Water-base fracturing fluids gelled with guar-based polymers are used for fluid loss control, viscosity development, and proppant placement in hydraulic fracturing operations. These polymers must be subsequently degraded with breakers such as enzymes, oxidizing agents, or acid. Prevention of premature reaction of these additives with the fracturing fluid may be accomplished by encapsulation of these breakers, thereby providing a delayed release. Many aspects concerning selection, testing, design, and application of delayed release breakers have been investigated and are presented in this paper.

Laboratory testing has been done, including (1) methods of product preparation and corresponding release profiles, (2) viscosity degradation using delayed release breakers and conventional breakers, and (3) determination of breaker requirements. Fracture conductivity data are also presented to show the benefit of these materials to improve the results of a treatment. Case histories are presented to show results of the application of these materials.

You can access this article if you purchase or spend a download.