Rig Compensator Lock-Up Risks and Mitigations
"Locked-to-Bottom" or "Pinned-to-Seabed" operations on floating drill rigs are inherently more risky than initial drilling activities.
Floating offshore drilling rigs, such as semi-submersible drilling rigs or drillships heave with every ocean swell. Heave compensation systems are built into floating rigs, typically either passive heave compensation, active heave compensation systems or a combination are used. Unfortunately these systems can fail. Upon failure if the riser or landing string is locked to bottom (also known as pinned to seabed), serious incidents can occur.
An important risk to assess is that of motion or heave compensator failure, where the consequence of failure may increased, eg during hydrocarbon flow-back operations.
ICON has provided a report with the aim of providing oil and gas operators and drilling contractors some guidance and clarity with regards to mitigating the risks associated with ‘locked-to-bottom’ or ‘pinned-to-seabed’ drilling and well operations. Among many other findings, the report concludes that:
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Traditional drilling rig motion compensators / heave compensators whether they be active compensation systems or passive compensation systems present a single point failure risk when a backup is not installed, and can lead to a major accident hazard during high risk, “locked-to-bottom" or "pinned-to-seabed” operations
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There is substantial evidence to show that rig compensator lock-up or compensatoin failure incidents occur relatively frequently
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Many operators are concluding that rig motion compensator lock-up / failure is a credible risk and a potential major accident event that must be mitigated
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To mitigate high consequence risks to ‘as low as reasonably practicable’, operators are more frequently opting to install independent back-up passive heave compensators to provide necessary redundancy
For more details, please contact us at [email protected].
The ICON ARTP Tension Frame range has been developed with significant operator input to suit various lock-up scenario’s and equipment configurations in order to mitigate heave compensator lock-up consequences.
See here for an overview of the ARTP range
