Oxidative breakers are used extensively to degrade the polymers used in oil and gas well hydraulic fracturing fluids. These oxidative breakers react extremely fast in most downhole environments and can degrade fracturing fluids at rates that are undesirable. To increase the stability of fracturing fluids, these oxidative breakers have been encapsulated, with various techniques, to delay the release of the breaker into the aqueous environment and cause a delayed break or degradation of the fracturing fluid. Historically, evaluation of the release rates has been accomplished by measuring the degree and rate of viscosity degradation in laboratory rheometers. These tests are very time consuming and somewhat subjective.
A new methodology is provided to characterize encapsulated oxidative breakers (EOB) using Thermogravimetric Analysis (TGA). The new approach is based on weight loss using constant or dynamic heating rates. The novel technique constitutes a powerful tool to characterize the product complementary to conventional laboratory tests which are time consuming.
This technique can be used to streamline the developmental process used in manufacturing these encapsulated oxidative breakers. It is also extremely beneficial for QA/QC of this type of product. The quality of these products can be determined in much less time and with better precision than conventional techniques. Relevant literature references have been identified and are included in the paper.