Perforating is one of those wireline operations where precision meets high risk. Whether it’s pump down perforating, cased hole perforation, or plug and perf, one wrong move can mean costly misfires—or worse, an unintentional detonation.

I remember one job where a simple wiring oversight nearly turned into a disaster.

The Setup: Standard Perforating Run

It was a routine cased hole wireline perforation job. We had Titan CF switches in our toolstring, set up to fire sequentially using a control fire switch system. These computer-controlled modules replace traditional positive/negative EB switches, allowing precise firing of each gun in sequence.

Everything was ready:

• Perforating guns assembled and capped.
• RF switches set to SHUNT for safety.
• Wiring double-checked on each gun.
• Titan VeriFire system used to verify continuity.

We were good to go.

Or so we thought.

The Warning Sign: Unexpected Readings

As the logging cable spooled out and the toolstring descended, we performed our final VeriFire check.

That’s when we noticed it.

One of the gun switch indicators failed to turn green on the verification panel.

At first, we assumed a loose ground connection—it’s a common issue in wireline perforating systems. But as we rechecked the ground wires and Scotch locks, we realized something wasn’t right.

The positive/negative selector switch on the control panel was showing a negative voltage spike—something that should never happen in a Titan CF system.

If we hadn’t caught it, we would have sent unintended negative voltage down the logging cable—potentially triggering an accidental detonation.

Finding the Root Cause: A Wiring Oversight

We pulled the string back up to investigate and found the problem:

• The blue wire from the gun switch was connected incorrectly.
• Instead of leading to the EBTW (through-wire pressure bulkhead), it was mistakenly Scotch-locked to the plug switch.
• This bypassed the intended firing sequence, creating a stray negative voltage pathway.

A small mistake—but in perforating, small mistakes can have catastrophic results.

We rewired the system, retested with VeriFire, and ensured proper grounding before proceeding. This extra 30 minutes of troubleshooting likely prevented a costly misfire or worse.

Key Takeaways for Wireline Engineers

This experience reinforced some critical lessons about wireline perforating and control fire safety:

• Always verify your wiring.
  • A single misplaced Scotch lock or reversed wire can create unintended voltage pathways.
• Grounding is everything.
  • Titan CF switches require at least two solid grounding points—check and sand all connection points.
• Test before you run in the hole.
  • Use a VeriFire system to confirm every gun switch and connection before committing to the perforation job.
• Never ignore an anomaly.
  • The negative voltage spike was a warning sign—had we ignored it, the consequences could have been serious.

Final Thoughts: Safety Over Speed

In wireline perforating, the pressure to execute quickly is always there. But a rushed job can be a dangerous job.

This was a routine operation that almost turned into an expensive mistake. Thanks to pre-run testing and a solid troubleshooting process, we caught the issue before it caused problems.

For every wireline engineer, perforation tech, and wireline service provider—remember: speed is secondary to safety.