IOGP Well Control Incident Lesson Sharing

Release of wellbore gas during slickline operation resulting in well control incident.


During Slickline operations on a fixed rig, gas was released above the Slickline BOP. The lower master valve was closed in on the X-mas tree successfully shutting in the flow. The lack of pertinent planning and operations execution, along with an incorrect well status prior to operations, led to personnel risk exposure at the wellsite.

While rigging up the SAS riser and the Slickline BOP on the X-mas tree on of a well classified as non-eruptive after an eruptivity test, the tubing pressure raised suddenly from 0 to 800 psi. Gas was then released at the 50ft level above the BOP, despite the swab valve being closed. Slickline operators connected the PCE and closed the lower master valve on the X-mas tree. Operations were then suspended.

What Went Wrong?:

  • Inadequate planning and organization prior to programme execution.
  • Failure to take control of DHSV before rigging up.
  • Slickline work programme was incorrect for the planned operation due to being programmed on an inaccurate well status.
  • There was a clear communication and coordination breakdown between the disciplines of production & interventions operations teams

Corrective Actions and Recommendations:

  1. An up-to-date and correct well status must be known to both production and well intervention operations teams prior to any work being programmed or carried out on a well.
  2. All task specifications and slickline intervention programmes shall include correct well eruptivity, X-mas tree, & DHSV status.
  3. Slickline intervention programme to be modified to reinforce the control of the SSV & DHSV. This must be known and clear to the on-site slickline team prior to rigging up.


safety alert number: 311
IOGP Well Control Incident Lesson Sharing http://safetyzone.iogp.org/

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