Monitoring and inspection tools extend the service life of flexible risers

By Domenico Di Giambattista, Baker Hughes

Safely extending asset life becomes increasingly important to project economics as operators begin to weigh the cost of replacing ageing components. Risers are one of the most critical of these components, and many that are in service today are either at or beyond their original design life.

As enhanced recovery technologies have been employed and tiebacks from adjacent fields have been added to host production systems, risers have continued to work in harsh and dynamic deepwater environments where long-term fatigue loading accumulation has taken its toll. For owners working to keep assets in service to sustain production, extending the field life of risers is central to achieving that goal.

Over the past decade, it has been proven that riser service life can be extended safely, but as assets age, regulatory agencies are requiring more evidence that they can operate safely. Owners understand that they must provide proof that older risers are still fit for purpose, but it is challenging to demonstrate riser integrity using traditional inspection methods.

Remote monitoring and inspections

Historically, periodic inspections have been carried out with cameras and ROVs. While visual inspections are important, they are limited in their effectiveness because they only capture surface imperfections. And even when inspections identify a problem, there is no way to know how long the defect has existed. Without an in-depth understanding of the extent or criticality of the damage, the only way to prevent a potential failure is to take an extremely conservative approach to maintenance and repair. Normally, that means taking the riser out of service as expediently as possible to address the damage.

Today, a move toward more comprehensive inspections employing advanced monitoring solutions is changing the traditional approach to riser integrity management. New technologies are being used to continuously acquire accurate, real-time data across pipe architecture, making it possible to identify anomalies as they emerge so owners can make informed and judicious decisions about the type and extent of repairs needed to avoid unnecessary downtime and unplanned disruptions to production. 

For example, riser sheath issues can now be detected using electronic breach detection. An externally mounted tool identifies changes in applied stress in load bearing steel armoring wires and detects unloaded armor wires +/- 15 m from the mounting location. Identified anomalies can be monitored to ensure performance and safety are not compromised, allowing production to continue until the damage warrants attention.

By capturing integrity data in real time in a process that is fundamentally different and more thorough than conventional inspection methods, it is possible to better understand how imperfections impact performance and to determine when the time is right for maintenance and repairs.