Elucidating Physicochemical Processes Affecting Transport Phenomena Resulting from Hydraulic Fracturing of Natural Gas Reservoirs

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1604314Miller, Cass T.The use of hydraulic fracturing has allowed for the extraction of natural gas from previously inaccessible sources; however, hydraulic fracturing has also raised concerns due to the potential for contamination from migration of fluids from injection sites. The objective of the proposed project is to improve understanding of the physicochemical processes associated with the transport of hydraulic fracturing fluids through porous media and fractured media. This approach will allow a more detailed assessment of the potential adverse effects to the environment.The PI will investigate the relationship between fluid composition and physical properties, sorption of hydraulic fracturing chemicals to solid media (i.e., proppants and shale), and the flow and transport of multicomponent, non-Newtonian fluids in porous and fractured media. Aqueous solutions of common fracturing chemicals will be characterized with respect to density and rheological properties. Batch tests will be conducted to measure the sorption of fracturing chemicals to relevant solid materials. Micro-models will be used to elucidate fluid flow characteristics on the pore/fracture scale. Flushing experiments will be conducted in one- and two-dimensional, homogeneous and heterogeneous systems. Experiments will investigate the pressure-flow rate relationship for non-Newtonian fracturing fluids with a range of fluid compositions, and the transport of individual species within the fluid. Rigorous theoretical models will be developed in conjunction with the experimental work using the thermodynamically constrained averaging theory framework. The experimental portion of the project will provide a comprehensive dataset at relevant temperatures and pressures regarding: (1) the effect of fluid composition on physical properties, (2) the sorption of hydraulic fracturing chemicals on relevant solid media, (3) the flow behavior of multicomponent, non-Newtonian fluids in realistic porous and fractured media systems, and, (4) dispersion of dissolved species in non-Newtonian fluids. The experimental work will be conducted in conjunction with modeling using the thermodynamically constrained averaging theory approach. This method will result in the development of a macroscale model that is consistent with thermodynamic principles, and which allows for explicit identification of subscale processes and relationships between variables of interest. The development of such a model will greatly improve upon the existing state of modeling such systems, direct further experimental and computational work, and provide a consistent framework with which to better probe the fundamental aspects of complex fluid behavior in porous media. The project will disseminate the finding of the research by developing a web site, holding public forums, and participation in the UNCs Institute for the Environment IDEA program. In addition, the PI will: (1) contributions to education through course content, student research, and science outreach; (2) participation of underrepresented researchers and linkages to minority recruitment programs; (3) broad dissemination of findings in environmental engineering, environmental chemistry, and contaminant hydrology journals; (4) digital archiving and dissemination of unique data sets and video images of experiments; and, (5) expanded ties with international collaborators that work on complementary aspects of multiphase systems. In addition, the physical processes and chemical components chosen for this study are common to environmental remediation applications and will improve understanding of all such systems.