CS-003 (pipeline integrity monitoring-transandean route)04.pdf

8/14/2019 CS-003 (pipeline integrity monitoring-transandean route)04.pdf

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The challenge

> Ground movement >Geohazard > Water level > Leak detection

Integrity Monitoring ofTrans Andean Pipeline

The 34 high pressure gas pipeline, operated by Peru LNG (1),

which joins the Transportadora de Gas del Per (TGP) pipelineto the Peruvian coast is 408 km (250 mile) long and reaches

an altitude of nearly 5000 m (16,000 ft.). Three aspects make

this a particularly challenging region for pipeline installation and

operation.

Firstly, the topology and geology, (landslides and erosion cause

over 50% of pipeline incidents in the region) with slopes of up

to almost 45 requiring extensive measures to limit erosion

and water run-off. Secondly the climate, with hot, dry periods

followed by heavy rain causing erosion and landslides. Thirdly,

the evolution of water levels surrounding the right-of-way is a

constant threat in certain areas.

A solution was sought to monitor ground movement and changing

water levels reliably over the 60 km pipeline section whichcrosses the Eastern slopes of the Andes. Remote operation and

control was required, since no local installation or maintenance

was possible. Since most of the pipeline right-of-way is isolated,

remote and difficult to access, traditional geotechnical monitoring

techniques and patrolling could provide only partial information.

1 - PERU LNG consortium comprises: Hunt Oil Company, SK Energy, Repsol and

Marubeni Corporation.

PIPELINE

Case Study

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Omnisens SA

Riond Bosson 3, 1110 Morges Switzerland

T: +41 21 510 21 21 - F: +41 44 274 20 31

[email protected]

www.omnisens.com

PIPELINE

Case Study

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The solution

Fiber optic distributed sensing provided an ideal match to the

requirements for ground movement and temperature monitoring

in these challenging conditions. The Omnisens Brillouin-based

DITEST AIM system was selected since with one interrogator

ground movement (via strain monitoring) and changing water

levels (via temperature monitoring) could be accurately detected

and located over the 60 km section in the Andes Mountains. Leak

detection is provided by the temperature monitoring performed

continuously along the pipeline.

The system comprises an interrogator unit placed in the first

valve station at kilometer 30 and a server in the control room

at Pampa Melchorita for data processing, analysis and storage.

The server also generates alarms, sending these to the SCADA

system, as well as sending a email to nominated recipients.

(email alarming service).

Two separate sensing fiber cables are placed alongside the

pipeline, (both with single mode communications grade fibers).

The strain measurement cable, SMC, is a dedicated specialty

fiber optic cable that has one fiber held in a flexible structure sothat it accurately reflects the strain of the soil moving around it,

while spare fibers within the fiber optic telecommunication cable

were used for temperature sensing.

Soil movement, likely to be a precursor to pipeline movement,

deformation and eventually rupture, is detected and precisely

located early and then continuously monitored, enabling the

operators to take action quickly. The SMC strain sensing cable

(IEC 794-1 compliant) included in the trench provides this early

warning of soil movement. Any elongation of this sensor cable

is detected and located by the Omnisens system, which sends

an alarm to the control system when the strain exceeds user-

defined thresholds. Sensitive enough to detect small groundmovement (in the 5 cm range) it is crush and abrasion resistant,

rodent-proof, with a life expectancy of 30 years or more.

The temperature is monitored using fibers from the

communications cable, buried in the trench approx. 10 cm from

the pipeline upper surface. Temperature event and location

data arrive at the interrogator, allowing the Omnisens system to

monitor water level changes and incipient leaks using automatic

leak detection algorithms. This fiber optic cable is also used for

communication between the Omnisens DITEST interrogator and

the server.

Melchorita Camisea

Pipeline route, showing area to be monitored in green rectangle

Blue line - Peru LNG pipeline

Red line - TGP pipeline

BOLIVIA

BRAZILPERU

200 miles

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Pisco

Ayacucho

MachuPicchu

NEW PIPELINEOMNISENS SERVER

OMNISENSINTERROGATOR

Campo Malvinas

Chiquintirca

Pampa Melchorita

il

6000

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5000

4000

3000

2000

1000

1000 100 180 km

Rio Yucaes

Rio Torobamba Rio ApurimacAyacucho

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Results

Shortly after pipeline operation commenced, the Omnisens

system gave early warning of a number events, all verified by

patrols, allowing the operator to reinforce the pipeline right-of-

way where necessary before that asset was impacted.

Event 1 - Rockfall

A sudden increase in strain raised an alarm through the SCADA

system. The alarm signaled a strain event at point KP27 + 900.

Investigation of the area showed that rocks had fallen, displacing

the optical fiber sensor. This rock fall was as a result of a tension

crack higher up the slope. Reinforcements were made to the areato secure the pipeline.

System configuration

Omnisens systems comprise one interrogator to monitor both

temperature and strain over a given distance with meter spatial

resolution. The fiber optic sensing cables (TMC for temperatureand SMC for strain) are allocated to different channels on the

interrogator, so that the user can quickly see if the event is strain

or temperature related.

When pipeline operations began a reference for both temperature

and strain was obtained. Zones were programmed, reflecting the

particular conditions of each pipeline length. The alarms and

zones are programmed independently for each sensing cable

with connection to the SCADA system and an email alarming

service, so that an email is sent each time an alarm is recorded.

Pipeline in trench, with Temperature Measurement Cable (left,

orange), and Strain Measurement Cable (right, blue).

Earth movement can be controlled by gabion walls, constructed

as prevention or in response to the detection of a creeping

landslide detected by the Omnisens system.

Omnisens SA


T: +41 21 510 21 21 - F: +41 44 274 20 31

[email protected]

www.omnisens.com

PIPELINE

Case Study

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Omnisens SA


T: +41 21 510 21 21 - F: +41 44 274 20 31

[email protected]

www.omnisens.com

PIPELINE

Case Study

4

References

Esford, F. Porter, M. Savigny, K W. Muhlbauer, W K. Dunlop, C. A

risk assessment model for pipelines exposed to natural hazards,

Proc. 5th International Pipeline Conference, American Society of

Mechanical Engineers (2004).

Introduction to land-use and climate change impacts on

landslides Winter, M.G., Dixon, N., Wasowski, J. and Dijkstra,

T.A. Quarterly Journal of Engineering Geology and Hydrogeology,

43, 367-370, 2010

Hauswirth, D., Iten, M., and Puzrin, A. M. (2011)."Experimental

study of a soil-embedded fibre optic strain sensor crossing a

shear zone". In 5th International Conference on Structural Health

Monitoring of Intelligent Infrastructure SHMII-5, Cancun, Mexico.11-15 December 2011

Geohazard prevention with online continuous fiber optic

monitoring Fabien Ravet, Edilberto Gutierrez Ortiz, Brian

Peterson, Greg Hoglund, Marc Nikls. Rio Pipeline Conference

2011 (IBP 1277_11)

Geohazard prevention with online continuous fiber optic

monitoring Ravet, F. Ortiz, GO. Peterson, B. Hoglund, G. Nikls,

M. Rio Pipeline Conference 2011 (IBPI 1277_11)

Conclusion

The Omnisens system answered Peru LNGs requirement for real

time continuous condition monitoring of the Andean section of

the project. It was able to detect early signs of ground movement

and profile their evolution over time, as well as monitor changing

water levels reliably and continuously, over 60 km, from a single

interrogator located remotely.

This was the information that the operator needed to carry out

rapid and appropriate and strain relief on the pipeline and soil

reinforcement, helping ensure the safe operation of this pipeline

along this particularly challenging part of its route.

Event 2 - Soil movement

A strain event was indicated by the Omnisens system which, on

inspection, was due to seepage (possibly from a collapsed water

channel). This seepage led to the partial collapse of the right-of-

way. The pipeline was not damaged.

DITEST is a trademark of Omnisens

CS-003(PipelineIntegrityMonitoring-TransAndeanroute)en-04.pdf

Slopes of up to 45 0require extensive measures to limit erosion.

CS-003 (pipeline integrity monitoring-transandean route)04.pdf

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