Frac Plug Forensics: Our Top 8 Takeaways From DarkVision’s Latest Report

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June 28, 2024
Austin, Texas

Like always, DarkVision delivers insights that mean big things for the oil and gas industry. This report, “Frac Plug Forensics: Post-Fracture Plug Failure Root Cause Analysis and the Subsequent Impact on Stimulation Performance” (Pehlke et al.), explores high-resolution acoustic imaging technology and its applications for measuring plug failure. It’s well worth a read for any operator.

That said, we also know you’re busy, and you may not have time to read a 31-page whitepaper from cover to cover. That’s why we’ve pulled out the most important nuggets of information for a fast and easy read. Here’s what we learned.

1. High-resolution acoustic imaging has measured nearly 300K perforations worldwide.

This industry-standard technology is used to assess wells in major basins around the world. It’s captured more than two billion axial images that have helped operators assess critical defects and localized obstructions.

Acoustic imaging also captures 3D data points to show plug sets in casing walls, allowing operators to see how well frac plugs isolate stages. This study is based on imagery from more than 12,000 plugs.

2. Imaging has taken plug failure analysis to the next level.

When a plug fails, operators usually run a root cause assessment that accounts for proppant pumping data, post-stimulation perf area growth analysis, and localized acoustic imaging. But when it comes to that last one, it’s even more helpful to compare current imaging with historical data from previous failures. 

This way, you don’t just understand why a single plug didn’t work. You can identify trends and see why multiple plugs might be failing in a specific area—for example, because of erosional casing wall loss, plug slippage, or even ball unseating—and come up with a plan to address that failure.

READ MORE: Why plug slippage happens: 4 causes to watch out for

3. Acoustic imaging can detect and measure plug setting.

Imaging can detect and measure indents in the casing caused by a plug’s buttons. Researchers conducted a lab study to confirm that imaging provides the same data as high-resolution laser scanning. Since this imaging data was proven to be reliable, operators can use casing indent measurements to determine whether a plug was properly set.

4. Dissolvable plugs fail 7x as often as other plug types.

The study found that 28.1% of dissolvable plugs fail—that’s almost one in three. In comparison, they found much lower results for composite (4.2%), hybrid (2.3%), and millable plugs (2.8%).

DarkVision concluded that the higher failure rate for dissolvables is “likely due to the additional operational and environmental variables that may prevent them from performing as designed relative to alternative plug types.” This could include stage stimulation delays that increase the plug’s time downhole. (We’d also add that dissolvables are more likely to fail because that’s what they’re designed to do.)

READ MORE: Why we changed our minds about dissolvable plugs

5. Plug failure impacts perforation area growth.

When plugs fail to maintain zonal isolation, perforations downhole from the target stage can grow more than the target and uphole stages. That’s because more proppant is coming into the perforation. Stages often have a heel side bias, so stages that are downhole of the failure will see much greater heel bias as well.

6. Failure risk increases with ovality.

According to DarkVision, “the percentage of plugs that fail increases as percent ovality increases.” They noted a 12.2% failure rate at <1% ovality and a 43.3% failure rate at >3% ovality. You’ll likely notice that a plug’s failure severity increases with ovality, too. That’s why it’s essential to target locations with low ovality before you set a plug.

READ MORE: See how the PurpleSeal™ plug performed at 5% ovality

7. Operating area doesn’t affect failure rate

If you’ve frac’d in different basins, you know downhole conditions can be wildly different when it comes to pressure, temperature, and water properties. That said, plug failure rates are similar in the Haynesville (11.9%) and Permian (12.2%) basins. The Montney and Duvernay basins have a slightly lower failure rate of 10%. This likely means plug manufacturers (like us) are providing products that are designed to work in a wide range of conditions.

8. Plug failure rates are dropping over time.

The severe failure rate for frac plugs, including full breaches and wall loss greater than 33%, has decreased since 2021. Dissolvable plug failures have dropped by 37% and composite plugs by 30.6%. As acoustic imaging technology keeps developing and operators get a better picture of what’s happening downhole, we expect this number to drop even further. 

Want to add the industry’s favorite frac plug to your completion? Contact us today and learn more about the PurpleSeal™ composite frac plug.

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