IMCA: BSEE Anchor-handling causes damage to subsea equipment and triggers gas release

Description of Incident

The United States Bureau of Safety and Environmental Enforcement (BSEE) has published Safety Alert 508 on 30 September 2025.

What happened?

The United States Bureau of Safety and Environmental Enforcement (BSEE) has published Safety Alert 508 on 30 September 2025, relating to a gas-release

incident involving a dive support vessel (DSV) that was marking a pipeline ahead of a jack-up rig subsea well recompletion.

The DSV was recovering two bow anchors from the seafloor. As the DSV approached the subsea well site, the vessel moved down-current, and the No. 1 bow-anchor wire became entangled in the well. The DSV backed away,

but the wire remained snagged and multiple attempts to free it failed. During the final attempt, the wire caught the annulus-valve assembly, shearing several studs

and detaching the valve from the tubing spool. A strong gas plume surfaced. The DSV retreated about 600m, and an emergency response began. During

mobilization and execution of the emergency response, several critical preparation steps were overlooked.

To view this IMCA alert in full and download the Step Change in Safety Verifications of Learning and Feedback Form, click 'Download Alert' button above.