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Use of exclusion zones in event of coil tubing unit failure

  • What happened?

    Coil tubing unit crew arrived on location to perform a foam cleanout process on a well.

    They established a 10 feet (3 metres) exclusion zone on the coil tubing reel side (non-operator side).

    While in operation, the Chiksan swivel bearing failed causing it to unscrew from the side of the tubing reel.

    The Chiksan swivel and pipe assembly ejected and traveled 70 feet (21 metres) landing outside the exclusion zone.

    No injuries occurred, and no personnel were on the non-operator side at the time of the event (but they were working on the operator side).

    A Chiksan swivel and pipe assembly landing outside the exclusion zone
  • Why did it happen?

    Coil tubing unit was being operated at 1600 psi. Pressure relief valve was set at 2000 psi.

    Coil tubing unit was designed with a Chiksan swivel assembly on both sides of unit – both pressurised during operations.

    An exclusion zone was not established on the operator side.  Crew believed only the non-operator side was pressurised because a high pressure hose was connected to the unit.

    The bearing failure was caused by dry material accumulation inside of the Chiksan swivel, due to lack of maintenance.

    No restraint system in place on the coil tubing unit to prevent the assembly from ejecting in the event of failure.

    A Chicksan swivel on a coil tubing unit attached to the side of a red vehicle.
  • What did they learn?

    If the coil tubing unit is equipped with Chiksan swivel assemblies on both sides, be aware that both sides are pressurised. Remove swivel and piping assembly on operator side if possible.

    Follow manufacturer specifications for maintenance and lubrication. Verify lubrication before operating.

    To prevent ejection in the event of failure, ensure engineered restraints are in place.

    Ensure exclusion zones are established for appropriate equipment.

    What learn - icon
  • Ask yourself or your crew

    What other actions could have been taken?

    If we had such a failure and someone was seriously hurt, what would be our key steps in response?

    How do we know when the system is pressurised on both sides?

    What do we take into consideration when establishing exclusion zones?

    How do we know that the equipment has been properly maintained and lubricated?

    Ask your crew - icon
Published on 07/06/19 2107 Views

While in operation, a Chiksan swivel bearing failed, causing it to unscrew from the side of the tubing reel. The swivel and pipe assembly ejected and traveled 70 feet (21 metres), landing outside the exclusion zone.