CAREER: A Study of Predominant Flow Mechanisms and Parameters Controlling Contaminant Migration in Fractured Heterogeneous Rocks

The research objective of this Faculty Early Career Development (CAREER) Program project is to investigate the effects of rock heterogeneities and flowing conditions on the mobility of pollutants in fractured permeable rocks. Forced mobilization and spontaneous migration of fluids in underground formations are severely impacted by the presence of fractures, which vastly dominate the overall conductivity of rocks. Throughout the years, fields like geo-environmental engineering, reservoir engineering, hydrology, and geothermal exploitation have been continuously challenged with difficulties associated with the study of fluid flow in fractured formations. The research plan structures a comprehensive five-year strategy to investigate flow mechanisms controlling the migration of contaminants in fractured rocks through the integration of advanced experimental and modeling methods. Because of the difficulties associated with the representation of fractures existing in permeable rocks, the current understanding of the physical phenomena concerning fluid flow in these systems is still limited for the vast variety of scenarios present in natural formations. The intellectual merit of the work resides in the investigation of the simultaneous influence of fracture structure, orientation, and rock heterogeneities (sedimentary layers) on the mobilization of contaminants in fractured rocks, and the relative importance of flow rate, gravity, and capillary forces on the effective displacement of pollutants. X-ray computed tomography will be used to characterize rock structures and the migration of contaminants during core flood experiments, and a two-phase pore network model will be constructed to simulate and extrapolate experimental observations. Results from this investigation are expected to advance the understanding of multiphase flow in fractured rocks, and help in the identification of sets of properties and conditions responsible for important macroscopic effects. The proposed investigation will address questions such as: (1) Does the distribution of immiscible fluids inside a fracture affect the exchange mechanisms with the adjacent rock?; (2) Which mechanisms control fluid exchange between the fractures and the adjacent permeable rock?; (3) Which conditions favor one displacement mechanism over another? (4) What are the implications for the prediction of fluid migration and remediation of contaminated sites? The educational component of this award has two goals: (1) To build scientific capacity through mentorship, including resident instruction, graduate and undergraduate advising, and involvement in diversity enhancement programs; and (2) To provide the technical expertise for the development and design of an interactive groundflow exhibit at the Carnegie Science Center in Pittsburgh, PA.

Results from this study will have important applications in areas of social impact such as hydrocarbon recovery processes, control migration and distribution of underground pollutants, storage of radioactive waste, and groundwater transport. The five-year career plan has been designed to conduct innovative high-impact research activities which will be disseminated and transformed into effective learning tools. The educational component of this CAREER plan is designed to engage a large group of individuals with diverse technical preparation and background through mentorship and guided research programs. An extended educational impact will be derived from the construction of an interactive groundflow exhibit that is expected to attract the interest of the general public through engaging educational experiences connecting science and technology to everyday life.