In wireline, you don’t always know when something’s gone wrong—until you’re already past the point of no return. That was the case on this job, a typical pump down perforating run on a horizontal well. We had the wireline truck in place, the logging cable tensioned, and the gunstring assembled and checked.

The plug was set. Everything appeared to be working—until I hit the Prepare Fire command.

That’s when the short showed up.

The wireline control system flagged an error, and sure enough, the system showed a short at the firing head. At that point, we had no choice—we had to pull everything out and troubleshoot at surface. And when we did, the failure was exactly what we feared: a faulty switch.

But it wasn’t the switch that failed us. It was our process.

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When the Problem Was There—We Just Didn’t Look for It

Looking back, I only performed two switch tests during the run: one at surface after building the gunstring, and one while bumping up into the lubricator. I didn’t run a test after equalization, or while entering the well, or at the 200′ mark where we typically catch early faults. Why?

Because someone once said you could “burn out” the switch if you tested it too many times.

Turns out, that’s not just wrong—it’s dangerously wrong. And that bad habit cost us hours in unnecessary downtime.

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The Truth: You Can’t Burn a Switch with Testing

There is no limit to how many switch tests you can run.

This myth had been floating around—unverified—and it led to an entire perforation stage delay. If I had run a proper switch test at 200’, we could’ve seen the problem early, pulled up, and swapped the perforating gun string before reaching the plug setting depth.

That moment changed how I approach switch integrity on every run.

The Fix: Mandatory Multi-Point Switch Test SOP

We revised our standard operating procedure immediately. Every wireline engineer and JFE on our crew now follows a switch test protocol designed to verify electrical integrity from surface to shot.

Here’s the sequence we now run on every job:

Wireline Switch Test SOP – Field Execution

1. At Surface: Initial Assembly

• Test immediately after connecting the firing head, CCL, and logging cable.

• Verify continuity and look for opens/shorts before inserting into lubricator.

2. Lubricator Entry: Vertical Test

• Run a test with the string vertical to detect grounding caused by gravitational movement.

3. Post Equalization

• Always test again after pressure equalization to catch early electrical drift.

• Equalization movement can shift internal wires or contacts.

4. 200-Foot Test While Entering Well

• This is your best shot at catching a fault without having to pull thousands of feet back out.

• Don’t skip it. It’s a critical checkpoint.

5. Every 3,000 Feet in Vertical Section

• Once past 200’, run switch tests every 3,000’ during vertical descent.

• Not applicable during pump down in the horizontal section.

6. After Correlation / Pre-Kickoff

• Once you correlate to the marker joint, verify integrity again before kickoff.

• If no MJ exists, do this at your final depth checkpoint.

7. Final Test – Before Setting Plug (“Prepare Fire”)

• The last check before executing the run.

• A failure here means pulling the string back—but that’s still better than a misfire.

Why This Matters in the Cased Hole Logging Service Market

Cased hole wireline jobs are time-sensitive. Every run impacts multiple frac stages, and every misrun introduces costly delays. Faulty switches can cause:

• Missed perforation zones in perforation wells

• Electrical failures that complicate production logging services

• Lost depth integrity on cement bond logs (CBL logs) and formation evaluation

• Recovery runs requiring fishing wire line services and additional pressure control equipment

In a competitive wireline services oil and gas environment, missed switch tests can cost tens of thousands in lost rig time. That’s why wireline service companies need to bake this SOP into every job and every training module.

Training Wireline Crews the Right Way

We now teach this in all of our wireline courses—and we emphasize that switch test frequency is not optional. New hands learn how to:

• Run and read digital switch test diagnostics

• Match fault codes to actual component failures

• Spot false positives from grounding during string movement

• Build timing for switch tests into run-in-hole sequences

We also use real-world dump files from this incident to show how easily a single missed test can lead to full job failure.

Supporting the Wireline Business with Real Process

This updated process is now part of our field-prep SOP and used across:

• High-stage pump down perforating jobs

• Deep wireline well logging in horizontal wireline environments

• Plug and abandon runs that require multiple switches across tools

• Multigun wireline perforating gun assemblies with inline firing logic

• Tracer tech, CBL, and production logging deployments

We’ve even built it into our job briefing forms so crews don’t forget when and where to test.

Final Thoughts – Switch Tests Aren’t Optional, They’re Lifesavers

The biggest takeaway from that misrun? You’re only as good as the test you didn’t skip.

Had I tested at 200’, we would have seen the failure coming. We would’ve pulled the string, swapped out the switch, and saved hours of time—not to mention face in front of the client.