Over the last decade, hydraulic fracturing has gained momentum in the U.S., and advances in the application of fracturing techniques have led to a resurgence of domestic energy production primarily from shale. As of 2013, estimates put the total undeveloped technically recoverable resource (TRR) of shale oil and gas, including coalbed methane, remaining in discovered shale plays in the U.S. at 741.8 tcf of natural gas and 23.8 billion barrels of oil (BBO).1 Given the growing relevance of this application, gaining a better understanding of the chemical components of the fluids can help in evaluating their use and impact. The primary ingredients for any hydraulic fracturing formulation are water and sand, usually accounting for more than 99 wt%. To provide an effective aqueous medium for suspension and transportation of the proppants downhole, water is typically thickened using a rheology modifier or gelling agent. Various classes of polymers, including biopolymers (polysaccharides) and purely synthetic polymers, have served as rheology modifiers in hydraulic fracturing fluids. Polymers must impart excellent rheological performance and suspension capabilities by forming strong gel structures while still maintaining pseudoplastic behavior to eliminate energy losses when pumping the viscous material. The most commonly used polymer in the hydraulic fracturing industry today is guar gum. Although guar-based fluids are able to provide the desired rheological properties for certain applications, they can suffer from fluid instability and can cause irreparable formation damage. Emphasis in the industry has shifted towards focusing on new alternatives to guar, especially for high temperature applications, in which the mannose backbone of guar is chemically unstable leading to a significant loss in performance. New associative synthetic polymers have proved especially promising in lab testing and will be given special attention. This seminar will provide a general overview of the function, evaluation, and rheological requirements of polymers in hydraulic fracturing fluids as well as their desired temperature stability and salt tolerance properties. Investigating the rheology of synthetic polymers in formulated hydraulic fracturing fluids and at elevated temperatures (150-200°C) has proven their advantage over traditional biopolymers, as highlighted in this presentation. 1. Nangmenyi, G., “The U.S. market for fracking fluids”, BCC research, EGY121A, Feb 2014.

Development of advanced polymers for hydraulic fracturing applications

249th National Meeting (2015)

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