What recent research tells us about improving downhole sealing performance
In plug-and-perf operations, the rubber packer is more than just a component, it’s the primary line of defense for zone isolation. If the seal isn’t strong or consistent enough, even small failures can result in poor frac stage performance, costly NPT, or pressure test failures that delay everything.
A recent study examined packer performance using 3D nonlinear finite element analysis (FEA), then validated the findings with real-world testing. At KC Seals, we don’t run FEA models in-house, but we do turn design insights like these into rubber elements that perform in the field. Here’s what we learned and how it translates to better completions.
The research team ran simulations on a variety of rubber packer designs, testing how small changes in geometry, specifically thickness and sub-thickness affected stress distribution and deformation. The stress maps and charts below show just how much the shape and dimensions of the rubber can impact sealing performance.
Deformation Contours – Varying Rubber Thickness
As thickness increases, the element deforms more efficiently, requiring less axial travel to achieve full radial expansion. This reduces load on your setting mechanisms and helps achieve a quicker seal.
Contact Stress Contours in the XY Plane
Thicker packers deliver higher and more uniform contact stress, improving sealing strength and lowering the risk of extrusion or bypass.
Contact Stress Along the Casing Wall
These plots show where contact stress builds and drops off. Thicker elements maintain pressure across a wider contact path, reducing the risk of low-stress “dead zones.”
Maximum Contact Stress vs. Total Deformation
This chart shows which configurations strike the right balance between seal strength and required deformation. 20 mm thickness emerged as the optimal point.
Effect of Sub-Thickness (Core) on Contact Stress
Changes in the core thickness had much less impact, giving engineers flexibility to adjust mandrel dimensions for strength or fit without compromising sealing performance.
| Design Feature | What the Study Found | What That Means for You |
|---|---|---|
| Rubber Thickness | Increasing thickness from 18 mm to 20 mm significantly boosted contact stress, helping achieve a tighter seal with less axial compression. | You get a more reliable seal without needing to increase the setting force. |
| Sub-Thickness (Core) | Had less impact on overall sealing stress. Optimal performance was around 13 mm. | Gives you flexibility to strengthen the mandrel without sacrificing seal performance. |
| Element Height | Shorter elements (around 70 mm) delivered more even contact stress and reduced energy required to set. | Easier to set, easier to mill out, and better overall sealing efficiency. |
| Rubber Hardness (IRHD) | Going from 70 to 80 IRHD dropped contact stress by about 15%. The sweet spot is around 70 IRHD. | Soft enough to conform, but tough enough to hold pressure, even in HPHT wells. |
To test their model, the researchers built a plug with the following spec:
20 mm thickness | 13 mm core | 70 mm height | 70 IRHD hardness
We’ve built our operations to give you flexibility, speed, and control—without sacrificing performance.
Designing a better rubber packer doesn’t require a simulation lab, just the right partner who understands how material, geometry, and field realities come together. At KC Seals, we take that knowledge and turn it into real parts that isolate better, set faster, and hold under pressure.
Got a sealing issue or just want to tweak an existing design? Send over your spec- we’ll review it, suggest improvements, and ship a first article before your next job even mobilizes.
Zheng, C., Zheng, X., Qin, J., Liu, P., Aibaibu, A. and Liu, Y., 2021. Nonlinear finite element analysis on the sealing performance of rubber packer for hydraulic fracturing. Journal of Petroleum Science and Engineering, 204, p.108691. https://doi.org/10.1016/j.jngse.2020.103711