You never forget the first time a perf gun fires at the wrong depth.

I was fresh on a new wireline unit, prepping for a multi-stage perforation well job in a tight formation. The job required precision from start to finish—horizontal wireline, cased hole wireline, multiple plugs, and a stacked gun system ready for a critical well perforation.

Everything was in order: the wireline truck was rigged up, pressure control equipment in place, logging cable spooled, and the crew briefed. But when the first stage went off… it didn’t hit the zone. The charge fired, alright—but about 10 feet off from where we planned. That wasn’t just bad wireline logging—that was an expensive mistake.

It didn’t take long to figure out the issue. The gun had been loaded correctly, but it wasn’t marked. No “TOP SHOT,” no “BOTTOM SHOT,” no labels to indicate where the actual charges began or ended. We’d flipped it upside down during rig-up without even realizing it.

That incident sparked a new non-negotiable rule in my operations: Every perforating gun assembly must be clearly marked before it leaves the shop. Painted rings, labeled shots, blank sections—everything. It’s a foundational step in providing complete wireline solutions and maintaining well integrity.

Now, every perf gun we use is labeled with:

• A painted ring and “TOP SHOT” marking aligned with the uppermost charge

• A painted ring and “BOTTOM SHOT” marking in line with the lowest scallop

• “BLANK” clearly written where there are no charges

• And all necessary shipping info like UN number, hazard class, and EX number for compliance

It may seem simple—just a bit of paint or marker—but in the world of cased hole logging, wireline and perforating, and horizontal stage work, that paint can mean the difference between a perfect stage and a costly fishing wire line operation.

In my wireline courses, I emphasize how these “small” things are often what separates professionals from crews constantly in recovery mode. Whether you’re doing pump down perforating, production logging, or perforation services in the wireline oilfield, your team needs to understand the full scope of wireline control systems, downhole tools, and gun string assembly procedures.

This is especially important as the wireline services oil and gas sector continues to expand. The cased hole logging service market is evolving fast, and expectations from wireline service companies are higher than ever. Whether you’re a wireline provider specializing in pipe recovery, cased hole well services, or high-pressure horizontal wireline completions, standardization is everything.

Our field today relies on advanced wireline technologies—from tracer tech and downhole cameras to digital caliper logs and formation evaluation systems—but no piece of equipment can compensate for human oversight when it comes to loading or marking a perforating gun.

So here’s my takeaway for anyone stepping into the wireline business or managing wireline units: Label your guns. Mark your shots. Double-check every assembly before it hits the logging cable.

And if you’re training new hands, don’t just tell them to mark it—show them why.