© 2015 Cairn India Limited

Mechanical Integrity of Offshore Pipelines

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Agenda Importance of Pipeline Integrity? Managing Pipeline Integrity

Design & Construct

Prevent/Maintain

Monitor & Assess

Mitigate shortcomings

Case Study- Intelligent pigging at CB/OS-2 [Challenging Subsea line Pigging ]

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Importance of Pipeline Integrity? Pipeline Integrity Ensures :

Pipelines and associated components are maintained in intact/healthy condition during its design life.

Pipeline is suitable to withstand the extreme possible conditions within its design limits

Statute Compliance

Importance Helps in : Safe and efficient transportation of fluids/energy Avoiding any or all Incidents that may damage life, property and environment

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Achieving Pipeline Integrity Designing and Construction Should be based on process variables, design

life, transport fluid characteristics and all other external factors to sea condition.

Proper route surveys to minimize elevation difference of subsea pipelines

Consideration of tidal factor and geographical condition

Provision for the maintenance and monitoring

Continuous Monitoring Fe+, SRB count & Residual CI monitoring Corrosion Coupon checks LRUT of accessible pipeline / Risers ICDA/ECDA Intelligent Pigging ILI

Prevention & Maintenance Corrosion inhibition chemicals injection Cathodic protection Regular Pigging for Cleaning Annual Subsea survey Rectification of Exposed line

Mitigation Action Adjust dosing rates of Corrosion

inhibition chemicals Cathodic protection remediation Rectification Free Span Burial of exposed line Replacement of abnormal section of

pipeline

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Changes Operating conditions like Pressure/ Temperature/Flow etc. Composition of Fluid ( Gas to Liquid, Corrosive H2S, CO2 etc.) Statutory Regulations Change in Geological conditions (Tidal conditions, natural disasters) Managing Changes Up gradation of Liquid handling facility Chemical injection like H2S Scavengers etc. Identifying Free Spans/ Delineation Scouring and its rectification Complying changes in statutory regulations as per the requirement

Change Management

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Case Study _Challenging pipeline Pigging Integrity Assessment [24’’ Sub-Sea Pipeline ]

24” subsea pipeline x 35 KMs long Single pipeline _ Life line for CIL-CB/OS2 operations Commissioned in 2002 03 Major pigging campaign

1st : 2004-05 - Successful Intelligent Pigging 2nd : 2010-11 - Initiated for Intelligent Pigging but 24” Bi Di pig got

Stuck in the pipeline. Fortunate to push it back

3rd : 2014[Pilot Pigging] & 2015 [Successful Intelligent PIGGING] – Case Study

24” BI-DI PIG as Received on LA

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Key Hurdles Pigging with Mechanical Pigs on a pipeline with

history of PIG stuck scenario. Handling PIG stuck scenario without onshore

gas well Sustain maximum production rate during

Pigging, Liquid handling Offshore logistics and weather conditions. Managing entire operation from unmanned

Offshore platform.

Minimize Cost

Avoid long downtimes

Safe Operations

Case Study Integrity Assessment [24’’ Sub-Sea Pipeline ]

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Main Learning's : How to handle heavy liquid volumes Modification of Sludge Pit at PIG

receivers end Installation of re-processing

pumps at holding pond Installation of additional

Ultrasonic pig signaller to determine pig arrival

Pilot Pigging campaign [2014] helped in Pre-assessment of Pipeline Learning from this helped Man-hours and Cost during main campaign

Case Study Integrity Assessment [24’’ Sub-Sea Pipeline ]

Maintained an average of 8000 bopd Production

0% BS&W in Crude Sales

Minimum time lost between planning

and execution after awarding of contract

Based on the Outcomes of Pilot PIGGING and past experience of pig stuck

situation,we adopted “Progressive Pigging strategy” for Intelligent Pigging Campaign

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Pipeline cleaning was carried out utilising the following range of pigs Foam Pigs Medium density Pig’s HD pig’s with bristle, straps, power brush and studs

Gauging Pigs Pig’s with gauge plate – Two stages Gauge Plate run with Foam pig & Cup pig Kaliper Pig – @ two different stages

Hard Body Cleaning Pigs Pig’s with Cup slits of various configuration Pig’s with Sealing disks (570mm, 584mm, 594mm, 610mm) of various configuration Pig’s with guide disks (570mm, 577mm, 584mm) Pit-boss Pig with pencil brushes

Continuous Oil flow in to subsea line during pigging Multiple review of Gauge plate and Kaliper report

Case Study Integrity Assessment [24’’ Sub-Sea Pipeline ]

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Case Study Integrity Assessment [24’’ Sub-Sea Pipeline ]

A total of 97 pigging runs were carried out including KALIPER tool run during 15th & 80th pigging run for checking the bore of pipeline prior to running hard body cleaning tool from pigging run in pipeline

RUNS PIG TypesDEBRIS RETRIEVED (ONSHORE) KGS

MD Foam PigHD Foam PigHD Foam pig with brush, Studs, Full brush

15 Kaliper Pig 1516-32 HD Foam pig with brush, Studs, Full brush 171

33-39 Cup pig with varying numbers of slits on cup surface to reduced the aggressiveness

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40 Gauge plate with Foam pig for physical assurance 25Cup pig with different combination, Brushes, blades, Gauge platesCup with Disc of various size seal discDisc pig by varying size of seal disc outer diameter and guide disc diameter

80 Kaliper run 80th which indicated greater improvement in minimum bore dia reported by 1st Kaliper run

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81-96 Post Kaliper introduced further aggressive pigs like pencil brush, Pit boss with increased diameter of disc – 16nos

1150

97 MFL Run 1

204

41-79

1-14

2168

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Finally, 97th run [28th Apr-15], MFL tool PIG was launched and successfully received at onshore with required scan data.

Case Study Integrity Assessment [24’’ Sub-Sea Pipeline ]

Team with MFL Intelligent Pig

• The Tool Run Was Flawless • Maintained velocity range • No Debris at all with IP • No sensor Failure

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Key Achievements With flawless coordination and meticulous Teamwork , CIL-CB/OS-2 team has overcome challenges and completed the task well Maintained 99.79 % Plant Uptime with higher oil production rate Managed CTU And Platform Extension Simultaneous With Pigging We Managed To Pig Total Pipeline Length Of 3443 kilometers. Removed 8 MT of debris from the pipeline No Chemical pigging only mechanical cleaning, $2 million saving just by saying

no to chemical pigging. Launch a total of 97 PIG from initially planned 45 PIG without added cost. CB team not only sustained more than 8000 bbls/day of oil production but also recovered about 1500 barrels of oil from the slop oil by reprocessing it during campaign.

Pipeline is Qualified to continue its operations to Maximum design pressure without any de-rating and deemed to be a healthy pipeline

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Figure 1: Metal Loss Orientation Graph

Max 100 Metal Loss Groups Were Identified

Figure 2: Velocity Profile

During MFL Tool

Avg. velocity: 1.8 m/s

Key Achievements

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