Degradable Thermoset Polymer Composite for Intervention-Less Downhole Tools

Abstract

Commercially available polymeric frac balls and other downhole tools made with polyglycolic acid (PGA), a thermoplastic, have severe application limitations owing to their low Tg of approximately 104°F as well as high cost. A thermoset polymer composite made from cyanate ester resin has been developed that exhibits hot-water degradability as well as excellent mechanical properties. This polymer composite demonstrates excellent potential for use in structural components of downhole tools for intervention-less operations. A degradable composite with cyanate ester resin with a glass transition temperature (Tg) of 536°F was prepared by adding inorganic fillers and glass fibers. A new process was developed to prepare a bulk molding compound from this composite that enabled fabrication of parts via compression molding. Molded parts were tested for their mechanical properties and for their degradability in water and brines. The composite with one quarter inch chopped glass fiber has a compressive strength of 41.88 ksi, tensile strength of 15.83 ksi, tensile modulus of 3.62 Msi and an elongation-at-break of 0.48%. Composite degradation occurs at 200°F and above, with a higher rate of degradation observed as the temperature increases.