In the world of wireline perforating, you’re always one step away from either flawless execution or a frustrating misrun. I’ve been on both sides of that line, but one incident made sure I’d never leave detonator checks to assumption again. This was a standard cased hole wireline operation—horizontal well, multi-stage plug-and-perf, classic pump down perforating setup. Nothing unusual. Until everything went sideways.
We ran the guns. The plug set. The first two guns fired clean. But then—nothing. The next gun didn’t go. And that one failure turned a high-efficiency run into a troubleshooting session that lasted hours.
When the Deto Checks Out… Until It Doesn’t
Back on surface, we tore the gunstring apart, one section at a time. Eventually, we found the culprit: a faulty detonator that had passed the surface deto tester—but still failed to fire under prepare fire current in the well.
What hit hard was that the switch tests at surface had been perfect. The toolstring looked great. The logging cable was verified. The wireline control systems were clean. The perforating gun sequence was programmed correctly. But none of that mattered because the deto—tested once—was assumed to be fine.
That day, we learned that not all deto testers are infallible—and neither is human assumption.
A Hidden Manufacturing Flaw
What made this case even more frustrating was that the detonator wasn’t burned out. It had a manufacturing flaw. Poor soldering left a short circuit bridge internally, which made the cap fail in one polarity and not the other.
Turns out, if we had flipped the leads during testing, we’d have caught it.
Since that day, we’ve revised our SOP and included this scenario in every wireline course we teach. Because if you’re running a perforation well with 200 shots in a wireline perforating gun, all it takes is one faulty cap to stop the show.
The Deto Testing SOP We Live By Now
To prevent any more misfires, our team now follows this detonator testing process before every cased hole logging or wireline and perforating job:
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Dual-Polarity Testing
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Always test detonators with both polarities—leads in one way, then reversed.
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If either test fails, the detonator is immediately red-tagged and moved to the remnant box.
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Batch Verification
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If multiple detos are from the same manufacturing lot, they’re tested twice and then randomly sample-tested again.
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Redundancy Over Speed
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Every string is checked by two people—gun builder and engineer. No single person clears a detonator for use.
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Tracking and Reporting
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We record which deto was used in each section of the string and maintain it for post-run troubleshooting.
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Why This Matters in the Wireline Services Market
This may sound like overkill, but it’s not. In the high-pressure, high-volume world of wireline services oil and gas, where precision in perforating systems defines well success, this kind of quality control is the foundation of performance.
Missing one stage in a multi-zone perforation job not only delays the frac—it reduces production, affects formation stimulation, and costs the wireline provider and oilfield services company thousands in wasted time and resources.
The wireline services market is competitive. If you’re going to stand out, it’s not just about the latest wireline technologies or sleek wireline trucks. It’s about mastering the small, often overlooked steps that lead to complete, successful wireline solutions.
Deto Discipline Is a Team Standard
Today, our crews know the drill. If you’re wiring up a gun, prepping for cement bond log runs, or setting up for production logging services, the deto check isn’t something you do at the end of a long gun build. It’s something you do with full attention, before things go in the hole.
We include this entire process in our wireline courses, not just as a best practice but as a real story. Because once a deto fails underground, it’s no longer a checklist item—it’s a recovery operation.
What Is Wireline in Oil and Gas Without Reliability?
If you’ve ever had to explain to a client why a stage didn’t fire, you know that wireline well logging is only as reliable as its weakest component. Whether you’re deploying pressure control equipment, checking hole finders, or logging depth on a caliper log, the system works only when every part does.
And yes, that includes the cap that most crews assume is good after one beep from a tester.
Final Shot – What This Taught Us
We’ve taken this experience and turned it into a standard. If you’re operating in cased hole well services, managing wireline trucks, or leading a crew in the wireline oilfield, this isn’t just a lesson—it’s a must-have protocol.
Train your crew to recognize the difference between a checklist and a safeguard. Teach the real-world risks of skipping deto verification. And when bringing in new techs, make sure they understand that firing a gun isn’t just flipping a switch—it’s about knowing that every single part downhole has been checked, tested, and verified twice.