It was supposed to be just another stage on a pump down perforating run. The wireline truck was in position, tools were dressed, and we were cruising through a multi-cluster frac job on a long horizontal well. The guns passed initial switch tests, plug was set, and everything looked green on the wireline control system.

But just before arming, we noticed an intermittent short—then an open—then a short again. The system was flickering between statuses. The voltages didn’t match the diagnostics. Something was clearly wrong, but we couldn’t pinpoint it from the surface.

We pulled the string back out, cracked open the guns, and that’s when we saw it: the through wire had been pinched and split where it met the loading tube. A clean slice of insulation was peeled back, and copper was grounding to the carrier wall.

A simple wiring mistake had shut down an entire perforation stage.

The Problem Hidden in the Build

It turns out the issue wasn’t with the perforating gun or the switch. It wasn’t the igniter. The problem came from how we had loaded the shot tube into the carrier. The tubing—meant to contain and protect the through wire—had bunched up near the entry point. As the loader inserted the shot tube, the tubing split and peeled the wire insulation like a banana.

The exposed copper was in direct contact with the metal gun body. That’s what caused the short to mass, which showed up as an erratic current spike on the switch test.

And it all came from poor loading technique.

Why This Happens in Cased Hole Wireline

In cased hole logging and wireline perforating, the pace is fast. Crews are often loading in tight quarters under time pressure, especially in high-volume cased hole well services. But when the through wire isn’t secured properly inside the carrier—when it’s allowed to move, shift, or bunch—it’s only a matter of time before that insulation gets damaged.

This is especially risky in:

• Long wireline perforating gun assemblies

• Complex firing head configurations

• Multi-stage perforation well sequences

• Remote pad sites with minimal supervision

One compromised wire can derail hours of prep and delay an entire frac schedule.

The Fix: Wire Loading SOP for Through-Wired Gunstrings

Following this incident, we overhauled how we prep and load through-wired gunstrings. We introduced a mandatory candy-cane wrap procedure and standardized tubing taping for all shot tubes.

These steps are now baked into our wireline logging SOPs and are reinforced in every wireline course we teach.

Through-Wire Loading Best Practice SOP

1. Candy-Cane Wrap All Tubing

• Use electrical tape to wrap the tubing in a spiral (candy-cane style) from top to bottom.

• This prevents the tubing from shifting during insertion and holds it flush against the shot tube.

2. Tape Every Primacord Segment

• Secure the primacord to the charge with at least one wrap of tape per charge.

• This ensures direct contact and prevents bounce or misalignment during run-in.

3. Inspect Through Wire at Field Level

• Before assembling guns, remove the shot tube and inspect the through wire visually.

• Look for kinks, exposed copper, or twisted pairs. If anything looks off, rewrap and rerun the tube.

4. Slow Load Shot Tubes to Prevent Pinch

• Insert the shot tube slowly and evenly into the carrier, watching for bunching.

• If resistance is felt, stop immediately and recheck wire path.

5. Log and Tag All Issues

• Any damage found must be recorded in the job prep sheet and reviewed with the crew.

• This promotes accountability and helps track patterns in misruns.

Why It Matters in Wireline Services Oil and Gas

In the competitive world of wireline services market, every delay ripples downstream. One shorted wire leads to:

• Lost perforation stage

• Additional rig-up and pressure control equipment cycling

• Client downtime and frustration

• Crew fatigue and job fatigue

These are the exact kinds of small but critical issues that wireline companies must control to stay competitive in the cased hole logging service market.

Building It into Our Wireline Courses

Today, this is a featured case study in our hands-on gun building and wireline tech courses. We show real photos of damaged wires, conduct taping drills, and simulate the same faults we saw in this job.

Trainees learn how to:

• Tape and route tubing correctly

• Spot early signs of wear or pinch

• Match switch test failures to physical causes

• Maintain consistency across all builds—especially in horizontal wireline runs

Applying This Best Practice Across Operations

We now use this technique on every job that involves:

• Wireline perforating gun strings

• Multi-stage plug and perf

• High-count cluster shots

• Deep wireline well logging or formation evaluation runs

• Precision depth correlation using caliper logs, CBL logs, or pipe caliper tools

Even production logging services now get full wrap-and-check treatment, since electronics and wire continuity are just as vital there.

Final Thoughts – Wireline Success Starts at the Tape

This wasn’t a catastrophic failure—but it was one of those preventable misruns that sticks with you. One that teaches you not to overlook the small stuff. In wireline, small stuff is what we’re made of.

The right tape, the right wrap, and the right check can keep your wireline tools, gunstrings, and wireline unit running smoothly—no surprises, no flickers, no wasted stages.