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A diving spread introduced new factors to consider when preparing a safety case, not least a new critical area with living quarters.

The challenge of providing risk analyses

Well-Safe Solutions was looking to install a saturated diving spread onto one of their rigs.

The diving capability is important in their decommissioning work, with saturation divers living in a pressurized environment while on board the rig.  

The planned installation was for a fully refurbished and upgraded D300 12-diver saturation diving system, complete with a bespoke fully electric submersible decompression chamber handling system and twin self-propelled hyperbaric lifeboats.

The system would ensure safe and effective handling of older hydraulic and manual tree systems.

Deploying a saturation diving system from the Well-Safe Guardian eliminates the need for a dive support vessel (DSV). Limiting the number of vessels in-field reduces simultaneous operations (SIMOPS) activity, removing the need for pre-work campaigns with other vessels.

This increase in the installation's scope of operations needed a renewed safety case submission to the Offshore Major Accident Regulator (OMAR), the UK authority responsible for regulating offshore major hazards.

Why Well-Safe Solutions chose Marex

With an established relationship of trust already in place, they turned to Marex to support them as a revision of the full suite of formal safety assessments was required.

We had already prepared the safety case for the Well-Safe Guardian and they knew they could rely on our 25 years of offshore expertise. That is what has equipped us with a wide range of risk-based methodologies, all of which give complete assurance of compliance.

How Marex responded

The installation of a diving spread introduced new factors to consider when preparing a safety case, not least a new critical area with living quarters. We needed to revise the existing risk analyses, including new potential hazards that had been introduced to the environment.

This look at the full suite of formal safety assessments, which included:

• fire and explosion analysis - in which the diving spread equipment was added to the list of primary targets against which the physical effects of the representative fire and explosion major accident events were evaluated using both quantitative and qualitative techniques
• escape, evacuation and rescue analysis - in which consideration was given to the emergency preparedness and emergency response arrangements in place for the divers in saturation and their support staff, as well as the impact upon existing EER arrangements. Hyperbaric lifeboats would be needed to allow evacuation of the divers who were under compression.
• bowtie major accident hazard analysis - in which a bowtie analysis was undertaken for the new major accident hazard of installation-based saturation diving operations.
• quantitative risk assessment - in which additional risk calculations were performed for the saturation divers accommodated on board the installation.

This allowed Well-Safe Solutions to ensure that all risks associated with the increase to the installation’s scope of operations had been identified and analysed through a robust risk management process and supported the subsequently successful safety case submission.

The results

Read more about how we originally supported the Well-Safe Guardian.

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