The Day a Bit of Debris Stopped a Detonator

Posted on by Crissa Fel Tawadan

There are jobs that teach you about tools, and then there are jobs that teach you about failure. This was one of those days—the kind that stays with you and ends up becoming part of your personal wireline safety SOP. It happened on what was supposed to be a straightforward cased hole well services run. We were out for a perforation well operation using a standard TCP assembly, and everything seemed set: the wireline truck was on site, pressure control equipment rigged, guns assembled and armed.

But things didn’t go as planned.

When the Top Gun Didn’t Fire

We’d made the descent and began filling the hole, pressuring up as usual. The top gun had the firing head placed above it, and as pressure built during pump down perforating, it was constantly hammered by the fluid. On surface, we waited for the expected detonation—and it never came.

What followed was an all-too-familiar routine in the wireline business: confirming misfire, running diagnostics, pulling the tools, and starting the forensic teardown. Every wireline engineer knows that feeling. You’re hoping it’s a simple electronics failure or connector issue. But this one was mechanical.

The shear pins hadn’t fully sheared. The firing pin hadn’t struck the detonator. And the culprit? A small but stubborn buildup of debris lodged between the shear ring and piston. That debris acted like a wedge, jamming everything up in the firing head.

Wireline Tech Lessons in the Real World

We later learned this wasn’t an isolated event. The positioning of the firing head at the top of the gun made it the first point of contact for every surge of fluid. Over time—and especially during aggressive pressure cycles—debris and sediment found its way into the assembly.

For any engineer working in wireline well logging or wireline perforating, especially in the cased hole logging service market, this kind of discovery reinforces the importance of continuous learning and adapting field procedures. No matter how reliable your wireline control systems or downhole tools might be, configuration can make or break a job.

A Simple Fix That Changed Everything

From that job forward, we adopted a new setup: placing the firing head below the top gun. That adjustment protected the shear ring assembly from being directly pumped against, minimizing debris ingress. It was a small tweak, but it represented a larger shift in how we think about rigging up tools for wireline and perforating jobs.

I’ve since shared this lesson in multiple wireline courses and toolbox talks, especially with newer techs just getting into the field. Whether you’re working with perforating guns, downhole pipe recovery tools, hole finders, or pipe caliper tools, every piece of your wireline equipment chain matters—and every mistake has a cost.

What It Taught Me About Wireline Logging

That misfire underscored the importance of staying vigilant, no matter how many successful runs you’ve done. In the world of wireline services—whether you’re with a wireline company, part of a larger oilfield services company, or working independently—the details are what keep operations safe and efficient.

We later used caliper logs to assess pipe integrity post-run, and I remember thinking: it’s ironic how a single piece of debris inside a firing head could shut down a perfectly good perforation services job. But that’s wireline—every run is a live lesson in well integrity, formation evaluation, and system design.

Key Takeaways for Wireline Service Providers:

  • In TCP and wireline perforating operations, tool configuration matters as much as tool quality

  • Avoid placing the firing head at the top of the gun in pump-down environments

  • Inspect shear rings and pistons closely for debris during teardown

  • Document and share failure points—what you learn might save someone else’s job or life

  • Use wireline tech and downhole cameras to evaluate failures in detail

  • Wireline training and oil field safety courses should include real-world failure analysis

Final Thoughts

If you’re part of the wireline services oil and gas sector—whether you’re in eline services, working with horizontal wireline, or supporting plug and abandon campaigns—this kind of field story is more than a memory. It’s a warning, a tip, and a lesson all in one.

So the next time you rig up that wireline unit or load your perforating gun, remember: debris doesn’t need a big invitation to shut down your entire job. Double-check your configuration. Stay ahead of the problem. And never stop learning.