Brad D. Wolaver

Identifying origins of and pathways for spring waters in a semiarid basin using He, Sr, and C isotopes: Cuatrociénegas Basin, Mexico

He, C, and Sr isotopes are used to infer spring sources in a water-stressed area. Spring-water origins and pathways in the Cuatrocienegas Basin are revealed by linking structure and geochemistry via regionally extensive fault networks. This study presents the first dissolved noble gas and He isotopic data from northeastern Mexico. Basement-involved faults with complex reactivation histories are important in northeastern Mexico tectonics and affect hydrogeologic systems. The importance of faults as conduits for northeastern Mexico volcanism is recognized, but connections between faulting and the hydrogeologic system have not been extensively investigated. This research tests the hypothesis that Cuatrocienegas Basin springs are divided into two general classes based upon discharge properties: (1) regional carbonate aquifer discharge (mesogenic) mixed with contributions from deeply sourced (endogenic) fluids containing 3 He and CO 2 from the mantle that ascend along basement-involved faults; and (2) carbonate aquifer discharge mixed with locally recharged (epigenic) mountain precipitation. Carbonate and/or evaporite dissolution is indicated by Ca-SO 4 hydrochemical facies. He isotopes range from 0.89 to 1.85 R A (R A is the 3 He/ 4 He of air, 1.4 × 10 −6 ) and have minimal 3 H, from which it is inferred that basement-involved faults permit degassing of mantle-derived He (to 23% of the total He) and CO 2 ( p CO 2 ≤ 10 >−1 atm). Mantle degassing is compatible with the thinned North American lithosphere, as shown in tomographic images. Sr isotopes in both Cuatrocienegas Basin springs and spring-deposited travertine ( 87 Sr/ 86 Sr = 0.707428–0.707468) indicate that carbonate rocks of the regional Cupido aquifer ( 87 Sr/ 86 Sr = 0.7072–0.7076) are the main source of Sr. Rock-water interactions with mafic volcanic rocks ( 87 Sr/ 86 Sr = 0.70333–0.70359) are not inferred to be an important process. Groundwater-dissolved inorganic C origins are modeled using major elements and C isotopes. C isotope data show that ∼30% ± 22% of CO 2 in spring water is derived from dissolution of aquifer carbonates (C carb = 30%), 24% ± 16% is from soil gas and other organic sources (C org = 24%), and 46% ± 33% is from deep sources [Cendo (endogenic crust and mantle) = 46%]. This study demonstrates the presence of mantle-derived 3 He and deeply sourced CO 2 that ascend along basement-penetrating faults and mix with Cupido aquifer groundwater before discharging in Cuatrocienegas Basin springs.

Structural and hydrogeologic evolution of the Putumayo basin and adjacent fold-thrust belt, Colombia

This multidisciplinary study evaluates the structural and hydrogeologic evolution of Cretaceous-age reservoirs in the Putumayo basin, Colombia. We focused on the Eastern Cordillera fold-thrust belt along the southern Garzon Massif. Many important hydrocarbon accumulations occurred regionally along the proximal foreland basin and frontal fold-thrust belt defining the eastern margin of the northern Andes. To understand why recent Putumayo basin and adjacent thrust belt exploration has resulted in a wide range of oil quality and limited economic discoveries, we reconstructed the structural evolution, timing of oil migration, and timing of groundwater infiltration by (1) assessing regional trends in formation water, oil, and reservoir properties; (2) quantifying the timing of hydrocarbon generation and migration relative to trap formation using (a) two-dimensional (2-D) and three-dimensional seismic data to define and constrain a restorable balanced cross section from the Upper Magdalena Valley to the Putumayo foreland and (b) coupled one-dimensional thermal basin modeling; (3) evaluating the potential roles of Mesozoic extensional faulting and Paleogene shortening in the generation and preservation of structural traps; and (4) assessing groundwater influx from the modern foothills into the reservoir using a 2-D numerical groundwater flow model. We suggest that four-way closure is limited in the study area, where most foreland-verging structures create three-way fault closures that do not effectively trap light hydrocarbons. In addition, east-dipping structures and a relatively large reservoir outcrop area provide water infiltration pathways. Groundwater modeling suggests reservoirs were water washed by 2–200 million pore volumes since Andean uplift. Finally, average reservoir temperatures are <80°C (<176°F), which further facilitated biodegradation.

Time Series Analysis of Energy Production and Associated Landscape Fragmentation in the Eagle Ford Shale Play

Spatio-temporal trends in infrastructure footprints, energy production, and landscape alteration were assessed for the Eagle Ford Shale of Texas. The period of analysis was over four 2-year periods (2006–2014). Analyses used high-resolution imagery, as well as pipeline data to map EF infrastructure. Landscape conditions from 2006 were used as baseline. Results indicate that infrastructure footprints varied from 94.5 km2 in 2008 to 225.0 km2 in 2014. By 2014, decreased land-use intensities (ratio of land alteration to energy production) were noted play-wide. Core-area alteration by period was highest (3331.6 km2) in 2008 at the onset of play development, and increased from 582.3 to 3913.9 km2 by 2014, though substantial revegetation of localized core areas was observed throughout the study (i.e., alteration improved in some areas and worsened in others). Land-use intensity in the eastern portion of the play was consistently lower than that in the western portion, while core alteration remained relatively constant east to west. Land alteration from pipeline construction was ~65 km2 for all time periods, except in 2010 when alteration was recorded at 47 km2. Percent of total alteration from well-pad construction increased from 27.3% in 2008 to 71.5% in 2014. The average number of wells per pad across all 27 counties increased from 1.15 to 1.7. This study presents a framework for mapping landscape alteration from oil and gas infrastructure development. However, the framework could be applied to other energy development programs, such as wind or solar fields, or any other regional infrastructure development program.Graphical abstractLandscape alteration caused by hydrocarbon pipeline installation in Val Verde County, Texas

Comparison of Recent Oil and Gas, Wind Energy, and Other Anthropogenic Landscape Alteration Factors in Texas Through 2014

Recent research assessed how hydrocarbon and wind energy expansion has altered the North American landscape. Less understood, however, is how this energy development compares to other anthropogenic land use changes. Texas leads U.S. hydrocarbon production and wind power generation and has a rapidly expanding population. Thus, for ~47% of Texas (~324,000 km2), we mapped the 2014 footprint of energy activities (~665,000 oil and gas wells, ~5700 wind turbines, ~237,000 km oil and gas pipelines, and ~2000 km electrical transmission lines). We compared the footprint of energy development to non-energy-related activities (agriculture, roads, urbanization) and found direct landscape alteration from all factors affects ~23% of the study area (~76,000 km2), led by agriculture (~16%; ~52,882 km2). Oil and gas activities altered <1% of the study area (2081 km2), with 838 km2 from pipelines and 1242 km2 from well pad construction—and that the median Eagle Ford well pad is 7.7 times larger than that in the Permian Basin (16,200 vs. 2100 m2). Wind energy occupied <0.01% (~24 km2), with ~14 km2 from turbine pads and ~10 km2 from power transmission lines. We found that edge effects of widely-distributed energy infrastructure caused more indirect landscape alteration than larger, more concentrated urbanization and agriculture. This study presents a novel technique to quantify and compare anthropogenic activities causing both direct and indirect landscape alteration. We illustrate this landscape-mapping framework in Texas for the Spot-tailed Earless Lizard (Holbrookia lacerata); however, the approach can be applied to a range of species in developing regions globally.

An Improved Approach for Forecasting Ecological Impacts from Future Drilling in Unconventional Shale Oil and Gas Plays

Directional well drilling and hydraulic fracturing has enabled energy production from previously inaccessible resources, but caused vegetation conversion and landscape fragmentation, often in relatively undisturbed habitats. We improve forecasts of future ecological impacts from unconventional oil and gas play developments using a new, more spatially-explicit approach. We applied an energy production outlook model, which used geologic and economic data from thousands of wells and three oil price scenarios, to map future drilling patterns and evaluate the spatial distribution of vegetation conversion and habitat impacts. We forecast where future well pad construction may be most intense, illustrating with an example from the Eagle Ford Shale Play of Texas. We also illustrate the ecological utility of this approach using the Spot-tailed Earless Lizard (Holbrookia lacerata) as the focal species, which historically occupied much of the Eagle Ford and awaits a federal decision for possible Endangered Species Act protection. We found that ~17,000–45,500 wells would be drilled 2017‒2045 resulting in vegetation conversion of ~26,485–70,623 ha (0.73–1.96% of pre-development vegetation), depending on price scenario (

Conservation status assessment of the endangered Mexican Blindcat, Prietella phreatophila

40–

Conservation Status of the Plains Spotted Skunk, Spilogale putorius interrupta, in Texas, with an Assessment of Genetic Variability in the Species

80/barrel). Grasslands and row crop habitats were most affected (2.30 and 2.82% areal vegetation reduction). Our approach improves forecasts of where and to what extent future energy development in unconventional plays may change land-use and ecosystem services, enabling natural resource managers to anticipate and direct on-the-ground conservation actions to places where they will most effectively mitigate ecological impacts of well pads and associated infrastructure.

Discovery of Endangered Mexican Blindcat, Prietella phreatophila, in Texas: Implications for International Groundwater Management and Evolution of the Regional Karst Aquifer Biota

content from an oral presentation July 15, 2017 at the annual Joint Meeting of Ichthyologists and Herpetologists in Austin, Texas, USA (http://conferences.k-state.edu/JMIH-Austin-2017/)

Greensites and brownsites: Implications for CO2 sequestration characterization, risk assessment, and monitoring

Robert C. Dowler, Department of Biology at Angelo State University is the corresponding author, robert dot dowler at angelo dot edu

Process-based soil gas leakage assessment at the Kerr Farm: Comparison of results to leakage proxies at ZERT and Mt. Etna

Paper presented July 15, 2017 at the annual Joint Meeting of Ichthyologists and Herpetologists in Austin, Texas, USA (http://conferences.k-state.edu/JMIH-Austin-2017/). The oral presentation of this content mentioned questions about the taxonomy and phylogenetic position of Prietella lundbergi and the only specimens attributed to P. lundbergi apart from the holotype. Since the presentation, we obtained high resolution CT scans of both the holotype and a specimen (TNHC 25767) from Cueva del Nacimiento del Rio Frio, not far north of the type locality. The anatomy revealed in those CT scans suggests that these specimens represent a single species, and that P. lundbergi is only remotely related to Prietella phreatophila, which would be consistent with results of Wilcox, T.P., F.J. Garcia de Leon, Dean A. Hendrickson, and D.M. Hillis. 2004. “Convergence among Cave Catfishes: Long-Branch Attraction and a Bayesian Relative Rates Test.” Molecular Phylogenetics and Evolution 31 (3): 1101–13. doi:10.1016/j.ympev.2003.11.006). Thus, further research is in progress by Hendrickson, Lundberg, Luckenbill and Arce that may result in taxonomic revision removing P. lundbergi from Prietella.