Improper isolation of control line leads to Well Control Incident during intervention

IOGP Well Control Incident Lesson Sharing #24-2

After a failed attempt to install a wireline retrievable safety valve a leak was discovered at the well service panel.

The IOGP Wells Expert Committee/Well Control Incident Subcommittee believes that this incident description contains sufficient lessons to be shared with the industry. We further encourage the recipients of this lesson sharing to share it further within their organization.

What happened?:

Well intervention activities were ongoing. The program included the installation of a Wireline Retrievable Surface Controlled Sub-Surface Safety Valve (WRSSSV) in order to re-gain Down Hole Safety Valve (DHSV) integrity, where the Tubing Retrievable Subsurface Safety Valve (TRSSSV) had been failing to inflow test.

The WRSSSV was installed. Control line inflow test was then performed and not successful. WRSSSV was therefore retrieved. The intervention was then suspended waiting for the back-up WRSSSV to arrive at site for 2 days.

After the shift handover in the morning, the well service supervisor arrived on the platform to survey the worksite. The well service supervisor heard a faint hissing noise when walking around the platform and as he came closer to the well service rig panel, he could smell crude oil and observed hydrocarbons were coming out of the filling point for the hydraulic tank. He immediately went one level down and isolated the needle valves of the WRSSSV control line at the well head; the flow stopped.

What Went Wrong?:

• Lack of isolation (needle valves were not closed).
• Insufficient verification.
• No detailed procedure for suspending operation.
• Risk assessment does not highlight risk of communication between reservoir and surface through control line.
• Incomplete handover.

Corrective Actions and Recommendations:

• Reinforce TRA preparation (barriers aspects).
• Analyze incident and share the lesson learned with crews.

safety alert number: 363
IOGP Well Control Incident Lesson Sharing http://safetyzone.iogp.org/

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