Gel Degradation Studies of Oxidative and Enzyme Breakers to Optimize Breaker Type and Concentration for Effective Break Profiles at Low and Medium Temperature Ranges

Abstract

Chemical breakers are used in hydraulic fracturing fluids to reduce the molecular weight of guar polymers which reduces fluid viscosity and facilitates the flowback of residual polymer providing rapid recovery of polymer from the proppant pack. Ineffective breakers or misapplication of breakers can result in screenouts or flowback of viscous fluids both of which can significantly decrease the well productivity.Breaker activity of low to medium temperature range oxidative and enzymatic breaker systems was evaluated, including ammonium persulfate, sodium persulfate, calcium and magnesium peroxides, and galactomannanase enzyme in linear gel fluids at temperatures from 75 o F-300 °F. Low temperature and high temperature viscometers were used to generate linear gelbreak curves with time at desired temperature. The amount of unbroken gel and residue, generated at different temperatures and breaker concentrations, was also determined using a "residue-after-break test (RAB)," for two oxidizers and one enzyme breaker, all used for similar temperature applications in the field.Viscosity measurement showed that reduction in the gel viscosity depends on both the breaker concentration and temperature. Also, increasing breaker concentration does not necessarily mean more reduction in viscosity. This paper provides a guideline of oxidative and enzyme breaker optimum use concentrations for specific temperatures in the form of breaker activity "S" curves. Enzyme breakers were found to provide a more homogeneous break and generate less residue compared to the oxidztive breakers in the resdiue-after-break (RAB) tests. IntroductionGuar is a naturally occuring polymer used as a gellant in hydraulic fracturing fluids to increase fluid viscosity. This viscosity is required to carry the porppant into the fractue after the frature has been created in order to keep it open when the pumping is stopped. Once the poppant is delivered into the fracture, the fluid viscosity needs to be reduced so that it is easy to flow back and clean-up the formation.

Improving Fracture Conductivity by Developing and Optimizing Channels within the Fracture Geometry: CFD Study

“…Enhancing crosslinker chemistry Ainley et al 1993, Putzig and St. Clair 2007, Sun and Qu 2011, and Legemah et al 2013 Enhancing breaker chemistry Brannon 1994, Sarwar et al 2011, Gunawan et al 2012, and Patil et al 2013 Fracture fluid additives Bang et al 2008, andKim et al 2015 Foamed fluids Hutchins and Miller 2005, Gupta et al 2005, Chen et al 2005, Friehauf and Sharma 2009, and Gupta and Carman 2011 Viscoelastic surfactant systems Samuel et al 1999, Gomaa et al 2011, and Gomaa et al 2015 Polymer chemistry Cramer et al 2004, and Gomaa et al 2014Proppant Technology Brannon et al 2004 These improvements contributed incrementally toward the goal of attaining the maximum theoretical conductivity that can be achieved in a homogeneous proppant pack.…”

Use of Hydrochloric Acid To Remove Filter-Cake Damage From Preformed Particle Gel During Conformance-Control Treatments

“…Their results, obtained from the Weicheng and Mazhai oil fields, show an improved injection profile and greater oil increase in the responding wells. Turner and Zahner (2009) conducted a field study in the Sockeye field, offshore California, on the applications of combining chromiumcrosslinked polyacrylamide gels and acid stimulation. Combining both treatments lowered water production and increased the oil rate in a manner that neither technique would have yielded on its own.…”

Chlorophyll: A Naturally Occurring Green Polymer Breaker for Hydraulic Fracturing

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