 2016 › 01 › e...E-RTTM > 0.5% Very short Short Spontaneous and creeping leaks Slight High Leak localization