Casing/cementing/zonal isolation

25,000-psi 500°F Packer-Seal System

As operators continue to drill into deeper and more-extreme formations, the demand for technologies suited to these environments increases.

Source: Getty Images.

As operators continue to drill into deeper and more-extreme formations, the demand for technologies suited to these environments increases. Much effort has been invested across the industry to overcome obstacles in developing safe and reliable completion tools that are qualified for conditions in excess of 15,000 psi and 450°F. A technological milestone was set recently in packer-seal-system development―the first 25,000-psi, 500°F packer-seal system.


The criteria for designating fields as high-pressure/high-temperature (HP/HT) fields have changed over the years. Early on, HP/HT fields were those with pressures greater than 10,000 psi and temperatures higher than 300°F. During the last 20 years, the HP/HT designation changed to 15,000 psi and 350°F, an environment in which technical operational challenges have been mostly overcome. Other terms have come into use to designate new HP/HT thresholds. Extreme-HP/HT fields have pressures up to 20,000 psi and temperatures up to 450°F, and ultra-HP/HT fields have pressures up to 30,000 psi and temperatures up to 550°F.

High gas prices and the search for hydrocarbons in deeper formations are key drivers for development of new HP/HT completion technologies. Extreme-HP/HT wells are being drilled in the Gulf of Mexico, on the shelf and in deep water. Many of them have a total depth of more than 25,000 ft and exhibit reservoir pressures approaching 20,000 psi and temperatures exceeding 450°F. There is limited availability of specialized tools for these pressures and temperatures. In ultra-HP/HT environments, there are many technical difficulties that must be overcome, including seals and polymers, metallurgy, and test facilities.

Concept Design

The objective of this project was to design a sealing system for a packer for 7.625‑in., 51.2–52.8-lbm/ft casing. The sealing system must be rated to 25,000 psi at 500°F. Qualification testing was conducted with nitrogen to all rating-envelope points at 500°F with a cool down to 250°F. To enhance performance in as-rolled casing and ultra-HP/HT applications, two existing systems were considered for the new seal design. System A is rated to 15,000 psi and 350°F. System B is rated to 15,000 psi and 500°F. In addition, the System-A packer has been qualified for applications with grooved or poor conditions on the inside diameter (ID) of the casing.

The System-A packer, shown in Fig. 1, uses a three-piece, multiple-­hardness packing-element system that is set by compression and is contained by metal backup rings. The rubber packing elements push against the backup rings, causing them to expand to the casing ID. The higher the temperature, the more difficult it is to set this packing-­element system correctly. The higher temperatures cause the packing element to become soft, which then increases the difficulty of getting the backup rings to contact the casing ID before the rubber begins to extrude over them. Also, the higher the pressure, the thicker the backup rings must be, which makes them more difficult to expand. Therefore, at 25,000 psi and 500°F, the backup rings need to be thick but the rubber will be soft, making it difficult to expand the backup rings to the casing ID without the rubber extruding over them. However, this design performs well in irregular or grooved casing IDs. The tips of the backup rings are very thin, which allows them to conform to grooved and as-rolled casing IDs.

Fig. 1: System-A packer element in the run-in and set positions.


The System-B seal shown in Fig. 2 consists of a metal insert with rubber molded to the outside and an O-ring on the inside. The inside is tapered to match the taper on a swage. The seal and swage are pushed toward each other, causing the seal to expand to the casing ID. The rubber is bonded to the insert to prevent it from being removed by swabbing effects during pipe movement. Protrusions on the insert prevent the rubber from extruding. The System-B seal does not rely on the rubber to deploy the extrusion barriers; therefore, soft rubber can be used with higher temperatures. Also, System B appears to be able to hold higher pressure because the extrusion gap is smaller.

Fig. 2: System-B packer element in the run-in and set positions.


A new seal design combined the best aspects of Systems A and B. The thin metal backup profile from System A was coupled with the System-B seal. The combination resulted in an optimized design, shown in Fig. 3, which can be set at high temperatures and can hold high pressures with improved performance in ­irregular-ID casing.

Fig. 3: New packer-seal system in the run-in and set positions.

Material Characterization

Elastomer. Perfluoroelastomer (known as FFKM) was chosen as the rubber material because of its temperature and chemical resistance. FFKM has the highest temperature rating and best chemical resistance of known elastomers. The compound is stable in oil, amines, H2S, CO2, and zinc bromide. Also, the compound is stable up to 550°F and is Norsok‑qualified for explosive decompression.

Metallurgy. Nickel-alloy C-276 was chosen as the seal-material carrier because of its excellent ductility and corrosion and cracking resistance. Engineering stress and strain (from elastic to plastic) curves were determined through testing by a certified test laboratory.

Design Optimization. Finite-element analysis (FEA) was used for design optimization of the ultra-HP/HT packer-seal system. 2D axis-symmetrical nonlinear FEA was conducted to optimize the seal design. Five 2D nonlinear FEA models with varying temperatures and casing IDs were run.

  • Extrusion-barrier deployment
  • Maximum casing ID at 250°F
  • Maximum casing ID at 500°F
  • Minimum casing ID at 250°F
  • Minimum casing ID at 500°F

To achieve a viable design, the equivalent plastic strain in the metal insert and the maximum elastic/plastic strain in the seal were measured in all models. The equivalent plastic strain in the metal should not exceed the maximum allowable plastic strain, and the maximum elastic strain in the seal should not exceed the maximum allowable strain. The seal must set and withstand 25,000 psi above and below the packer with combined tensile and compressive loading without packing-element extrusion.
The process was repeated until an optimum seal design was achieved. Then, a 3D FEA model was developed to identify the minimum setting force. The 2D FEA model assumed that the casing ID was perfectly round, and the 3D FEA model considered an as-rolled casing-ID profile with as much as 0.070-in. deviation from nominal-ID dimensions.

Seal Manufacture

During the design-optimization process, manufacturing optimization was considered as a design objective. To make machining easier, the cavity on the metal insert was made as shallow and as wide as possible. The radius on the transition area also was made as large as possible. A bond between the FFKM seal material and the C-276 metal insert is required to prevent the seal material from being pulled off of the insert cavity by  high rates of fluid flow around the outside of the seal during deployment. The bond also is required to resist the seal material being pulled outward because of thermal expansion. Additionally, molding FFKM in complex shapes had not been performed previously, and therefore engineering and vendor collaboration was critical to the success of the seal construction.

Test Qualification

The test philosophy was for each new packer-seal system to be tested at worst-case conditions. The reliability of downhole completion equipment is influenced greatly by the ambient conditions of the equipment’s location. This new seal design was installed on a packer chassis, and qualification testing was conducted with nitrogen to all rating-envelope points at 500°F with a cool down to 250°F.

Test-Load Cases. Seven load cases were tested.

  • Rating-envelope Point 1—25,000-psi pressure below the seal with 240,000-lbf compression at 500°F
  • Rating-envelope Point 2—425,000-lbf tension at 500°F
  • Rating-envelope Point 3—25,000-psi pressure above the seal with 490,000-lbf tension at 500°F
  • Rating-envelope Point 4—25,000-psi pressure above the seal with 240,000-lbf tension at 500°F
  • Rating-envelope Point 5—425,000-lbf compression at 500°F
  • Temperature cycled from 500 to 250°F with 25,000-psi pressure below the seal and held for 1 hour, then heated back to 500°F
  • Rating-envelope Point 6—25,000-psi pressure below the seal with 365,000-lbf compression at 500°F

The pressure and load were held on the packer for 1 hour. The bubble tank was monitored for bubbles during the final 15 minutes. Fig. 4 shows the packer after testing. There was no damage to any of the packer components.

Fig. 4: Permanent packer after the test.


A permanent-packer-seal system was built to seal pressure from above and below the seal at 25,000 psi at 250°F and at 500°F. It is a big step into the ultra-HP/HT region, where the most potential exists for finding large amounts of resources for the global market.

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 159182, “A Completion-Technology Milestone—The First 25,000-psi 500°F Packer-Seal System,” by James Doane, Guijun Deng, SPE, and Scott Collins, SPE, Baker Hughes, prepared for the 2012 SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 8–10 October. The paper has not been peer reviewed.