How Switch Tests and Port Plugs Saved a Wireline Operation From Disaster

Posted on by Crissa Fel Tawadan

I’ve learned a lot in this business—some from experience, and some the hard way. Working in cased hole logging and wireline well logging, you don’t get many second chances when something goes wrong downhole. But the biggest lessons I’ve picked up came from the jobs where things almost went off the rails. And the more I apply these lessons, the more I see how important it is to share them across our wireline services oil and gas crews.

Let me walk you through a few moments that stuck with me—and might save you a misrun, a skipped stage, or worse.

When One Missed Switch Test Cost Us Hours

We were on a pump down perforating job, standard cased hole wireline setup. The engineer running the string skipped a few switch test points during the operation—just one at surface, another before equalization, and then straight to plug set. Boom. Misrun. The Selectronic switch failed, and we didn’t catch it until we hit the “Prepare Fire” command.

No one wants to rerun a 20,000 ft well just to fix what a 200 ft switch test could’ve caught.

Since then, our switch test protocol has been non-negotiable. Every run now includes checks:

  • At surface when wiring up the cablehead

  • Entering the lubricator (critical for wireline control systems and wireline pressure control equipment)

  • Post-equalization

  • At 200 ft in the well

  • Every 3000 ft in the vertical section

  • Before setting the plug

  • Prior to initiating any perforation service

These steps keep your wireline gun, perforating gun, and wireline perforating systems functioning as designed—avoiding hours of delay and the dreaded fishing wire line scenario.

The Day a Missing Port Plug Flooded a Gunstring

During another wireline and perforating job, a crew did a standard rebuild on the gunstring. Switch tests at surface checked out fine. But 200 ft into the hole, another test failed. When we pulled the string out, we discovered the culprit: a missing port plug. It had been removed during troubleshooting and never reinstalled.

The result? A flooded wireline perforating gun and a completely preventable failure.

Now, we double-check everything—especially during rebuilds. Gunstring verification includes:

  • All port plugs and brass hardware in place

  • Proper cablehead wiring and logging cable inspection

  • Wireline truck setup confirmation with tension and depth systems aligned

  • Full reinspection after any change in normal operating procedure

It’s a simple protocol that’s now embedded in my wireline courses because it prevents disaster. Whether you’re using standard cased hole solutions or working with advanced wireline technologies, attention to detail is your lifeline.

Skipped Stage on a Perforation Well

You’d think skipping an entire stage wouldn’t happen. But it did. Communication broke down between the frac van and our wireline truck. The company rep didn’t confirm the shoot sheet, TCP had supposedly handled stage 25, and our engineer ran stage 26. The mistake wasn’t discovered until the next day.

That single missed confirmation could have cost the client thousands.

So now, before every wireline perforating job:

  • The client must confirm stage and depth by signing the shoot sheet

  • For remote monitoring, two-way radio confirmation is mandatory

  • If verification is missing, we stop the job—no exceptions

In the fast-paced world of horizontal wireline operations, these kinds of protocols are more than just safety measures. They ensure our wireline services market maintains integrity and efficiency, especially when performing precision-dependent operations like production logging, cement bond logging (CBL log), and formation evaluation.

No Marker Joint? No Excuse.

One time, we worked with a client that opted out of installing a marker joint. That threw our correlation off during each run. Instead of making guesses, we adapted. We created a pseudo-marker by stripping a collar at ~30°, pulled a collar log to bump-up, and used that for correlation on subsequent runs. It wasn’t ideal, but it was effective.

This is why I always say: if you want complete wireline solutions, you need to train for flexibility.

Wireline is a world where downhole tools, wireline control systems, and pipe recovery tech intersect with human focus, precision, and communication. From wireline trucks to pressure control equipment, from cased hole logging service market demand to real-world perforating services—our field is one of high stakes and continuous learning.

If you’re working in wireline companies or building your own wireline business, these aren’t just best practices—they’re survival tools. That’s why I’ve created wireline courses based on real incidents, technical processes, and the lessons that keep your equipment, your clients, and your crews safe.

Stay sharp. Stay safe. Stay wired.