Lessons Learned in Subsea Pipeline Integrity Management

2015 FC Business Intelligence

The information of this document was prepared by Upstream Intelligence (part of FC Business Intelligence) and its partners. Upstream Intelligence has no obligation to tell you when information in this document changes. Upstream Intelligence makes every effort to use reliable, comprehensible information, but we make no representation that it is accurate or complete. In no event shall Upstream Intelligence and its partners be liable for any damages, losses, expenses, loss of data or profit caused by the use of the material or contents of this document.

Upstream Intelligence grants you a license to make one free copy of the information contained herein for personal or non-commercial use only. Accordingly, no part of this document may be copied, performed in public, broadcast or adapted without Upstream Intelligences prior written permission.

Please contact Kerr Jeferies at [email protected] to request permission.

Cover photo courtesy of Jee

Lessons Learned in Subsea Pipeline Integrity ManagementFrom Design to Decommissioning

By Grant AdamHead of IMJee

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3rd Annual Subsea Integrity Summit

Avoid subsea asset failure, mitigate integrity risks & secure reliable subsea systems to boost production performance.

October 5-6, Houston TX

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Subsea Pipeline IM: from design to decommissioningAccording to the Bureau of Ocean Energy Management (BOEM), The Gulf of Mexicos oil and gas industry is one of the most developed in the world. Boasting more than 3,000 platforms, operating in waters up to 650 feet deep, with many rigs drilling in waters depths in excess of 3,200 feet. To support this is an infrastructure of more than 28,000 miles of oil and gas pipeline, many of which were constructed up to 40 years ago thus at a high risk from an integrity standpoint.

Grant Adam, Head of Integrity Management at Jee Ltd, the leading independent multi-discipline subsea engineering and training firm, reviews the primary risks threatening ageing assets and subsea pipeline integrity, and the management and mitigation measures that can be employed to reduce these.

Introducing the problem

The consequences of ineffective integrity management of this expanse of ageing subsea pipelines can be catastrophic. Offshore pipelines carrying hazardous substances with poor integrity management have the potential to be disastrous from an economic, social, environmental, and possibly legal standpoint.

Significant failures in both gas and liquid pipelines have made global headlines, like the Prudhoe Bay oil spill in Alaska where up to 5,053bbl of hydrocarbons were spilled over 7,700 m2, with the spill having originated from a 0.64cm hole in an 86cm diameter pipeline.

Although pipelines are statistically very safe and reliable, past pipeline failures such as this have resulted in fatalities and substantial damage to the environment.

In an industry where subsea assets are maturing and reaching the end of their design lives, effective integrity management has never been more important, ensuring reliability of offshore installations, wells, well control equipment and pipelines throughout their life cycle.

Pipelines can be subject to a range of degradation issues e.g. corrosion, erosion and embrittlement, a progressive deterioration known as ageing. Effective and consistent integrity management is integral to ensure safe and efficient operation and provides operators with an accurate picture of the current condition of the system, and the activities required to maintain system integrity.

Lessons learned and best practices in achieving subsea pipeline integrity management help to ensure the risks involved in the ageing process are reduced, and the long, safe and reliable life of pipelines achieved.

Reviewing how to safely maximise the profitability of mature assets through robust life extension processes, gaining an insight into the foundations of subsea pipeline integrity established as early on as the design phase, understanding how integrity is continued into the next phase, decommissioning, and learning how to develop the key processes and systems that will ensure safe, reliable operation, is all instrumental in achieving this.

Lessons Learned in Subsea Pipeline Integrity Management





Failure of pipelinesWhen the corresponding failure rate is plotted against time, a bathtubshaped curve results (Figure 1) which highlights higher rate of failure in early and late life.

Figure 1: Bathtub-shaped curve results of life of pipelines against number of failures

The first phase of the diagram shows failure rates in early life caused by design, construction or installation mistakes and damage. Higher rates of early life failures are more common when new technology or design approaches have been used. For example, a number of failures were seen when pipe-in-pipe systems were first employed to solve high temperature flow assurance problems. Many of these failures were associated with failure of the welded connections. From experience of these failures and the maturing of the technology, this high early life failure rate is reduced.

In the middle phase there is a steady state of low rate failures during the operational life of the asset. This represents a gradual deterioration during the service life but generally a manageable rate of decay.

The final phase shows late life failure due to ageing of the pipeline system. However, some pipelines suffer from premature ageing which results in a high rate of deterioration within the design life of the pipeline, leading to substantially more inspection and repair to keep the pipeline operating.

By preventing, detecting or mitigating defects, you can significantly reduce the risk of pipeline failure.


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Designing for integrityWhen designing a pipeline and any modifications to it, it is essential to take into account the threats to the pipeline system and ensure the design approach reduces the risk to as low as reasonably practicable. These threats include the operating management, the fluid to be conveyed and the external environment.

Pipeline design is also the starting point for inspection, testing and maintenance, with the pipeline design determining the ease with which it can be inspected using techniques like inline inspection tools.

Some key aspects of design that have a strong influence over the operational integrity include:

Material selection

Flow assurance

Expansion and buckling

Early involvement of the operations team in the design phase helps to ensure knowledge transfer, and establish integrity from the beginning. This allows the team to address and resolve any potential issues early in the assets life. Making the right design choices can have a significant positive or negative impact on the integrity management of a pipeline. It is extremely valuable to discuss design, its intent, and the potential challenges it possesses, in order to tease out issues and prevent repeat mistakes.

Building integrityThe construction and installation of the pipeline system brings a high risk of damage or introducing imperfections in the pipeline, which can result in failure later in life. This may be due to a number of causes including the installation analysis targets not being met or the analysis being performed incorrectly. The depth of the burial target not being achieved can cause major implications including spanning, movement and instability of pipeline. Another possible cause is the loss of concrete coating which can result in further instability issues. In some cases, a pipeline could become buoyant in the water and start to float, which would lead to serious and expensive repair work. Achieving the design through installation is crucial to ensure a pipeline behaves late in life.

There are a number of pipeline build phases that are subject to threats to the integrity of the pipeline, including:

Construction

Installation

Pre-commissioning

Commissioning

Detailed and quality handovers to the operations team is critical to ensure that risks to the system are managed during this time of change.


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Integrity during operationManagement system

During operation a pipeline integrity management system (PIMS) is used to describe the framework for managing the pipelines integrity. An effective PIMS is critical to prevent failures, with analysis of the data collected on the pipeline over a period of time helping with improved monitoring, reliability, availability and compliance to regulatory guidelines in the operation of the pipeline systems.

Effective management of pipeline systems is essential for safe and reliable pipeline operations. The PIMS achieves this through definition of the following aspects:

Roles and responsibilities

Competencies

Integrity process and tools

Change management

Compliance with regulations and standards

CASE STUDY - Pipeline integrity management systems (PIMS)

An example of when a PIMS was essential to ensure integrity management was when a major operator, with assets in numerous global locations, wished to develop a new pipeline system in the Middle East to transport sweet gas from four wells to a third party processing facility. A PIMS was needed as part of this development.

Jee created a PIMS document to act as the main reference for the integrity management procedures throughout the lifetime of the pipeline. The PIMS document included detailed information on how the following points would be managed:

Safety systems and components

Personnel roles, responsibilities and interfaces

Basis of design and operations

Risk management

Mechanical and structural integrity

Emergency response and incident investigation

Documentation and reporting procedures

As an independent company, Jees engineers are able to give objective and impartial advice, offering a range of solutions to a variety of issues. Jee provided PIMS documentation that enabled the client to achieve regulatory approval to develop the project. Jees extensive track record in providing integrity management solutions to subsea partners facilitated the success of this project.


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Jee has the capability to help develop and maintain the PIMS, ensuring that experience gained during operation of the pipeline is captured and used to develop the PIMS further.

PIMS process

The IM process is shown below in Figure 2. During the plan phase a risk based assessment (RBA) is carried out to examine the threats to the pipeline system, and to later define and schedule integrity activities to mitigate the risks. These integrity activities are carried out and reported on in the implement phase of the process.

In the measure/assess phase the results from each IM activity is assessed and any further inspection or remedial work specified. The overall fitness for continued service is also assessed by considering all of the data gathered from the integrity activities and considering how they impact together.

When reviewing the data from all integrity mitigation activities to establish condition and assess anomalies, it is important to consider whether the inspection has provided enough data to make an accurate integrity assessment.

By analysing the historical trend of the integrity data when making an assessment, we are able to perform detailed analysis and assessment where required. This may flag up incidents of corrosion defect, dent, span, stability, etc. enabling the team to develop repair strategies where necessary and gather all integrity data to make an overall fitness for continued service assessment and document in an annual report.

The final phase of the process is improve. This is the feedback loop from the results of the integrity activities back into the risk assessment and plans. Taking account of modifications, lessons learned and new technology, enables optimisation of the IM program and reduce costs through review of inspection data. New or novel inspection technology can reduce inspection budgets. Carrying out periodic audits and reviews is also essential to ensure the system is being implemented correctly.

Figure 2. Integrity management process






It is essential to roll-out the integrity management system to every level that may be involved and be affected by it to ensure knowledge and engagement ensues. Within operators there are teams of subsea and pipeline engineers that specifically look at the integrity of the pipeline. However, positions like the Control Room Operator need to be aware of the management system, processes and activity to fully understand their role, the importance of IM and what they can do to mitigate risk.

Risk management

Jees dedicated team of engineers have extensive experience in every stage of the cyclic integrity management process and an in-depth understanding of how to effectively plan, budget and implement integrity management campaigns. Jee helps its clients enhance the efficiency of their assets and reduce operating costs, whilst ensuring unplanned shut-downs are avoided and there is minimal disruption to operations.

In order to do this it is essential failure modes of pipeline systems are understood. This knowledge can be obtained by assessing the risk of failure of each failure mode, leading to the understanding of the barriers, and the effectiveness of each barrier. Best practice to ensure that this occurs is to use the operators risk matrix in the process to ensure that risks are comparable to other company risks, and can be understood by the leadership team.

Defining the mitigations required to manage the risk through inspection, monitoring, testing, and maintenance helps take into account the effectiveness and limitations of the technique used to provide information about the risk. For example, the selection of a suitable inline inspection (ILI) tool for detecting the critical defect morphology cause by the corrosion threats to the pipeline is critical in achieving a successful ILI run.

Late lifeLifetime extension

When pipelines reach the end of their design life, engineering justification for extending the pipes life must be carried out if the pipeline is to continue to be operated. Good pipeline IM over the lifetime of the asset is an important factor for successful life extension and asset profitability. If the pipeline has not been well inspected and maintained then costly inspections and repairs might be necessary to justify the extension.

CASE STUDY Lifetime extension assessment

Jee was approached to carry out lifetime extension assessments (LTE) for nine pipelines situated in the North Sea. The pipelines were approaching the end of their design lives and the client wished to continue production.


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Jee completed the work in two stages starting with the main 30 oil export pipeline. Jee then used the lessons learnt and feedback from the client to continue to assess the remaining eight infield pipelines. The pipelines that were assessed comprised:

1 x oil export pipeline (30)

2 x oil import flowlines (6)

2 x condensate import flowlines (12 and 6)

2 x gas lift flowlines (6 and 2.5)

2 x service flowlines (4)

The first stage of the LTE was to assess the current integrity of the pipelines. The majority of the pipelines were well maintained, with some having been conservatively engineered at the design stage. The production pipelines were constructed of duplex stainless steel with excellent corrosion protection (CP) on the carbon steel spools. The gas lift and service pipelines were carbon steel containing dry gas and treated water respectively. No integrity concerns were found, other than a pipeline that had been laying unused filled with treated water.

The second stage was to verify the pipelines design against todays design codes and then determine the remnant life of the pipelines. The wall thickness calculations showed an adequate design and the stability study confirmed that if the pipelines were not buried that they would be unstable.

The 30 export pipeline had been pigged and existing ILI data could be used to assess the internal corrosion. The other pipelines were not piggable, and so corrosion was gauged on available corrosion coupons and ultrasonic testing (UT) inspection results on spools.

As with all LTEs, the outcome of the assessment depends heavily on the quantity and quality of the data. In this case, there were some gaps in operational data which meant that Jee had to assess the operational fatigue using a conservative approach with various assumptions, for example, a daily pressure fluctuation.

The conclusions of the LTE study showed that three pipelines could be granted an extended life, ranging from five years to 29 years. The remaining pipelines could not be granted an extended life at this stage due to the lack of inspection data. An external inspection of the riser contained within a sealed caisson was required to verify integrity. In other cases, it was the unknown status of internal corrosion on a flexible spoolpiece that was limiting the life extension options. Recommendations were given to inspect the riser and carry out UT inspections on sections of pipeline.

From this assessment, the client found out which of their pipelines were suitable for continued operation and the remedial measures required to ensure that the other pipelines remained fit for service. Jee made specific recommendations as part of this study and will continue to support the client to ensure that these pipelines continue to operate, ultimately saving money for the client.


Decommissioning

When installations are no longer required and are due to be decommissioned, many subsea facilities need to be removed or partially removed. Sometimes towards the end of life, understandably, investment in the facilities is reduced. This can lead to inadequate structural integrity for the chosen decommissioning method, potentially resulting in safety risks or having to develop a more costly method of removal. Therefore using good IM practices, while managing the decline of the pipeline system, can avoid this situation.

The AuthorGrant is an experienced chartered engineer who has been working in the oil and gas industry since 1994. He is the head of Jees integrity management discipline and has an in-depth knowledge of the field and its associated areas, including internal and external inspection. Working closely with a number of major operators, Grant provides technical support and pipeline technical authority services, advising on all aspects of design, construction, integrity, repair and the operation of pipeline systems.

Grant has completed a number of integrity management related projects, including creating riser inspection strategies, inspection tool and stuck pig contingency plans, corrosion management strategies and pipeline lifetime extension studies.






Whats Next?Did you know that this paper has been released in conjunction with the 3rd Annual Subsea Integrity Conference 2015, which returns to Houston TX this October 5-6?

Serving as Houstons foremost subsea hub, this meeting will define the future trajectory of the subsea market as it overcomes oil price uncertainty.

Ensure that you are the first to receive the SSIC 2015 brochure, including the very latest agenda scope and details on our brand new technical troubleshooting workshops and accredited training sessions

To stay ahead of the game, pre-order the full brochure today and well give you a regular run down of everything you need to know about this years world leading Subsea Integrity Conference.

With such a rich legacy of success, you can be sure that speaking, exhibition and sponsorship opportunities are already limited. Please do get in touch directly if youve any questions.

Jee will be hosting an all new Subsea Engineering Workshop at the Subsea Integrity Conference 2015. This exclusive training opportunity will give 25 engineers the tools they need to overcome a host of critical subsea challenges and develop their ability to manage the integrity of our most important assets.

Order the brochure here to receive all the latest meeting and workshop updates

2015 FC Business Intelligence

The information of this document was prepared by Upstream Intelligence (part of FC Business Intelligence) and its partners. Upstream Intelligence has no obligation to tell you when information in this document changes. Upstream Intelligence makes every effort to use reliable, comprehensible information, but we make no representation that it is accurate or complete. In no event shall Upstream Intelligence and its partners be liable for any damages, losses, expenses, loss of data or profit caused by the use of the material or contents of this document.

Upstream Intelligence grants you a license to make one free copy of the information contained herein for personal or non-commercial use only. Accordingly, no part of this document may be copied, performed in public, broadcast or adapted without Upstream Intelligences prior written permission.

Please contact Kerr Jeferies at [email protected] to request permission.


Kerr JeferiesSenior Industry Analyst Upstream Intelligence

+44 (0) 20 7375 7565

[email protected]

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Lessons Learned in Subsea Pipeline Integrity Management