Handling explosive devices in wireline perforating isn’t just about following procedures—it’s about understanding the hidden dangers that come with downhole tools.

One mistake in handling trapped pressure nearly caused a serious injury on a job site.

The Setup: A Routine Gun Breakdown That Went Wrong

We had just completed a cased hole perforating job, and it was time to break down the shot gun assembly.

As usual, we followed the basic steps:

• Recovered the perforating guns from the well.
• Inspected for misfires or damage.
• Prepared to disassemble the toolstring.

Since we were short on crew that day, a non-QES worker stepped in to assist with breaking down the guns. That’s when things went wrong.

The Incident: Trapped Pressure Causes a Blowout

The worker was removing a port plug from the switch sub when suddenly—BOOM!

The port plug blew out of the sub at high speed, hitting him directly in the face.

At first, we didn’t understand what had happened. Then we realized: the sub had trapped pressure inside.

What Went Wrong?

• Non-QES personnel were handling explosive devices.
• Trapped pressure inside the gun had built up without visible signs.
• The port plug was removed before safely relieving pressure.

Had the pressure been higher, this could have resulted in serious or fatal injuries.

How We Fixed the Issue: Proper Handling of Explosive Devices

After this incident, we immediately revised our explosive handling procedures:

• Only QES personnel are allowed to handle explosive devices.
• Treat all recovered explosive tools as though they contain trapped pressure.
• Recognize signs of internal pressure:
  • Hissing or bubbling noises in shot holes or connections.
  • Difficult-to-unscrew connections.
  • Debris protruding from shot holes.
• Break down shot guns at the tandem instead of removing port plugs.
• If a sub with a port plug must be opened, secure it in a vice facing away from personnel.
• If trapped pressure is detected:
  • Move the gun away from personnel.
  • Let it sit for two hours, then recheck for pressure.
  • If pressure persists, notify management before proceeding.

Key Takeaways for Wireline Engineers

• Never let non-QES personnel handle explosive devices.
  • Explosives should only be handled by trained professionals.
• Assume every recovered perforating gun contains trapped pressure.
  • Even if it looks safe, internal pressure can still be present.
• Break down guns at the tandem, not by removing port plugs.
  • This reduces the risk of a sudden blowout.
• Follow proper trapped pressure mitigation procedures.
  • If a gun shows signs of pressure, isolate it and wait two hours before rechecking.

Final Thoughts: Safety Comes First in Perforating Operations

In wireline perforating, explosive handling mistakes can be deadly. That day, a small oversight resulted in a serious safety event, but it could have been much worse.

By treating every recovered explosive device as a potential hazard, we ensure that nobody gets hurt on the job.