You can prep every sub, torque every joint, and verify every detonator, but sometimes it’s the smallest components that bring everything to a halt. This was one of those jobs—everything ready for plug setting during a wireline and perforating operation. Logging cable was good. Wireline truck dialed in. Pressure control equipment steady.
Then came the misfire.
We’d seen it before: a plug doesn’t set, no detonation, and just a subtle system short to clue us in. But this time, the cause wasn’t obvious until we tore down the firing head. That’s when we found it—a bent contact pin, pushed sideways just enough to ground out against the mass.
What Went Wrong with the Firing Head
The firing head was a compact design—one of the shorty styles commonly used for tight toolstrings in cased hole wireline work. It’s a favorite in the wireline services oil and gas sector for its versatility. But this model had a flaw: the contact pin had too much play. No insulator. No guide. And when the igniter nut pressed it even slightly to one side, it could short to the sub’s mass.
That’s what happened on this run. A bent pin, slight grounding, and the igniter never completed the circuit. The result? A misrun. No plug set. Wireline service companies live by run efficiency—and this one reminded us how fragile success can be.
The Fix: Adding Tubing to Insulate the Pin
After inspecting the firing head, we came up with a field fix: add a small piece of tubing over the pin. It’s a simple barrier that stops it from touching the sub even if bent during assembly. It’s now a required modification before any run involving this firing head design.
Until a permanent insulator is provided by the manufacturer, this tubing solution is our frontline defense. It’s not just about setting plugs—it’s about maintaining reliability in wireline perforating, formation evaluation, and cased hole logging jobs where downhole tools need to function flawlessly.
Wireline Logging and Lessons in Precision
In the wireline oilfield, no detail is too small. Whether you’re running a pipe caliper tool, performing a cement bond log, or managing perforation services, wireline equipment must be perfect—from the pin to the perf gun.
We’ve since built this best practice into our wireline control systems SOP. All crews are trained on how to inspect and modify these shorty firing heads before any job, especially in cased hole well services. This change is now part of our broader commitment to complete wireline solutions that include pre-job inspection of all tools, from eline services to production logging.
For New Hands Learning What Is Wireline in Oil and Gas
This isn’t just about a misrun. It’s about learning to think differently. For new engineers and techs coming up through wireline courses, this story is a reminder that not every failure is catastrophic—but every failure teaches.
When working with downhole pipe recovery tools, wireline perforating guns, or even prepping a horizontal wireline setup, remember: sometimes, one crooked pin can be the difference between a clean run and a return to surface with nothing accomplished.
Final Thought from the Field
Wireline service companies rise or fall on the strength of their details. From pressure control assemblies to wireline trucks, the difference between success and failure often comes down to whether someone double-checked the small stuff.
So if you’re running a shorty firing head soon—do yourself a favor. Insulate the pin. Because the next misfire won’t care how many perfect runs came before it.