We’d made it through the first two stages without a hitch. The wireline truck was running smooth, the logging cable tension looked great, and the perforating guns were synced with the system like clockwork. Everything was lined up for another fast plug-and-perf cycle on a horizontal wireline job.

Then it happened.

We went to set the plug—dead. The system wouldn’t respond. The switch test showed a short. Not an open. Not a misfire. A short to mass.

The plug hadn’t set. The stage was officially a misrun.

And just like that, the schedule cracked open, the pressure ramped up, and the whole crew shifted from rhythm to recovery mode.

The Culprit? A Tiny Pin Without Insulation

Once we pulled the string and opened up the firing head, the problem was easy to spot—though hard to believe. The igniter contact pin had been bent sideways by the small nut on the top of the igniter. That movement pushed the pin into contact with the firing sub’s metal housing, grounding it out completely.

There was no insulator. Nothing to keep the pin from drifting sideways under pressure or vibration.

Just a small misalignment… and an entire perforation well stage was lost.

The Hidden Risk in Shorty Firing Heads

This wasn’t a freak accident—it’s a design vulnerability in shorty-style firing heads. The pins have a lot of play. If bumped during rig-up, assembly, or handling, they can shift. Without an insulator, any sideways pressure turns the pin into a grounding rod.

And since many firing heads lack tight internal tolerance control, this isn’t a one-off. It’s a pattern waiting to repeat itself across the cased hole wireline field.

The Solution: Tubing as a Temporary Insulator

We didn’t wait for a redesign—we fixed it ourselves.

From that job forward, we started rebuilding every shorty firing head with a small length of tubing fitted over the pin. This acts as an insulator, keeping the pin centered and protected from lateral force. If the igniter nut presses against it, the tubing takes the hit—preserving electrical integrity and avoiding a short.

And that small fix has now prevented dozens of potential misfires in our wireline services work.

Tubing Installation SOP for Shorty Firing Heads

1. Inspect the Pin for Lateral Play

• Before every run, check the pin movement.

• If it’s loose or offset, don’t proceed without insulation.

2. Cut Tubing to Fit

• Use heat-shrink or precision-cut plastic tubing that snugly fits over the pin.

• The tubing must extend far enough to protect the entire length that might contact the firing sub.

3. Verify Insulation with Multimeter

• Once installed, verify isolation from mass using a resistance check.

• This confirms no grounding before rig-up.

4. Re-inspect After Every Run

• If the firing head is reused, the tubing must be rechecked and replaced if worn.

5. Do Not Substitute with Improvised Materials

• Only use tubing rated for downhole heat and pressure.

• Improvised wraps or non-rated materials degrade quickly and can worsen the issue.

Why This Matters in the Wireline Services Oil and Gas Industry

In the fast-paced cased hole logging service market, where every minute on-site costs money and momentum, a single bad pin can:

• Delay multiple frac stages

• Require full fishing wire line retrieval if the plug sets but the guns misfire

• Trigger well integrity audits from clients

• Disrupt entire wireline perforating schedules

• Lead to misalignment in formation evaluation and cement bond reporting

This fix isn’t just about the pin. It’s about showing up with a system that works—every single time.

What We Teach Now in Our Wireline Courses

We’ve added this scenario to our wireline courses under firing head diagnostics and electrical integrity. We walk students through:

• How to inspect for pin flex or misalignment

• Proper insulation installation methods

• Common points of short in wireline control systems

• How misfires affect downstream data in production logging services, CBL logs, and perforation services

Hands-on labs now include mock builds using shorty heads and open circuits to simulate real-time troubleshooting.

Applying the Fix Across the Wireline Business

This tubing solution is now standard across our wireline service companies and is reinforced during:

• All gun building operations

• High-frequency pump down perforating

• Plug and abandon jobs where plug misfires cannot be tolerated

• Work involving high-stage count perforating systems

• Any jobs involving shorty-style or modular perforating guns

Whether you’re working in cased hole well services or prepping a tool for a formation evaluation, this simple tubing fix saves time, money, and reputation.

Final Thoughts – The Most Expensive Misruns Are the Smallest Fixes Ignored

It’s wild how something as small as a piece of tubing can decide whether your day ends in success or a rig-line tangle. But that’s wireline.

Because in wireline logging, what you don’t insulate can cost you the entire job.