Aqueous Degradable Polyurethane Elastomers for Oil & Gas Applications

A new class of patent pending aqueous degradable polyurethane elastomers have been developed that can be used in oil & gas exploration, drilling, completion and production where a degradable part is needed to provide a useful service life then quickly degrade when exposed to heat and water. This polyurethane technology eliminates the need for costly secondary operations such as milling, drilling or removing tools in downhole applications saving time and reducing cost. The degradable polyurethane is a low viscosity two-part heat cured elastomer that is easy to mold using low cost hot cast tooling techniques. The novel liquid polyurethane prepolymer can be formed into films, seals, sealing elements, tools, complex geometries or other aqueous degradable elastomeric components. The polymer is a tough tear resistant high strength elastomer with a tensile strength exceeding 5000 psi, elongation over 500%, and a 70% compression modulus greater than 13,000 psi. When integrated as a sealing element in a degradable hydraulic fracturing plug, the polyurethane is designed to be pumped down-hole, set and seal then degrade once the operation is complete. Once placed into service, the useful operating lifetime of this polyurethane chemistry is more than six hours when immersed in aqueous fluids at 80°C (176°F) (i.e. water or 3% potassium chloride). The elastomer can be compressed over 70% during its service-life providing a stable set of mechanical properties during use. The elastomer beings to fracture within two days and quickly degrades at 80°C (176°F) providing consistent and reliable results. Approximately 70% is completely water soluble while the remaining 30% fractures into small particles that can be easily removed or remain in the well. This paper reviews the development of the technology, applications, mechanical properties, service life, degradation profile and product life cycle.