Swellable packer technology is one of the few technologies that has been readily accepted by the industry in a very short period of time, about 15 years. Since its development, hundreds of thousands of swellable packers have been included in well designs. Initially, oil swellable packers were used to provide compartmentalization in horizontal wells that were drilled in thin oil reservoirs. In the spaces between the packers were slotted liners, sand screens, and/or inflow control devices (ICDs). Water swellable packers were also developed for non-cemented injector completions.

It did not take long, though, for the technology to be adopted in many other well designs, primarily the horizontal multi-stage fracture design. The use of swellable packers to test and/or ensure well integrity is also a typical application, where packers are used to complement cement jobs and increase the likelihood of cement providing long-term well integrity.

Many features of swellable technology make packers attractive for use in well designs. For one thing, they are very simple to implement. The packer is designed to work with the planned wellbore fluids. So, manipulating the tubulars or applying hydraulic pressure is not required to activate the packers. Instead the packers react to the wellbore fluids over time and eventually swell to fill the annular gap. The challenge in well design using packers is to get a proper balance between the swell rate in regards to installing the packer and the swell rate in regards to operating the well.

Obviously, the swell rate to install the packer cannot be too fast: any interference arising from the packer’s reaction with wellbore fluids would impede the installation. Yet, the time to seal cannot be so long as to delay production. In an overwhelming majority of the applications, these challenges can be managed, resulting in a successful use of the technology. However, in some instances well constraints create a slow swell environment, where the rate is too slow.

A slow swell environment is often associated with low temperature wellbores. At low temperatures, heavy or viscous oils typically pose a challenge for oil swellable packers. Often this challenge can be overcome by adjusting the elastomer chemistry. As with the oil swellable packer, the water swellable elastomer can face difficulties at low temperatures. But a larger contribution to a very slow water swell environment is the amount and type of dissolved minerals found in the completion fluids and formation waters; these dissolved minerals are usually Na, K, Ca, and Cl. The higher the mineral concentration or the salinity of the water, the slower the rate of swell.

Often at high temperatures, greater than 250 degrees Fahrenheit (121.1 degrees Celsius), the rate of swell is acceptable, but depending on the concentration of each dissolved element, the rate can still be unacceptably low. While the elastomer chemistry can be changed to adjust the oil swellable packer to slow swell environments, the water swell technology does not have that option.

To address this limitation imposed by slow swell conditions, TAM International developed TAM FastSwell® technology. This is a manufacturing approach to increase the rate of swell. This proven, patent-pending technology can be used with any of our swellable elastomer chemistries. It is simple in that the chemistry of the elastomer is the same. What the technology has added is a method to increase the surface area exposed to the wellbore fluids.

It does this without increasing the length of the packer or reducing its differential pressure rating. Through extensive research and testing, a method was developed to expose differing amounts of surface area to the fluids, which then manages the rate of swell. The novelty of this technology is that it offers several ways to do this, depending on the desired results and on the geometry of the packer. The figure shows a typical design that is used in multistage fracture wells where the swelling fluid can have a salinity of 25% or greater.

A common example would be the use of a 10 ppg brine for a completion fluid. With NaCl as the salt, this brine has about 26% salinity. The standard water swellable packer responding to this brine would create a 5000 psi seal in approximately 25 days. With the application of the TAM FastSwell® technology, this time can be reduced to 16 days, saving over a week’s time.

In the case of an oil swellable packer in contact with an oil having an API gravity of 22° at 120°F (48.9°C), the time to swell and seal is 39 days. Implementing the TAM FastSwell® technology reduces that to 18 days. As can be seen, the technology makes a significant difference. This allows swellable technology to be used in areas where it was once technically disqualified.

Since the technology is a manufacturing process, existing packer inventory can be used, which can bring a savings opportunity for companies with inventory they can no longer use due to changing well designs and conditions.

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