Incident during core drilling operation

A member has reported the following incident, noting that it is aware of similar incidents and wishes to bring details to the attention of the wider IMCA membership to assist in preventing future potential incidents of the same nature.

During a recent subsea core drilling operation, a diver was injured on deck of the diving support vessel whilst handling and preparing to lower a drill string with a loaded core barrel to a working diver.

Three divers were in the process of moving the drill string toward the stern of the vessel for over boarding and sending down to the diver carrying out the drilling operation. To facilitate this operation, the divers had connected the lift rigging, and, in concert with the diver operating the work winch on deck, two divers had moved the drill string with the loaded core barrel to the point where they were to up-end it to the vertical prior to running down to the diver below.

The diver holding the lower end of the drill string began to set the drill string down gently onto the deck, the upper end of the string being held by the deck work winch wire suspended from the ‘A’ frame at the stern of the vessel.

When the diver had lowered the end of the drill string so that it was lying at an angle of approximately 30 degrees from the horizontal, the inner core barrel that was not latched slid downwards inside the core barrel itself.

At this point the diver had changed his grip on the drill string from one that had been on the outside of the string to one where two fingers of his left hand were inside the end of drill string. The position of his fingers was such that when the inner core barrel slid to the end of the outer barrel and hit the inner lip where the diamond bit was attached, the tips of two fingers were amputated in a guillotine-type action.

The company involved has noted and has implemented the following actions:

  • a physical barrier in the form of a steel ‘end cap’ is to be fitted to the end of the drill string at all times when working with loaded core barrels;
  • all personnel were aware of the potential hazard, but more emphasis is to be placed on the actual procedures for the loading and unloading of core barrels, as well as the correct procedures for handling of drill string in general.