Pittsburgh, PA – LANXESS is adding to its extensive range of polyurethane (PU) systems for the oil and gas industry with a new prepolymer: Adiprene® Degrade 80C AQ90A. It can be used to manufacture elastomer components that can be deployed in temporary challenging applications and break down by themselves in warm (from 50 to 93ºC) and wet environments after a defined period of time.
This new prepolymer offers enormous opportunities, particularly in components such as underground fracking sealing elements and plugs that need to withstand considerable pressures in wellbores. It also can be used to make degradable films, seals or other elastomeric components through a low cost process. The components can carry out their hard work in wet environments at 80°C for six hours without any appreciable deterioration in their high-quality mechanical characteristics. Only then will the PU polymer start to break down. This process leads to the complete degradation of its mechanical material characteristics over just two to three days. And within less than three weeks, it will degrade entirely. Moreover, the degradation rate can be adjusted for specific wellbore conditions. “This means that after they have been used, the components do not need to be fetched out of the wellhead or destroyed there. This means less work and lower costs,” explained Dr. Matt Burdzy, expert in application development at the LANXESS Urethane Systems business unit.
Adiprene® Degrade 80C AQ90A is a polyester-based prepolymer made with the proprietary LANXESS Low Free (LF) technology and has a free isocyanate content of less than 0.1 percent by weight, ensuring that it meets extremely high standards of occupational health, safety and hygiene. This prepolymer – which currently has a pending patent – is notable for its low viscosity and high thermal stability up to 70°C, which makes it easy to handle. The low viscosity also makes it easier to manufacture components with more complex geometries. With regard to elastomer hardness, it can be adjusted to produce components from 75 to 90 shore A and which can be made at a high rate of productivity thanks to the short demolding times as explained by Dr. Burdzy: “Components can generally be demolded after around 30 minutes. Curing and post-curing can be carried out at relatively low temperatures of around 100°C, which helps to significantly cut the cost of processing.”
Along with great tensile properties, the high compressive strength above 5000 psi declines very little during use. “Test specimens stored for six hours at 80°C in a 3 percent aqueous potassium chloride solution had no cracks and still exhibited 70 percent of their original compressive strength. These characteristics in particular mean that our material is perfect for high-pressure applications,” explained Dr. Burdzy.
The new prepolymer has been developed with rubber-based elastomers in mind that are degradable in water and can be used in oil and gas extraction. Many of these systems do not lose their rubbery consistency when they break down. “Elastomers made from our new prepolymer, however, break down quickly, uniformly and reproducibly into many small water-soluble and insoluble fragments. The operator should then follow the waste treatment practices to ensure regulatory compliance,” said Dr. Burdzy. Another benefit of the PU elastomers is that they usually have longer mechanical service lives under the stresses of gas and oil extraction.
LANXESS Urethane Systems offers customers comprehensive support in the development of components made from the new prepolymer. “For example, we can adapt the combination of prepolymer and diamine curative to suit customer-specific requirements in order to achieve optimized performance in terms of material and processing characteristics,” added Dr. Burdzy.