A Spatial Evaluation of Groundwater Quality Salinity and Underground Injection Controlled Wells Activity in Texas
Tomlinson, Kelly Marie
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Uncertainty around the relationship between underground injection-controlled wells and groundwater quality has spurred conversations around the potential environmental and societal impacts oil extraction may have on potable water, soil and plant life. The nature of the chemicals and disposal processes of water used within underground injection-controlled, coupled with advancements in oil and gas technology, have called for a closer look at how fracturing and flowback fluid may be affecting the environment. In this dissertation, a spatial evaluation of the groundwater quality constitutes related to salinity and underground injection-controlled well operations was performed on the Permian Basin extents of the Ogallala aquifer during the sample years 2004 to 2016. The foundation for this research was an assessment of the spatial patterns of freely available in situ data on groundwater quality provided by the Texas Water Development Board and underground injection-controlled operations by the Texas Railroad Commission. The goal of this research is to provide a regional assessment of the interactions between dynamically changing underground injection-controlled operations and salinity groundwater quality constitutes. Groundwater quality constitute datasets chosen for analysis underwent exploratory data analysis, Empirical Bayesian Kriging interpolation, and non-parametric Mann-WhitneyWilcoxon statistical testing to measure data variation and significance of change across the study area and time. Relationships of underground injection-controlled well operations to salinity groundwater quality constitutes were evaluated using visual analysis and spatially constrained multivariate clustering. The analysis also explores the relationship of individual operational parameters, such as maximum fluid volume and pressure, to groundwater quality constitutes through cluster and outlier analysis and non-parametric Mann-Whitney-Wilcoxon testing to measure the magnitude of influence. To expand beyond the use of in situ data, an investigation of the application of salinity, vegetation, and moisture indices derived from Landsat imagery to explain regional variance in Total Dissolved Solids, an overall water quality indicator, was performed employing regression analysis. The research presented in this dissertation reveals a potential link between UIC operations disposal wells and increased salinity concentrations within the groundwater. Utilizing freely available secondary datasets, provided by the state of Texas, an assessment salinity focused groundwater quality constitutes and their relationship to UIC operations was explored. Results indicate that the southern region, comprised mainly of disposal well activity has seen rises in salinity groundwater constitute concentrations across the study period. Providing a regional and complete view at salinity groundwater quality and UIC operations, the research in this dissertation serves as a guideline for developing procedures on the environmental assessment of salinity around UIC operations and as a tool for operators to evaluate potential risks with new and existing development areas. The methods and techniques presented in this study are not specific to the region. Replicability to other basins with underground injection-controlled operations can be used to aide other researchers in determining localized impacts.