Geology Dissertations and Theses

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Characterizing Petrophysical Properties of Carbonate Rocks Using Nuclear Magnetic Resonance and Complex Conductivity
(University of Kansas, 2019-12-31) Zhang, Fan; Zhang, Chi; Rankey, Eugene C; Tsoflias, Georgios
Carbonate rocks are well known for their highly complex petrophysical behaviors due to their intrinsically heterogeneous pore geometry and wide range of pore sizes. As a result, both effective characterization of carbonate pore systems and the prediction of fluid transport in carbonate reservoirs, remains challenging. This thesis focuses on using nuclear magnetic resonance (NMR) and complex conductivity to quantify carbonate pore structure and gain insights into fluid flow and lithology of carbonate reservoir rocks at the core and log scales. In the laboratory study, integrated NMR and complex conductivity data are used to characterize porosity, pore size distribution, and surface area-to-pore volume ratio, in grainstones, packstones, and mudstones from carbonate reservoirs in Kansas. Carbonate samples with varying pore types and depositional texture are characterized according to NMR porosity, log-mean of transverse relaxation time (T2) value T2ML, real conductivity σ', and imaginary conductivity σ". Widely used petrophysical relationships derived from NMR and complex conductivity data also are assessed, and alternative relationships appropriate for carbonate samples at laboratory scale are proposed. Furthermore, to test the proposed petrophysical relationships at a larger spatial scale, and to exploit the potential of borehole NMR data, this study analyzes NMR well log data from Wellington, KS. This study focus on the uses of NMR longitudinal and transverse relaxation time ratio (T1/T2) in electrofacies characterization. Through multivariate analysis of a suite of logs (e.g., sonic slowness, photoelectric factor, etc.), the results show that T1/T2 ratio is uncorrelated with other logs which makes it a potentially independent indicator for rock typing. The data bear on the accuracy of predicted electrofacies using T1/T2 ratio, and how factors such as lithology and fluid could impact the T1/T2 ratio. Extending beyond experimental observations, this work assesses and proposes new electrical and NMR petrophysical models, analyzes the factors controlling the variation within NMR logging data, and harnesses the complete NMR logging information to improve carbonate reservoir characterization. This work demonstrates the potential of combining NMR and electrical methods to advance understandings of fluid distribution and fluid flow in complex carbonate reservoirs.
Stable Isotope Geochemistry and Paleohydrology of the Poison Strip Sandstone, Early Cretaceous, Eastern Utah
(University of Kansas, 2019-12-31) Robertson, Clay Henry; Ludvigson, Gregory; Stotler, Randy; Fowle, David
The Poison Strip Sandstone Member is a unique unit in the early Cretaceous Cedar Mountain Formation of eastern Utah. A previous chemostratigraphic study of the Poison Strip Sandstone at the Ruby Ranch Road (RRR) section east of Green River, Utah produced a noteworthy dataset with interesting δ18O results (Ludvigson et al., 2015). The Poison Strip at the type section of the Ruby Ranch Member contains poikilotopic calcite cements that yield δ18O values that range between -16 and -13.5‰ VPDB (Ludvigson et al, 2015). These isotopic values represent a major departure from the typical δ18O values of about -8‰ VPDB documented during earlier studies of the Cedar Mountain formation and have either major paleoclimatic or later diagenetic implications for the unit. Through detailed petrographic, diagenetic, and stable isotopic analysis, we were able to determine that that the atypical δ18O values produced from the poikilotopic calcite cements of the Poison Strip Sandstone are the result of deep burial diagenesis. The precipitation of poikilotopic calcite cements were likely influenced by petroleum migration through the basin and may have also been impacted by hydrothermal fluids. Preliminary temperature and depth estimates of 2 – 3km and 73 to 90° C were calculated from the intergranular volumes and isotopic data.
Evaluation of Seismicity Trends in Kansas to Determine Possible Source Mechanisms Using Focal Mechanism Inversion and Spectral Analysis
(University of Kansas, 2019-12-31) Intfen, John William; Miller, Richard D.; Walker, J. Douglas; Zhang, Chi
High b-value, proper stress orientation and low stress drop are three factors that support the suggestion that a majority of events in central Kansas are induced as a result of changes in pore pressure. Furthermore, stress orientation and seismic trends align with regional lineations interpreted from magnetic data. These linear trends are likely influencing seismicity in the northern part of the state and the feature that supports the suggestion that injection of wastewater in an area 90km away is influencing seismicity in Smith, Jewell and Republic counties in Kansas. Kansas seismicity started in 2014 and rapidly increased in frequency, culminating in the largest recorded earthquake in state history on November 12th, 2014. This size event led to a drastic increase in interest and therefore the number of seismic stations distributed in areas previously determined aseismic. This resulted in the discovery of new earthquake clusters located outside historically active seismic areas. The Kansas Geological Survey (KGS) deployed a temporary and permanent station array to significantly improve coverage offered by a temporary network installed by the United States Geological Survey in 2013. This enhanced KGS network along with other stations installed across the state revealed new clusters in Jewell and Saline County, areas that were considered seismically quiescent. The focus of this research is to explore the characteristics of seismic activity clustering in locations outside the high profile area in south-central Kansas with the most proliferate seismic activity (Harper and Sumner Counties). These focus areas include Reno, Salina, and Jewell Counties where new clusters of seismic activity have developed since 2016. These three areas are host to notable clusters and were chosen base on unique and historically inconsistent seismic activity. For each of the three study areas (Jewell, Saline, and Reno) four focal mechanism algorithms determined the focal sphere orientation of 95 events using 34 different stations and the maximum horizontal stress for each area was calculated using a Michael 1984 inversion. Stress orientations in iv Reno County are consistent with those calculated in Oklahoma but rotates almost 90ᵒ further north in Jewell County. Brune stress drop was calculated for 90 events in each of the three study areas to compare with stress drops calculated in the south portion of the state (Harper and Sumner counties) and across the Central United States. Low stress drops throughout the state are consistent with the range of stress drops found for induced events in Oklahoma (Hough, 2014; Sumy et al., 2014) and other parts of the Central United States (Boyd et al., 2017).
Geochemical Fingerprinting of Yellowstone Hotspot Track (YHT) Eruptions from Ash Beds in the Central United States
(University of Kansas, 2019-12-31) Graham, Maggie Anna; Moeller, Andreas; Ludvigson, Greg; McLean, Noah
Volcanic ash beds have been shown to be reliable stratigraphic marker beds because they can be radiometrically dated using magmatic minerals: e.g. zircon, sanidine, etc. This can be utilized in any region containing ash beds and can be especially helpful where beds are laterally discontinuous, such as in the Ogallala Formation in western Kansas and Nebraska and overlying Pliocene and Pleistocene strata. These contain abundant volcanic ashfall beds, but regional correlations of these have so far been limited, due to their non-continuous outcrops and complex stratigraphy. U-Pb dating of zircon by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) at The University of Kansas from several ash outcrops has confirmed the correlation of these ashes with Yellowstone hotspot track (YHT) eruptions. Volcanic glasses from individual eruptions exhibit unique geochemical signatures, therefore lending each eruption its own distinct geochemical fingerprint. This tephrochronological approach yields robust correlations between the ash beds in the Great Plains strata of Kansas and Nebraska and their YHT source eruptions. The YHT eruptions Lava Creek B (0.6 Ma) and Huckleberry Ridge (2.1 Ma) of the Yellowstone Plateau and the Ibex Hollow (11.93 Ma) eruption of the Bruneau-Jarbidge (10.5-12.7 Ma) eruptive center on the Snake River Plain have previously been correlated to ash beds in western and central Kansas as well as northeastern Nebraska by major and trace element concentrations. Ash samples were collected in Norton, Smith, Jewell, and Meade Counties in Kansas and the Ashfall Fossil Beds State Historical Park in northeastern Nebraska. Trace element data trends of the Norton and Smith county, KS ashes can be correlated to the Ibex Hollow eruption (11.93 Ma) of the Bruneau-Jarbidge YHT eruptive center when compared to published values. Trace elements in volcanic glass shards from an ash bed in Jewell county correlate to Lava Creek B (0.6 Ma). Samples from different locations in Meade County, KS can be correlated with Huckleberry Ridge (2.1 Ma) and Lava Creek B (0.63 Ma), respectively. The sample taken from the basal unit of the deposit in Ashfall Fossil Bed State Historical Park, NE correlates with the Ibex Hollow eruption of the Bruneau Jarbidge eruptive center. Utilizing single shard analysis to generate bivariate elemental plots, chemical trends, and multi-element correlation coefficients proved to be more useful for determining correlations as opposed to comparing average measured values to published average values. The insight from this research into the provenance of volcanic glass helps to further refine the understanding of dispersal of volcanic ash and other minerals from their associated eruptive centers, and the chronostratigraphy of High Plains, especially the Ogallala Formation. Research discussed here strives to demonstrate advantages in both processing time and overall analytical cost compared to traditional U-Pb techniques. This technique is also applicable to deposits that are too young to be reliably dated using U-Pb dating. The demonstrated high efficiency of the geochemical fingerprinting approach will allow researchers to have a denser coverage of the hundreds of ash deposits throughout the Central United States, and elsewhere, to improve stratigraphic correlations.
Measuring actinide partitioning in zircon to improve the 230Th correction for 206Pb/238U dates
(University of Kansas, 2019-12-31) Cocciadiferro, Ashley; McLean, Noah; Roberts, Jennifer; Möller, Andreas
The element Th, and its isotope 230Th, an intermediate daughter isotope in the 238U decay series, is often excluded relative to U from the mineral zircon during crystallization. Zircon is geochronologically important because it incorporates U, but when Th is excluded, a deviation from secular equilibrium occurs. The return to secular equilibrium, where the parent nuclide and intermediate daughter products have equal activities, results in a deficit of stable daughter 206Pb. This causes measured zircon 206Pb/238U dates to be up to ~109 ka too young, necessitating a correction for the initial 230Th deficit by comparing the Th/Uzircon to an estimated Th/Umelt and calculating a fractionation factor. For many Cenozoic zircon analyses, uncertainty in this factor makes up a majority of the uncertainty budget because existing Th-U partitioning studies of synthetic and natural samples are imprecise (e.g. Burnham and Berry, 2012; Luo and Ayers, 2009; Rubatto and Hermann, 2007). We have synthesized zircon from a range of temperatures (1200 to 1350ºC), melt compositions (basaltic andesite to andesite), and oxygen fugacities (QFM-4 to QFM+4), all doped with 500-1000 ppm U and Th. By analyzing whole crystals using isotopic dilution methods and high-spatial resolution SIMS analyses, we have reduced the uncertainty on DTh/DU to 1-5 %. With higher resolution, we found that DTh/DU generally decreases with fO2 and increases with temperature and melt composition. The variation in our datasets we attribute to the sector zoning that can be seen in cathodoluminescence (CL) images of our samples. Dark sectors generally had higher DTh/DU ratios than light sectors. We were able to sample light and dark sectors with EMPA and SIMS spots and observed that weighted mean DTh/DU of our ID-ICPMS analyses existed inside the range of the ratios found in light and dark sectors. Using these measurements, we demonstrate that trace element partitioning varies on a micron-scale in zircon, but that whole-crystal DTh/DU can be applied to natural samples by estimating the volume ratio of light dark sectors. These DTh/DU ratios can be used to calculate 230Th corrections for zircon grown under similar oxygen fugacities, melt compositions, and temperatures to improve analytical uncertainties on 206Pb/238U dates. These higher precision dates can then be used to resolve rapid geologic processes like incremental pluton assembly (e.g., Mills and Coleman, 2013) or better constrain timescales of mass extinction and biotic recovery (e.g., Schoene et al., 2015).
The codell sandstone (upper Cretaceous) of Kansas
(University of Kansas, 1962-05-31) McKellar, Tom R.
Stratigraphy and paleontology of the Eagle Ford formation of north and central Texas
(University of Kansas, 1931-05-31) Moreman, Walter L.
Physiography and geology of south-central Kansas
(University of Kansas, 1934-05-31) Courtier, William Henry
Exhumation and incision history of the Torngat Mountains, northern Labrador and Quebec, Canada, using apatite (U-Th)/He thermochronology
(University of Kansas, 2005-05-31) Centeno, Juan Pablo
Apatite (U-Th)/He thermochronological data provide new insights into the exhumation history of the Torngat Mountains, which are located in Ungava Peninsula, northern Labrador and Quebec, Canada. Latest Jurassic to earliest Cretaceous rifting resulted in crustal extension and opening of the Labrador Sea, causing westward tilting and exhumation of the Labrador continental margin. Post-rift erosion and incision led to the formation of significant topographic relief in the Torngat Mountains. Thermal modeling of apatite (U-Th)/He thermochronological data from a vertical sample transect indicates that rapid cooling starting at ~140-150 Ma, which closely coincides in age with independent geological evidence for initial rifting in the area. Apatite (U-Th)/He ages along an E-W transect, which was collected perpendicular to the Torngat Mountains and the Labrador coast, record differential extensional and erosional exhumation diminishing westwards towards the interior of Ungava Peninsula. Ages near the Labrador coastline are as young as ~ 78 Ma and are significantly younger than the timing of onset of initial rifting (~140-150 Ma); this suggests significant amounts (~1-2 km) of post-rift erosion and incision along the eastern continental margin of the Labrador Sea. West of the Torngat Mountains, along the E-W transect, apatite (U-Th)/He ages also show evidence of substantial post-rift erosion likely related to Mesozoic and Tertiary fluvial erosion or to Pleistocene continental glaciation. Two constant-elevation N-S transects collected parallel to the Labrador coast show apatite (U-Th)/He ages that mimic the larger scale topographic features of the area, such as major rivers and fiords, indicating a deflection of shallow crustal isotherms due to post-rift development of highamplitude topography. Additional numerical modeling is required to refine the timing and spatial magnitude of post-rift erosion in more detail.
The Cherokee of Southeastern Kansas
(University of Kansas, 1936-05-01) Abernathy, George Elmer
The object of this report is to record the results of a detailed survey of the Cherokee shale. The different members of the Cherokee are described so that they may be recognized and differentiated from each other. Some of these members are correlated with recognized members of the Cherokee in the adjacent areas of Missouri and Oklahoma. The economic geology or the Cherokee within the area of the outcrop and its geologic history are summarized.
Advective Transport: Importance to Groundwater Remediation and Illustration of Basic Transport Concepts to Introductory Audiences
(University of Kansas, 2019-05-31) Banks, Andrew Todd; Hill, Mary C; Devlin, Rick F; Stotler, Randy
Developing effective transport models with meaningful results requires a solid understanding of transport concepts and the underlying mechanics the model, and how data can be best integrated into the model. This research makes contribution to each of these three requirements: concept education, understanding simulated mechanics, and integrating data into models. (1) How can groundwater flow and transport processes be well communicated to introductory audiences, while providing a foundation for complex model development and interpretation? The first part of this work presents GroundWaterTutor, a freely available computer module for groundwater education. GroundWaterTutor provides a simple, interactive environment for learning how key system characteristics affect hydraulic heads and the flow of tracer particles. The software was developed using MATLAB in conjunction with MODFLOW 2005 and MODPATH 6, and thus provides a solid foundation from which students can expand to simulating more complex situations. GroundWaterTutor is distributed as a set of freely available standalone executables. (2) How do simulated advection interact with dispersion in groundwater remediation simulations? This question is addressed in the context of the following research question: How well do advection-based metrics for assessing the effectiveness of active in situ groundwater remediation strategies work? Results are important to developing an efficient optimization framework for in-situ active remediation systems. (3) Can heteroscedastic data, like concentration data, be integrated into models, such as groundwater models, without log-transformations, which make results hard for many users to interpret? Here the use of error-based weighting methods are investigated, which provide more intuitive regression models than log-transformation in the presence of highly variable (e.g. heteroscedastic) data. For this problem, log-transformation produced good model fit, while the error-based weighting formulations tested worked poorly.
Timing and drivers of exhumation in the hinterland of the North American Cordillera from detrital zircon U-Pb and (U-Th)/He double-dating
(University of Kansas, 2019-12-31) Graham, Kathleen; Bidgoli, Tandis; Walker, J. Douglas; Moeller, Andreas
The late Cretaceous to early Cenozoic hinterland of the North American Cordillera is widely recognized as an orogenic plateau. Although most studies suggest that this highland was in place by the Eocene, the timing and underlying drivers of the plateau’s development and eventual demise are not well known. To better understand this evolving orogenic system, this study focuses on constraining the age, provenance, and depositional lag-time of Eocene sediments along the California continental margin. These sandstones were sourced, in large part, from the western margin of the highland and may therefore offer clues to its development. A total of 2,163 new detrital zircon U-Pb ages were obtained from 16 samples to confirm the published provenance of the sandstones and/or recover new grain-age populations. The U-Pb ages reveal the major sources for zircons: Permian-Triassic, Jurassic, and Cretaceous arc rocks, the Paleo- and Mesoproterozoic Mojave and Mogollon Highlands, and the Idaho Batholith/Challis Volcanic Center. Samples north of the Transverse Ranges display a stronger arc signature, while samples south of them were sourced from the Mojave and Mogollon Highlands. 159 new (U-Th)/He ages obtained from a subset of the zircons analyzed from each sample, record either one or two significant age peaks. The majority of samples have a strong latest Cretaceous cooling signature; however, most samples also record Eocene cooling. The six samples from the Santa Ynez Mountains and from Vacaville area contain cooling ages that likely reflect post-depositional resetting of samples and are not considered for further interpretation. Observations from the (U-Th)/He dates suggests that most samples with probable sources inboard of the Sierra Nevada record short lag-times, indicating little to no delay between source exhumation and sediment deposition. Overall, the (U-Th)/He dates suggest that hinterland sediment source regions were affected by major pulses of exhumation in the late Cretaceous and the Paleocene to Eocene. Late Cretaceous exhumation fits well with the timing of Sevier deformation, but rapid exhumation in the Eocene is not readily explained by the tectonic framework of the region. We hypothesize that Laramide-related tectonism in combination with rapid erosion due to changing climate are responsible for this Eocene exhumation.
Seismic attribute analysis and CO2 monitoring within the Mississippian reservoir, Wellington field, Sumner County, Kansas
(University of Kansas, 2019-05-31) Haga, Lauren; Tsoflias, George; Black, Ross; Walton, Anthony
The Mississippian reservoirs are prolific hydrocarbon producers in the mid-continent of the United States but are challenging to image seismically due to their high heterogeneity and thicknesses typically below seismic resolution. In 2016, the Kansas Geological Survey (KGS) conducted a pilot study in the Mississippian chert reservoir at Wellington field, Sumner County, Kansas to determine the feasibility of injecting CO2 for enhanced oil recovery (EOR) and geologic storage of CO2 in this geological environment. This study evaluates the use of seismic methods for imaging the injected CO2 in the Mississippian reservoir. Time-lapse seismic comparison of an arbitrary line extracted from the pre-injection 3-D seismic survey and a coincident post-injection 2-D line proved ineffective due to differences between a 3-D volume and 2-D profile imaging. Therefore, imaging the CO2 centered on analysis of the post-injection 2-D seismic line characteristics both near to and far from the injection well, KGS #2-32, where CO2 saturation varied from 50% to 0% respectively. Fluid substitution modeling was used to evaluate Mississippian reservoir acoustic property changes due to CO2 saturation changes. CO2 saturation levels of 10%, 25%, and 50% displayed a decrease (larger absolute value) in normal-incidence acoustic impedance of up to 2.4%, 6.1%, and 13.3% with increasing CO2 saturation, respectively. Amplitude Variation with Offset (AVO) analysis of the post-injection 2-D seismic line evaluated the amplitude response at seismic gathers near to and far from the injection well. The majority of the CDP’s (including CDP 203230 – location of KGS #2-32) exhibit significant scatter but an overall decrease in amplitude magnitude with offset is present indicating a Class I AVO response of the Mississippian reservoir. Noise identified in the gathers was suppressed using f-k filtering; however, intercept-gradient crossplots and gradient curves throughout the seismic line were too scattered to reliably identify changes in CO2 saturation. Three factors contributed to the negative result: 1) Class I AVO increasing impedance, high matrix incompressibility of carbonate reservoirs make fluid detection challenging, 2) a relatively small amount of CO2 (20,000 tons) was injected in the reservoir and 3) poor near surface conditions during data acquisition resulted in noisy seismic data. Although these challenges made it difficult to image the injected CO2 in the field, fluid substitution modeling suggests a decrease in normal-incidence acoustic impedance with increasing CO2 saturation, which may yield detectable changes in seismic data under favorable field conditions.
A Data-driven Approach for Mapping Grasslands at a Regional Scale
(University of Kansas, 2019-05-31) Peterson, Dana
The goal of this research was to use a data-driven approach to develop a regional scale grassland mapping protocol with the following objectives. First, identify and characterize the spatial distribution of grassland types and land use across Kansas as well as the static or dynamic nature of grasslands over time using multi-year U.S. Department of Agriculture (USDA) Farm Service Agency (FSA) 578 data. Second, evaluate the spectral separability of four hierarchies of grassland types and land use using FSA 578 data, multi-seasonal Landsat 8 spectral bands, Landsat 8 Normalized Difference Vegetation Index (NDVI) data, and Moderate Resolution Imaging Spectrometer (MODIS) NDVI time series. Third, determine the optimal data combination, and the appropriate thematic resolution, for mapping grassland type by evaluating the modeling performance of the Random Forest (RF) classifier. A county-level analysis of the multi-year FSA 578 data found that the data were not all-inclusive of total grasslands across Kansas, but were sufficient to illustrate regional trends in grassland type, land use, and field size. Eastern Kansas was found to be more diverse in grassland type, more variable in land use, and contained a high number of smaller fields. Conversely, western Kansas consisted of larger fields that were primarily grazed native grasslands and land enrolled in the Conservation Reserve Program (CRP). These results indicate a more complex grassland landscape to map in eastern Kansas, while also providing guidance for training sample distributions for image classification. Jeffries-Matusita (JM) distance statistics were calculated for three-date multispectral Landsat 8, three-date Landsat 8 NDVI, and 23-period, 16-day composite Terra MODIS NDVI time series. The results indicate that combining the three datasets maximized the spectral separability of grassland types across all four grassland-type hierarchies. A comparison of the three datasets showed that multispectral Landsat 8 data had the highest JM distance statistics (which indicates the most separability). JM distance statistics calculated by-band and by-period consistently showed that information from spring and fall was more important than summer for separating grassland types. The results showed lower separability for land-use classes within a grassland type versus between grassland types. The spectral separability of pairwise comparisons incorporating land use between grassland types varied, indicating that land use does affect spectral separability in some instances. On the other hand, JM distance statistics did not substantially drop when more refined grassland types were aggregated to coarser grassland type classes (e.g. Level-1: cool- and warm-season), indicating that land use does not negatively affect the spectral separability of functional grassland types. The results indicate low spectral separability between brome and fescue but moderate to high separability between native and CRP, suggesting the use of a Level-1 or Level-2 thematic classification scheme for the study area. Finally, random forest models were constructed and evaluated using 2015 FSA 578 data and four datasets of remotely sensed data in two adjacent Landsat scenes (path/rows). Models were created for each of the four grassland hierarchies. The results showed that out-of-bag (OOB) error increased with grassland hierarchy complexity (the number of thematic classes) and OOB error was lowest for the combined remotely sensed dataset. Mapping CRP as a separate grassland type resulted in low producer’s accuracy levels, with CRP largely mapped as warm-season grasslands, suggesting the Level-1 classification scheme was appropriate for regional mapping of grassland types. Path/rows 27/33 and 28/33 had OOB overall accuracy levels of 87% and 92%, respectively. User’s and producer’s accuracy levels indicate that cool-season grasslands were mapped more accurately in path/row 27/33 where that class is more dominant than in 28/33. Using test data (withheld verification data) unexpectedly increased overall accuracy levels by 4% and 6% over OOB accuracies, which may have resulted from varying data proportions between OOB and test data, suggesting the need for further evaluation.
Carboxylated Organic Matter Influences Magnesium Uptake in Three Low-Temperature Dolomite Models
(University of Kansas, 2018-08-31) Yoerg, Adam; Roberts, Jennifer; Stotler, Randy; Olcott, Alison
Numerous geochemical models explain the formation of dolomite at low temperature, a controversial mineral due to its abundance in geological deposits but paucity in modern environments. Several of these models are based on environments where dolomite either forms in the modern or is hypothesized to have formed in the past– mixing zones, sabkhas, and alkaline lakes. In the last twenty years, results of field and laboratory studies have found that microorganisms can promote the precipitation of dolomite at low temperature, either through active metabolism or by providing a reactive surface for mineral nucleation. The work summarized here utilizes bench-scale laboratory batch experiments to study simplified geochemical environments associated with low temperature dolomite formation both containing and excluding synthetic carboxylated organic matter in the form of functionalized polystyrene microspheres. These environments were characterized by their pH, alkalinity, and salinity to form geochemical end members. In effect, this combines longstanding geochemical models of dolomite formation with a mechanism known to overcome kinetic barriers to dolomite formation at low temperature. Experiments did not demonstrate formation of significant amounts of dolomite, however, data suggest that while bulk precipitation products reflect the specific geochemical environments, the presence of carboxylated organic matter promotes the incorporation of magnesium into the precipitate across geochemical environments. The amount of magnesium in the precipitate on the microsphere surface appears to be a function of the Mg/Ca ratio of the bulk solution. Magnesium is observed both in precipitates forming on the microsphere surface and is more broadly distributed in the bulk precipitate when microspheres are present. These results suggest that carboxylated organic matter can sequester magnesium into precipitates, which could have implications for magnesium availability during diagenesis. Results from experiments studying the impact of carboxylated organic matter on dolomitization of calcium carbonate sediments in mixing, sabkha, and artificial fluids are inconclusive. These negative results potentially arise from short experimental time scales and scaling issues during analysis. Future low temperature dolomitization experiments should include advection in the experimental design to provide the mass transfer presumably necessary for significant dolomitization.
The stratigraphy of the Quaternary alluvium in the Great Bend Prairie, Kansas
(University of Kansas, 1988-05-31) Rosner, Malia LaNita
The Quaternary alluvial aquifer beneath the Great Bend Prairie in south-central Kansas serves as a major source of water for irrigation and domestic use. Low quality saline water, however, intrudes locally from Permian and possibly Cretaceous bedrock and mixes with the less dense freshwater in the aquifer. Grain-size analysis of samples from three wells of a natural recharge study was correlated to the respective gamma logs. The correlation was then applied to the gamma logs from an observation well network, established by the Kansas Geological Survey and Groundwater Management District No. 5, to improve the stratigraphic interpretation. The stratigraphy of the area is defined from the surface down as (1) dune sands, (2) near surface silt-clay, (3) a section of variable lithology, (4) basal sand, and (5) bedrock. The alluvium was mainly deposited by the Arkansas River as it aggraded its channel and moved northward laterally by avulsion to its present position. The gamma logs and grain-size analysis show fining upward sequences in the sediments. The near surface silt-clay and basal sand are the only two lithologies that are continuous and could be mapped across the study area. The near surface silt-clay can influence aquifer recharge. If saline water and then freshwater is allowed to come in contact with the silt-clay, then the permeability of the silt-clay will be significantly reduced. This will decrease recharge to the aquifer. The basal sand tends to be thicker in the paleovalleys and thinner over the paleoridges. This sand serves as an aquifer in the area. The variable lithology section is the result of lateral shifting of the streams in the study area.
Rock Fabric Controls on Pore Evolution and Porosity-Permeability Trends in Oolitic Grainstone Reservoirs and Reservoir Analogs
(University of Kansas, 2018-12-31) Goodner, Hamilton; Rankey, Eugene C.; Watney, Lynn; Zhang, Chi
Although the general influence of rock fabric on porosity and permeability (Φ-k) within carbonates is well documented, if and how pore evolution and Φ-k scatter quantitatively relate to depositional fabric remains poorly constrained. This project empirically explores this uncertainty within oolitic grainstones from a range of geologic ages and diagenetic histories to understand depositional sediment-pore relationships, and how they can evolve with lithification. Integrating data from point counting, digital image analysis, nuclear magnetic resonance and core analysis of Holocene, Pleistocene, Pennsylvanian, and Mississippian oolitic grainstones reveals quantitative relations among rock fabric, pores, and petrophysical parameters. Oolitic grainstones of similar sedimentology taken from distinct diagenetic scenarios display a unique combination of pore size, shape, spatial distribution, and Φ-k character. Within each scenario, grain size, sorting, and type are correlated more closely with pore attributes and k than cementation and compaction. Collectively, these results are interpreted to suggest that diagenesis defines the absolute values of pore attributes and petrophysical parameters, but sedimentology controls the trends or variability within an oolitic succession. The implication of these findings is that petrophysical variability within oolitic reservoirs closely follows sedimentologic trends, which may be predictable within a stratigraphic framework.
Stratal and Petrophysical Complexity Expressed in Seismic Reflection Patterns within Isolated Carbonate Platforms
(University of Kansas, 2018-12-31) Duarte, Adrienne M; Rankey, Eugene C.; Franseen, Evan K.; Tsoflias, George P.
Seismic data are fundamental tools for evaluating and exploiting hydrocarbon resources, yet how the heterogeneous nature of carbonates complicates imaging, interpretation, and predictability of reservoir properties from seismic data is poorly understood. To test the hypothesis that changes in geologic inputs create a statistically distinct impact on seismic character of isolated platforms, this project generated synthetic seismic volumes from geologic models in which geologic heterogeneities (e.g. vertical and lateral trends in facies, porosity, and impedance) were isolated and varied, and their seismic impacts evaluated. Twenty-eight geologic scenarios, each of which addresses a single variable of geologic heterogeneity, form the basis for qualitatively illustrating the influence of stratal and petrophysical complexity on seismic volumes. The geological and petrophysical inputs are derived from modern and ancient analogs that capture a range of depositional and petrophysical variability. Subtle seismic reflection patterns captured by seismic attributes facilitate quantitative insights for understanding the relationship between geology and seismic character. Exploring statistical distinctions among scenarios reveals the capability for attributes to predict rock properties (e.g., average porosity) accurately in certain geological models. Qualitative results illustrate the seismic character of models in which stratigraphic architecture and petrophysical complexity varied reveals marked differences in phase and amplitude leading to both accurate and inaccurate geological interpretations. Quantitative results illustrate that as the type of geological heterogeneity changes, the quality of prediction between attributes and average porosity (expressed on a trace-by-trace, and net pore volume basis) also varies, emphasizing the importance of geology on attributes. These results provide insights into the complex controls on the seismic character of isolated platforms and potential pitfalls in interpretation.
Simulating complex conductivity in carbonate rocks: using digital carbonate rocks and comparison to laboratory measurements
(University of Kansas, 2018-12-18) Colgin, James Edward; Zhang, Chi; Tsoflias, George; Li, Xianglin
Digital rock physics involves the modern microscopic imaging of geomaterials, digitalization of the microstructure, and numerical simulation of physical properties of rocks. This physics-based approach can give important insight into understanding properties of reservoir rocks, and help reveal the link between intrinsic rock properties and macroscopic geophysical responses. Our focus is the simulation of the complex conductivity of carbonate reservoir rocks using reconstructed 3D rock structures from high-resolution X-ray micro computed tomography (micro-CT). Carbonate core samples with varying lithofacies and pore structures from the Cambro-Ordovician Arbuckle Group and the Upper Pennsylvanian Lansing-Kansas City Group in Kansas were used in this study. The wide variations in pore geometry and connectivity of these samples were imaged using micro-CT. A two-phase segmentation method was used to reconstruct a digital rock of solid particles and pores. We then calculated the effective electrical conductivity of the digital rock volume using a pore-scale numerical approach. The complex conductivity of geomaterials is influenced by the electrical properties and geometry of each phase, i.e., the solid and fluid phases. In addition, the electrical double layer that forms between the solid and fluid phases can also affect the effective conductivity of the material. In the numerical modeling, the influence of the electrical double layer is quantified by a complex surface conductance and converted to an apparent volumetric complex conductivity of either solid particles or pore fluid. The effective complex conductivity resulting from numerical simulations were compared to results from laboratory experiments on equivalent rock samples. In general, simulated σ'eff values were below laboratory measurements, while numerical σ''eff values were within reasonable range. The imaging and digital segmentation technique, fundamental rock characteristics, and model assumptions all play an important role in the simulation process.
Interoperability between the StraboSpot graph database and GIS software– A Malpais Mesa Use Case
(University of Kansas, 2018-12-31) Bunse, Emily; Walker, J. Douglas; Stearns, Leigh A.; Taylor, Michael H.
Geographic Information Systems (GIS) have been used by field geoscientists for decades to digitally collect data with several benefits: observations can be made in the field at a map independent scale while using multiple basemaps, the burdensome task of digitizing handwritten field notes and maps back in the office is eliminated, and the use of global positioning systems (GPS) has led to more precisely located observations. Despite the numerous advantages of using GIS in the field geosciences, the lack of agreement upon a standard schema for relational database management systems used in GIS along with new geospatial technologies and the popularization of mobile applications has led to the development of a novel geologic data management system, StraboSpot. StraboSpot consists of a mobile application available for Android and iOS devices for data collection and an online graph database for data storage, management, and sharing. The issue of schema creation has been solved with the development of a lexicon through contributions from the structural geology and tectonics, sedimentology, petrology, and microstructural communities and the utilization of a graph database for storage, which is schema-less by definition. Users of StraboSpot can collect, store, and share their geologic data, making it an all-in-one solution for geoscientists to publish their data using open source techniques. Data is stored in a users’ StraboSpot account which can hold multiple StraboSpot projects consisting of multiple datasets containing Spots. A Spot is a point, line, or polygon containing a set of observations over a user-defined spatial extent. The spatial extent of a Spot can be in real world coordinates (when set using maps or georeferenced aerial imagery), pixel coordinates (when set using a photo) or other systems as needed. Tags, “sticky-note”-like categories, can be used to conceptually group Spots. StraboSpot does not have the cartographic and analysis tools found in a GIS, so it became necessary to establish connections between StraboSpot and commonly-used GIS software, ArcGIS and QGIS. GIS connections – an ArcMap Add-In and QGIS Plug-In – have been designed and programmed which have download and upload capabilities with StraboSpot. Download or upload of a StraboSpot project and dataset occurs through deserialization/serialization and parsing of JSON (Java Script Object Notation) and GeoJSON transferred between the GIS and StraboSpot’s graph database via RESTful communications. I traveled to Malpais Mesa, Inyo County, CA in October 2016, accompanied by two other University of Kansas students working on StraboSpot, to beta test StraboSpot’s mobile app. Malpais Mesa was chosen due to the complexity of the area – it is situated in the Eastern California Shear Zone and the westernmost range of the Basin and Range province – which would adequately test for bugs in the mobile application and create robust StraboSpot data which I then used in the development of the GIS connections. Most importantly, it was an excellent location to compare the geoscientist’s workflow with the capabilities and structure/interface of StraboSpot. The interoperability between StraboSpot and the GIS connections provides users with a user-friendly and seamless method of downloading data collected in the field, performing various analyses such as running topology, and then uploading the “cleaned up” data for further use in StraboSpot. Geoscientists will also be able download all their StraboSpot data and create professional map products using the cartographic layout tools in GIS. The raw data behind those map products will be easily shared through StraboSpot leading to greater transparency, reproducibility, and reuse of geologic data.

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