• 9C-3D seismic interpretation of the Bakken Formation, Banner field, North Dakota

      Davis, Thomas L. (Thomas Leonard), 1947-; Comegys, Lillian R.; Sonnenberg, Stephen A.; Lynn, Walter (Colorado School of Mines. Arthur Lakes Library, 2013)
      The Bakken Petroleum System is a multi-reservoir play with estimated total undiscovered resources of 3.649 BBO oil and 1.85 TCF natural gas in the United States portion of the Williston Basin (Pollastro 2008). The presence of natural fractures in all three members of the Bakken Formation have been linked to high initial production (IP) and cumulative production from the Antelope Field and better reservoir potential in the Elm Coulee Field and Sanish Fields (Sturm and Gomez 2009; Honsberger 2012; Theloy 2011). Therefore, the ability of seismic data to determine the presence, orientation, and density of natural fractures is an important achievement for petroleum exploration and exploitation. The STAMPEDE 9-component seismic survey is located in Mountrail County, North Dakota, in the Banner Field, southeast of the Parshall and Sanish Fields. It is the goal of the Reservoir Characterization Project to analyze the structural influences on reservoir properties in the STAMPEDE survey area using the compressional and pure shear seismic volumes supplemented by the public well information available on the North Dakota Industrial Commission website. Fracturing induced by basement faulting and lithology changes is detectable using multicomponent seismic data in the Stampede seismic survey. Shear wave splitting analysis delineates zones of different fracture orientation and density. These areas correlate to interpreted fault intersections and the predicted area of increased fracture frequency based on facies changes in the Middle Bakken Member and its mechanical stratigraphy. Wrench fault mechanics are at work in the study area, creating isolated convergent and divergent stress regimes in the separate fault blocks. Main fault interpretations are based on shear wave isochron mapping, wireline log mapping, seismic panel observations. Fracture interpretations were made on the analysis of shear time and amplitude anisotropy maps and the correlation of a P-wave Velocity Variation with Azimuth (VVAZ) map. The corroboration of the shear time anisotropy with the VVAZ interpretation strengthens the interpretation of fractures present in the study area. Also, this provided an opportunity to contrast the sensitivity of these two methods to azimuthally anisotropic media. The methodology of this study can be used elsewhere to identify areas of increased fracture intensity and the the orientation of these fractures. This information can then be used to plan drilling locations and guide lateral paths.
    • Advanced ICP-MS methods for examining the stability of silver nanoparticles in natural waters

      Ranville, James F.; Higgins, Christopher P.; Gately, Thomas Joseph; Braley, Jenifer C. (Colorado School of Mines. Arthur Lakes Library, 2013)
      The rapid growth of nanotechnology, specifically the incorporation of engineered nanoparticles (ENP's) into various products, will almost certainly lead to their release into the environment. Silver nanoparticles (nano-Ag) have seen widespread use in consumer products as a result of their antimicrobial properties. Silver ion (Ag+), is known to be toxic to a large variety of organisms, especially aquatic species. The release of Ag+ from nano-Ag under relevant environmental conditions is not currently well understood, as many studies use unrealistically high concentrations. This is in part due to limitations in the techniques used to detect and characterize ENP's. Using Single Particle Inductively Coupled Plasma Mass Spectrometry (SP-ICP-MS), a newly developed method to examine ENPs we are able to detect and quantify both nano-Ag and Ag+ at part per trillion concentrations, considered a realistic environmental level. In a collaborative study with the Trent University, PVP-coated 50 nm nano-Ag particles were introduced into several mesocosms within a lake. Their fate (particle number, dissolution) was monitored by a number of methods including SP-ICP-MS, FFF-ICPMS, and total Ag analysis. Before the experiment could proceed a preservation method was needed to allow sample transport from the Ontario Lake to the lab in Colorado. Flash freezing using liquid nitrogen was found to be an effective method for preserving the particles that there was minimal change to the particle size and number. The samples were stored at -80 degrees C until the time of analysis. 60 nm PVP capped particles were initially found to be 58.3 ± 5.3 nm and the flash frozen particles were found to be 58.4± 5.2 nm. A series of lab experiments were also performed using lake water in which the stability of nano-Ag particles was examined. The particles were found to decrease in diameter from 50 nm to 36 nm over the course of seven days. Particle number also decreased over the course of the experiment illustrating that further work on methodology is required. Typical decreases in particle number were on the order of 60% over the course of a week. The rate of particle loss/transformation was significantly slower when lake waters were filtered suggesting a role for other suspended sediments or biota in the process. Sterilization using autoclaving provided further evidence for the role of biota but results showed complex behavior depending on the methods used (e.g. filtration and autoclaving). This study further demonstrates the utility of SP-ICP-MS to detect, quantify and characterize ENPs, but further work is needed to fully understand the processes controlling nano-Ag stability in aquatic environments.
    • Advanced platform for development and evaluation of grid interconnection systems using hardware-in-the-loop, An

      Sen, Pankaj K.; Lundstrom, Blake R.; Ammerman, Ravel F.; Kroposki, Benjamin David, 1968- (Colorado School of Mines. Arthur Lakes Library, 2013)
      The recently highlighted vulnerabilities, environmental effects, and critically aging status of the North American Electric Power System (EPS) are fueling a shift towards a power system paradigm that more fully leverages Distributed Resources (DRs). In order to support and accelerate DR grid integration, methods to rapidly evaluate DRs against existing grid interconnection standards and assess advanced DRs integrated in complex EPS scenarios are needed. This thesis develops a novel solution for rapid evaluation of DR grid interconnection standard conformance that uses a real-time simulator and a single graphical user interface to automate the time-consuming process required for the many repeated conformance tests of IEEE Std 1547.1. A method for evaluating advanced DR grid integration scenarios using Power Hardware-in-the-Loop (PHIL) is presented. The results from a novel demonstration of a DR grid integration scenario using both PHIL-based and hardware-only approaches are presented, establishing the utility and validity of the PHIL method.
    • Advanced three-dimensional analysis of concrete structures using nonlinear truss models

      Kiousis, Panagiotis Demetrios, 1956-; Ilgadi, Otman B.; Amery, Hussein A., 1958-; Crocker, Joseph P.; Martin, P. A.; Wang, Judith (Colorado School of Mines. Arthur Lakes Library, 2013)
      A three-dimensional truss-based simulation of reinforced concrete is presented in this study. The truss model has been implemented to simulate the response of columns under compression, shallow beams under bending, and deep beams under shear. The concrete truss elements are modeled based on advanced constitutive equations that account for confinement dependent hardening followed by softening. The reinforcing steel is modeled as an elastoplastic material, while the steel-concrete interface is modeled as one of perfect bonding. A computer program with an elaborate graphical interface was developed to implement this model. The program includes a three-dimensional mesh generation, a pre- and post-processing interface, and a computational component that implements a non-linear iterative finite element solution. The computational advantages, as well as the challenges of this approach are discussed. The model has been calibrated based on an extensive set of published experiments, which range in geometry, material parameters, loading, and levels of reinforcement. The validation of the truss model based on multiple experiments is followed by detailed observation on the progressive failure patterns that allow for improved insight of the mechanisms that eventually lead to the failure of columns, shallow beams and deep beams. This analysis verifies some well-established trends of ductility, strength, and failure pattern development. It also sheds new light on the limits of the contributions of transverse reinforcement to the strength and ductility of reinforced concrete elements. In conclusion, the model presented in this study is a useful research and design tool which enables the detailed analysis of reinforced concrete elements, where issues of strength, ductility, and progressive failure patterns can be examined.
    • Aeromagnetic signature of the geology and mineral resources near the Pebble porphyry Cu-Au-Mo deposit, southwest Alaska

      Zhou, Wendy; Anderson, Eric D.; Hitzman, Murray Walter; Monecke, Thomas; Nabighian, Misac N.; Cohen, Ronald R. H. (Colorado School of Mines. Arthur Lakes Library, 2013)
      Aeromagnetic data are used to better understand the geology and mineral resources near the Late Cretaceous Pebble porphyry Cu-Au-Mo deposit in southwestern Alaska. The reduced-to-pole (RTP) transformation of regional-scale aeromagnetic data show that the Pebble deposit is within a cluster of magnetic anomaly highs. Similar to Pebble, the Iliamna, Kijik, and Neacola porphyry copper occurrences are in magnetic highs that trend northeast along the crustal-scale Lake Clark fault. A high-amplitude, short- to moderate-wavelength anomaly is centered over the Kemuk occurrence, an Alaska-type ultramafic complex. Similar anomalies are found west and north of Kemuk. A moderate-amplitude, moderate-wavelength magnetic low surrounded by a moderate-amplitude, short-wavelength magnetic high is associated with the gold-bearing Shotgun intrusive complex. The RTP transformation of the district-scale aeromagnetic data acquired over Pebble permits differentiation of a variety of Jurassic to Tertiary magmatic rock suites. Jura-Cretaceous basalt and gabbro units and Late Cretaceous biotite pyroxenite and granodiorite rocks produce magnetic highs. Tertiary basalt units also produce magnetic highs, but appear to be volumetrically minor. Eocene monzonite units have associated magnetic lows. The RTP data do not suggest a magnetite-rich hydrothermal system at the Pebble deposit. The 10 km upward continuation transformation of the regional-scale data shows a linear northeast trend of magnetic anomaly highs. These anomalies are spatially correlated with Late Cretaceous igneous rocks and in the Pebble district are centered over the granodiorite rocks genetically related to porphyry copper systems. The spacing of these anomalies is similar to patterns shown by the numerous porphyry copper deposits in northern Chile. These anomalies are interpreted to reflect a Late Cretaceous magmatic arc that is favorable for additional discoveries of Late Cretaceous porphyry copper systems in southwestern Alaska. Aeromagnetic data help to understand the three-dimensional distribution of plutonic rocks near the Pebble porphyry copper deposit. Magnetic susceptibility measurements show that rocks in the Pebble district are more magnetic than rocks of comparable compositions in the Pike Creek-Stuyahok Hills volcano-plutonic complex. The reduced-to-pole transformation of the aeromagnetic data demonstrates that the older rocks in the Pebble district produce strong magnetic anomaly highs. The tilt derivative transformation highlights a strong, northeast-trending structural grain attributed to Tertiary volcanic rocks. Multiscale edge detection maps near-surface magnetic sources that are mostly outward dipping and coalesce at depth in the Pebble district. The total horizontal gradient of the 10 km upward continued magnetic data map a circular, deep magnetic contact along which the porphyry deposits occur. Forward and inverse magnetic modeling show that the magnetic rocks in the Pebble district extend to depths greater than 9 km. The magnetic inversion is constrained by a near-surface, three-dimensional geologic model that is attributed with measured magnetic susceptibilities from various rock types in the region. The inversion results indicate that several near-surface magnetic features with moderate susceptibilities converge with depth into magnetic bodies with higher susceptibilities. This deep magnetic source appears to rise towards the surface in several areas. An isosurface value of 0.02 SI is used to depict the magnetic contact between outcropping granodiorite and non-magnetic sedimentary host rocks. The contact is shown to be outward dipping. At depths around 5 km nearly the entire model exceeds the isosurface value indicating the limits of non-magnetic host material. The inversion results show the presence of a relatively deep, northeast trending magnetic low that parallels lineaments mapped by the tilt derivative. This deep low represents a strand of the Lake Clark fault. The geodynamic setting of an accreted island-arc terrane represent a region in which several types of mineral resources may occur. The mineral resources from southwest Alaska are classified into greenstone-hosted, oxidized intrusion-related, reduced intrusion-related, and epithermal. Aeromagnetic data are related to the classified mineral resource and outcropping geology to better understand the distribution of gold-rich mineral resources. Three magnetic domains are defined by the reduced-to-pole, upward continue, and tilt derivative transforms. The greenstone-hosted mineral resources that include VMS are mapped along magnetic lineaments mostly landward of the accreted island-arc. The oxidized intrusion-related mineral resources that include porphyry copper, skarn, and Alaska-type ultramafic-mafic complexes occur along magnetic anomaly highs in the Peninsular and Kahiltna domains. Characteristic short wavelength, high amplitude magnetic anomalies suggest additional Alaska-type ultramafic-mafic complexes and skarn resources in the Kahiltna and Kuskokwim domain. Magnetic depth estimates indicate potential greenstone-hosted and oxidized intrusion-related resources occur beneath 100 m of glacial deposits. Reduced intrusion-related resources are best imaged in the more landward, Kuskokwim magnetic domain. Epithermal resources are not well imaged. The mineral potential map highlights areas most favorable for additional mineral resources.
    • Aging effects on the fatigue performance of deep rolled bar steels

      Matlock, David K.; Barlow, Timothy D.; Findley, Kip Owen; De Moor, Emmanuel (Colorado School of Mines. Arthur Lakes Library, 2013)
      The effects of solute nitrogen on the strain aging response after deep rolling and on the effects of deep rolling at a temperature selected to maximize the difference in the dynamic strain aging response on the fatigue behavior of two medium carbon bar steels was evaluated in reverse bending at room temperature. The nominally 0.38 wt pct carbon hot rolled bar steels included a plain carbon steel alloy specically designed to have an elevated free nitrogen content and a steel alloyed with 0.09 wt pct vanadium, 0.010 wt pct titanium, and 0.020 wt pct aluminum in order to reduce solute nitrogen through precipitation. The static strain aging response of the two alloys was evaluated at room temperature on samples prestrained to 2.5% and aged at temperatures between 100 degrees C and 260 degrees C. The microalloyed steel exhibited a peak strain aging index at 220 degrees C, while the plain carbon steel exhibited a constant strain aging index at all temperatures tested nearly the same as the peak value of the microalloyed steel. Stress reversal tests at temperatures between 100 degrees C and 300 degrees C showed that the microalloyed steel exhibited limited dynamic strain aging (DSA) over the temperature range tested while at 150 degrees C the plain carbon steel exhibited a maximum in DSA. Samples were deep rolled at room temperature and at 150 degrees C, and aged after room temperature deep rolling at 100 degrees C, a temperature selected to maximize the difference in strain aging index between the two alloys. The effect of deep rolling at room temperature, is an increase in the endurance limit of 55% over the as received condition. For the microalloyed steel, the room temperature deep rolled endurance limit was equivalent to the samples aged at 100 degrees C and those rolled at 150 degrees C. In contrast the plain carbon steel with an elevated free nitrogen content exhibited 9.2% increase in endurance limit when aged and an 18.2% increase after deep rolling at 150 degrees C. The enhanced response of the high nitrogen plain carbon steel was attributed to the development of more stable dislocation structures and correspondingly residual stress fields due to the effects of solute pinning on dislocations.
    • Algorithms and analysis for simulation of deterministic and stochastic Ginzburg-Landau models

      Ganesh, Mahadevan; Thompson, Ty; Vincent, Tyrone; Bialecki, Bernard; Tenorio, Luis; Wu, David T. (Colorado School of Mines. Arthur Lakes Library, 2013)
      We focus on the efficient simulation of nondeterministic critical phenomena in the Ginzburg-Landau (GL) model for superconductivity. Deterministic GL is widely used to study the formation of vortex configurations in thin superconductors. When such phenomena are essentially nondeterministic, the Langevin version of the time dependent GL problem applies, and simulation presents a significant computational challenge. To investigate nondeterministic dynamics, we work on 2-manifolds having rotational symmetry about the axis of a constant magnetic field, and consider an ideal (superconductor or normal) initial state. Using highly efficient deterministic schemes, we first motivate the stochastic extension, and demonstrate an ad hoc approach for simulating the evolution of dense, locally stable vortex configurations. For stochastic simulations, we identify the opportunity to use a spectral Galerkin approach. Building upon a linearized Crank-Nicolson scheme, we use generalized spectral decompositions to reliably achieve a reduction in dimensionality. The efficiency of the method is examined through comparisons with Monte Carlo estimators, and our efforts at qualifying the perturbation approach are discussed.
    • Aluminium nitride piezoelectric thin films reactively deposited in closed field unbalanced magnetron sputtering for elevated temperature 'smart' tribological applications

      Lin, Jianliang; Moore, J. J. (John Jeremy), 1944-; Hasheminiasari, Masood; Scales, John Alan; Olson, D. L. (David LeRoy); Ahrenkiel, Richard K.; Sproul, William (Colorado School of Mines. Arthur Lakes Library, 2013)
      Smart high temperature piezoelectric aluminum nitride (AlN) thin films were synthesized by reactive magnetron sputtering using DC; pulsed-DC, and deep oscillation modulated pulsed power (DOMPP) systems on variety of substrate materials. Process optimization was performed to obtain highly c-axis texture films with improved piezoelectric response via studying the interplay between process parameters, microstructure and properties. AlN thin films were sputtered with DC and pulsed-DC systems to investigate the effect of various deposition parameters such as reactive gas ratio, working pressure, target power, pulsing frequency, substrate bias, substrate heating and seed layers on the properties and performance of the film device. The c-axis texture, orientation, microstructure, and chemical composition of AlN films were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). A Michelson laser interferometer was designed and built to obtain the converse piezoelectric response of the deposited AlN thin films. Thin films with narrow AlN-(002) rocking curve of 2.5 degrees were obtained with preliminary studies of DOMPP reactive sputtering. In-situ high temperature XRD showed excellent thermal stability and oxidation resistance of AlN films up to 1000 degrees C. AlN films with optimized processing parameters yielded an inverse piezoelectric coefficient, d33 of 4.9 pm/V close to 90 percent of its theoretical value.
    • Analysis and correlation of growth strata of the Cretaceous to Paleocene Lower Dawson Formation: insight into the tectono-stratigraphic evolution of the Colorado Front Range

      Aschoff, Jennifer L.; Harvey, Korey Tae; Trudgill, Bruce, 1964-; Kluth, Chuck (Colorado School of Mines. Arthur Lakes Library, 2013)
      Despite numerous studies of Laramide-style (i.e., basement-cored) structures, their 4-dimensional structural evolution and relationship to adjacent sedimentary basins are not well understood. Analysis and correlation of growth strata along the eastern Colorado Front Range (CFR) help decipher the along-strike linkage of thrust structures and their affect on sediment dispersal. Growth strata, and the syntectonic unconformities within them, record the relative roles of uplift and deposition through time; when mapped along-strike, they provide insight into the location and geometry of structures through time. This paper presents an integrated structural- stratigraphic analysis and correlation of three growth-strata assemblages within the fluvial and fluvial megafan deposits of the lowermost Cretaceous to Paleocene Dawson Formation on the eastern CFR between Colorado Springs, CO and Sedalia, CO. Structural attitudes from 12 stratigraphic profiles at the three locales record dip discordances that highlight syntectonic unconformities within the growth strata packages. Eight traditional-type syntectonic unconformities were correlated along-strike of the eastern CFR distinguish six phases of uplift in the central portion of the CFR.is area. The correlation of the syntectonic unconformities shows diachronous development of emerging structures that formed the CFR. The structures first developed in the South, then propagated in a northward direction along the eastern side of the CFR. Lithofacies and paleocurrent analysis within the growth strata record the transition from fluvial (confined) deposition to unconfined fluvial/megafan deposition. Sediment entry points for the fluvial (confined) and unconfined fluvial/megafan depositional systems were controlled by the lateral linking of along strike thrust faults (i.e., transverse or transfer zones) that bound the CFR. Provenance analysis supports the linkage of thrust structures controlling the provenance and sediment entry points to the Denver Basin. Petrographic analysis of twelve thin sections within the lower Dawson Formation shows two distinct petrofacies indicative of two fluvial megafan systems when considered with lithofacies and paleocurrent analysis. An unroofing signal was also identified that developed in response to the removal of Phanerozoic cover and Precambrian basement that covered the CFR due to emerging Laramide structures. The study has implication for predicting clastic sediment distribution in punctuated foreland basins, which ultimately controls reservoir presence for conventional plays and clay content for unconventional shale plays.
    • Analysis and design of a smart-inverter for renewable energy interconnection to the grid

      Simões, M. Godoy; Al-Durra, Ahmed; Reznik, Aleksandr; Ammerman, Ravel F.; Vincent, Tyrone (Colorado School of Mines. Arthur Lakes Library, 2013)
      This Master thesis presents a three phase grid connected DC/AC inverter with active and reactive power (VAR) control for medium size renewable and distributed DC energy sources. The inverter, based on a voltage sourced inverter (VSI) configuration, allows the local residential energy generation to actively supply reactive power to the utility grid, at the same time, this topology allows to work this installation in stand alone (grid disconnected) mode maintaining nominal and clean voltage at nominal power. A low complexity grid synchronization method was introduced to generate direct and quadrature components of the grid voltage in a simple and computationally efficient manner in order to generate a synchronized current reference for the current loop control. The main goal of this project is to study and to implement the control system of a grid-tied with LCL filter. The objectives of the project are divided in two parts: theoretical and experimental work. In the theoretical part, harmonics, inverter topologies, filter topologies, the design and the performance of the system will be discussed. Simulations were performed on Matlab/Simulink platform and a prototype was also developed in the lab to prove the effectiveness of the designed filter, controllers and grid synchronization method. The dSPACE hardware in the loop (HIL) was used, providing a good solution for laboratory implementation.
    • Analysis and suppression of passive noise in surface microseismic data

      Batzle, Michael L.; Snieder, Roel, 1958-; Forghani-Arani, Farnoush; Willis, Mark; Haines, Seth; Martin, P. A.; Tutuncu, Azra; Krahenbuhl, Richard A. (Colorado School of Mines. Arthur Lakes Library, 2013)
      Surface microseismic surveys are gaining popularity in monitoring the hydraulic fracturing process. The effectiveness of these surveys, however, is strongly dependent on the signal-to-noise ratio of the acquired data. Cultural and industrial noise generated during hydraulic fracturing operations usually dominate the data, thereby decreasing the effectiveness of using these data in identifying and locating microseismic events. Hence, noise suppression is a critical step in surface microseismic monitoring. In this thesis, I focus on two important aspects in using surface-recorded microseismic seismic data: first, I take advantage of the unwanted surface noise to understand the characteristics of these noise and extract information about the propagation medium from the noise; second, I propose effective techniques to suppress the surface noise while preserving the waveforms that contain information about the source of microseisms. Automated event identification on passive seismic data using only a few receivers is challenging especially when the record lengths span over long durations of time. I introduce an automatic event identification algorithm that is designed specifically for detecting events in passive data acquired with a small number of receivers. I demonstrate that the conventional ST A/LT A (Short-term Average/Long-term Average) algorithm is not sufficiently effective in event detection in the common case of low signal-to-noise ratio. With a cross-correlation based method as an extension of the ST A/LT A algorithm, even low signal-to-noise events (that were not detectable with conventional ST A/LT A) were revealed. Surface microseismic data contains surface-waves (generated primarily from hydraulic fracturing activities) and body-waves in the form of microseismic events. It is challenging to analyze the surface-waves on the recorded data directly because of the randomness of their source and their unknown source signatures. I use seismic interferometry to extract the surface-wave arrivals. Interferometry is a powerful tool to extract waves (including body-wave and surface-waves) that propagate from any receiver in the array (called a pseudo source) to the other receivers across the array. Since most of the noise sources in surface microseismic data lie on the surface, seismic interferometry yields pseudo source gathers dominated by surface-wave energy. The dispersive characteristics of these surface-waves are important properties that can be used to extract information necessary for suppressing these waves. I demonstrate the application of interferometry to surface passive data recorded during the hydraulic fracturing operation of a tight gas reservoir and extract the dispersion properties of surface-waves corresponding to a pseudo-shot gather. Comparison of the dispersion characteristics of the surface waves from the pseudo-shot gather with that of an active shot-gather shows interesting similarities and differences. The dispersion character (e.g. velocity change with frequency) of the fundamental mode was observed to have the same behavior for both the active and passive data. However, for the higher mode surface-waves, the dispersion properties are extracted at different frequency ranges. Conventional noise suppression techniques in passive data are mostly stacking-based that rely on enforcing the amplitude of the signal by stacking the waveforms at the receivers and are unable to preserve the waveforms at the individual receivers necessary for estimating the microseismic source location and source mechanism. Here, I introduce a technique based on the t - p transform, that effectively identifies and separates microseismic events from surface-wave noise in the t - p domain. This technique is superior to conventional stacking-based noise suppression techniques, because it preserves the waveforms at individual receivers. Application of this methodology to microseismic events with isotropic and double-couple source mechanism, show substantial improvement in the signal-to-noise ratio. Imaging of the processed field data also show improved imaging of the hypocenter location of the microseismic source. In the case of double-couple source mechanism, I suggest two approaches for unifying the polarities at the receivers, a cross-correlation approach and a semblance-based prediction approach. The semblance-based approach is more effective at unifying the polarities, especially for low signal-to-noise ratio data.
    • Analysis of engineered nanomaterials in the environment

      Ranville, James F.; Reed, Robert Bruce; Higgins, Christopher P.; Voelker, Bettina M.; Richards, Ryan; Williams, S. Kim R. (Colorado School of Mines. Arthur Lakes Library, 2013)
      With increasing incorporation of engineered nanoparticles (NPs) into consumer products, there is concern that these materials will be released to the environment with unknown ecological effects. Methods for detection and characterization of these materials at environmentally relevant concentrations are crucial to understanding this potential risk. A relatively new method, single particle inductively coupled plasma mass spectrometry (spICPMS), was applied to analysis of metal oxide NPs such as ZnO, CeO2, and TiO2, as well as silver nanowires and carbon nanotubes. A lack of nanoparticulate "pulses" in spICPMS analysis of nano-ZnO led to a study on ZnO NP solubility in a variety of matrices. Dissolution of nano-ZnO was observed in nanopure water (7.18 - 7.40 mg/L dissolved Zn, as measured by filtration) and Roswell Park Memorial Institute medium (RPMI-1640) (~5 mg/L), but much more dissolution was observed in Dulbecco's Modified Eagle's Medium (DMEM), where the dissolved Zn concentration exceeded 34 mg/L. These results suggest that solution chemistry exerts a strong influence on ZnO NP dissolution and can result in limits on zinc solubility due to precipitation of less soluble solid phases. Detection and sizing of metal-containing NPs was achieved at concentrations predicted for environmental samples (part-per trillion levels) using spICPMS. Sizing of silver nanowires, titanium dioxide and cerium oxide NPs was done by correlating ICP-MS response (pulses) from NPs entering the plasma to mass of metal in dissolved standards. The ratio of NP pulse detections to the total number of readings during analysis was optimized at 2.5% or less to minimize coincident pulses while still allowing definition of a size distribution. Detection of single walled carbon nanotubes (CNTs) was performed using spICPMS. This study focuses on using trace catalytic metal nanoparticles intercalated in the CNT structure as proxies for the nanotubes. The small, variable, amount of trace metal in each CNT makes separation from instrumental background challenging, and multiple approaches to this problem were attempted. To highlight the potential of spICPMS in environmental studies the release of CNTs from polymer nanocomposites into solution was monitored, showcasing the technique's ability to detect changes in released CNT concentrations as a function of CNT loading.
    • Analysis of global debris-flow fatalities and related socioeconomic factors from 1950 to 2011, An

      Santi, Paul M. (Paul Michael), 1964-; Dowling, Casey Alexander; Higgins, Jerry D.; Zhou, Wendy (Colorado School of Mines. Arthur Lakes Library, 2013)
      Debris flows cause significant damage and fatalities throughout the world. However, some debris flows only take a few victims, while others kill hundreds, and the differences between these events is not well understood. This study addresses the overall impacts of debris flows on a global scale from 1950 to 2011. Two hundred fourteen events with 77,788 fatalities were recorded from academic publications, newspapers, and personal correspondence. Spatial, temporal, and physical characteristics were documented and evaluated. In addition, multiple socioeconomic indicators were reviewed and statistically analyzed to evaluate if vulnerable populations are disproportionately affected by debris flows. This research provides evidence that populations with lower social, political, or economical standing are more at risk for debris-flow related fatality. Specifically, higher levels of fatalities tend to occur in developing countries, characterized by less wealth, more corrupt governments, and weaker healthcare systems. The median number of deaths per flow in developing countries is 23, but only 6 in advanced countries. The analysis also indicates that debris flow occurrence and deadliness is affected by seasonal precipitation patterns, as the most common trigger for fatal events has been found to be extreme precipitation, particularly in the form of large seasonal events like cyclones and monsoon storms. Rainfall caused or triggered 144 of the 214 fatal debris flows within the database. However, it is the more uncommon and catastrophic triggers, such as earthquakes, and landslide dam bursts that tend to create more deadly debris flows, with a median fatality count greater than 500 while rainfall induced debris flows have a median fatality rate of only 9 per event.
    • Analysis of intelligent compaction field data on layered soil

      Wang, Judith; Mooney, Michael A.; Neff, Aaron M.; Crocker, Joseph P.; Griffiths, D. V. (Colorado School of Mines. Arthur Lakes Library, 2013)
      Intelligent compaction (IC) procedures have been gaining popularity as a way to measure mechanistic soil material properties (e.g. stiffness) during the compaction process for earthwork projects. IC procedures involve the interpretation of roller measured soil stiffness from vibratory roller drum accelerations and offer an advantage over current spot testing methods, as IC provides real-time continuous feedback during the compaction process and 100% test coverage of the earthwork site. The objective of this study is to provide the first detailed analysis of IC field data from vibratory roller compaction of layered soil systems. The interpretation of roller measured soil stiffness is currently ambiguous for two main reasons: (1) IC vibratory rollers provide a composite measure of soil stiffness in layered earthwork situations and (2) roller measured soil stiffness from edge mounted (EM) accelerometers can vary significantly due to rocking motion of the drum. To investigate these issues, left and right EM acceleration data from a vibratory roller are used to compute a composite roller measured soil stiffness at the center of gravity (CG) of the drum. CG soil stiffness, which is not subject to the variations associated with drum rocking, are used to evaluate data from two field sites with multiple 15 - 30 cm thick base/subbase/subgrade lifts to investigate their sensitivities to variable lift materials and thicknesses. CG soil stiffness increases with the addition of subbase and base lifts, showing sensitivity to changes in soil materials. CG soil stiffness also increases with the addition of multiple base lifts, showing sensitivity to an increase in the overall thickness of the base material. CG soil stiffness is not sensitive to small variations in the subbase and base lift thicknesses, showing CG soil stiffness is sensitive to the addition of 15 - 30 cm thick subbase and base lifts but not the small variations in lift thickness associated with each of these lifts.
    • Analysis of low transformation temperature welding (LTTW) consumables: distortion control and evolution of residual stresses

      Liu, Stephen; Thomas, Sindhu; Olson, D. L. (David LeRoy); Mishra, Brajendra; David, S. A. (Stan A.); Feng, Zhili (Colorado School of Mines. Arthur Lakes Library, 2013)
      Distortion and tensile residual stresses have become a major concern in the structural integrity of a welded structure. The tensile residual stress which is undesirable is observed in steel welds after completion of solidification and after the weld is cooled to room temperature. They result due to thermal contraction that occurs during cooling. These tensile residual stresses also give rise to distortion. The deleterious tensile residual stresses in the weld toe region reduce the fatigue life of weld components. Methods like flame straightening, post weld heat treatment and shot peening are used to reduce tensile residual stresses. However, these processes are expensive and time consuming. Finally, a decade ago a solution was targeted to this problem. Inducing compressive residual stresses from martensite transformation surfaced as a solution in order to reduce tensile residual stresses to improve fatigue life of the welded component. Efforts were made to design consumables that can induce compressive residual stresses near the weld toe region via phase transformations. The Martensite start (Ms) and finish (Mf) temperatures are essential parameters in inducing compressive residual stresses. It is important that the martensite transformation begins at lower temperature and finishes at a temperature just above the final temperature to which the final weld is expected to cool. Consumables with lower Ms temperature, 100 degrees C, 150 degrees C, 200 degrees C and 350 degrees C, were designed. Alloy compositions in the consumables play a significant role in affecting the temperatures of phase transformations. This research work presents the comparisons of the experimentally and Sysweld calculated measurements for distortions and residual stresses for different plate thicknesses and also investigates the susceptibility of the low transformation temperature welding steels to intergranular corrosion. It showed that when two sets of welding wires with similar transformation temperatures with different compositions were tested on different plate thicknesses with same heat input both by experiment and simulation, different out-of-plane distortion resulted. Also, alloys with higher chromium equivalent promoted greater compressive residual stresses in the weld toe region which reduced distortion when compared to the ones with higher nickel content. Also residual stress evolution with time graphs were plotted to determine the amount of martensite required to promote compressive residual stresses and to calculate the time required to induce compressive residual stresses. The main aspect of this research is to analyze the behavior of Low Transformation Temperature Welding consumables in terms of distortion and residual stresses on various plate thicknesses.
    • Analysis of salt-sediment interaction associated with steep diapirs and allochthonous salt: Flinders and Willouran ranges, South Australia, and the deepwater northern Gulf of Mexico

      Trudgill, Bruce, 1964-; Hearon, Thomas E.; Rowan, Mark G.; Aschoff, Jennifer L.; Humphrey, John D.; Nummedal, Dag (Colorado School of Mines. Arthur Lakes Library, 2013)
      The eastern Willouran Ranges and northern Flinders Ranges, South Australia contain Neoproterozoic and Cambrian outcrop exposures of diapiric breccia contained in salt diapirs, salt sheets and associated growth strata that provide a natural laboratory for testing and refining models of salt-sediment interaction, specifically allochthonous salt initiation and emplacement and halokinetic deformation. Allochthonous salt, which is defined as a sheet-like diapir of mobile evaporite emplaced at younger stratigraphic levels above the autochthonous source, is emplaced due to the interplay between the rate of salt supply to the front of the sheet and the sediment-accumulation rate, and may be flanked by low- to high-angle stratal truncations to halokinetic folds. Halokinetic sequences (HS) are localized (<1000 m) unconformity-bound successions of growth strata adjacent to salt diapirs that form as drape folds due to the interplay between salt rise rate (R) and sediment accumulation rate (A). HS stack to form tabular and tapered composite halokinetic sequences (CHS), which have narrow and broad zones of thinning, respectively. The concepts of CHS formation are derived from outcrops in shallow water to subaerial depositional environments in La Popa Basin, Mexico and the Flinders Ranges, South Australia. Current models for allochthonous salt emplacement, including surficial glacial flow, advance above subsalt shear zones and emplacement along tip thrusts, do not address how salt transitions from steep feeders to low-angle sheets and the model for the formation of halokinetic sequences has yet to be fully applied or tested in a deepwater setting. Thus, this study integrates field data from South Australia with subsurface data from the northern Gulf of Mexico to test the following: (1) current models of allochthonous salt advance and subsalt deformation using structural analysis of stratal truncations adjacent to outcropping salt bodies, with a focus on the transition from steep diapirs to shallow salt sheets in South Australia; and (2) the outcrop-based halokinetic sequence model using seismic and well data from the Auger diapir, located in the deepwater northern Gulf of Mexico. Structural analysis of strata flanking steep diapirs and allochthonous salt in South Australia reveals the transition from steep diapirs to shallowly-dipping salt sheets to be abrupt and involves piston-like breakthrough of roof strata, freeing up salt to flow laterally. Two models explain this transition: 1) salt-top breakout, where salt rise occurs inboard of the salt flank, thereby preserving part of the roof beneath the sheet; and 2) salt-edge breakout, where rise occurs at the edge of the diapir with no roof preservation. Shear zones, fractured or mixed 'rubble zones' and thrust imbricates are absent in strata beneath allochthonous salt and adjacent to steep diapirs. Rather, halokinetic drape folds, truncated roof strata and low- and high-angle bedding intersections are among the variety of stratal truncations adjacent to salt bodies in South Australia. Interpretation and analysis of subsurface data around the Auger diapir reveals similar CHS geometries, stacking patterns and ratios of salt rise and sediment accumulation rates, all of which generally corroborate the halokinetic sequence model. The results of this study have important implications for salt-sediment interaction, but are also critical to understanding and predicting combined structural-stratigraphic trap geometry, reservoir prediction and hydrocarbon containment in diapir-flank settings.
    • Analysis of the repeatability of time-lapse 3D VSP multicomponent surveys, Delhi field

      Davis, Thomas L. (Thomas Leonard), 1947-; Carvalho, Mariana Fernandes de; Young, Terence K.; Batzle, Michael L. (Colorado School of Mines. Arthur Lakes Library, 2013)
      Delhi Field is a producing oil field located in northeastern Louisiana. In order to monitor the CO2 sweep efficiency, time-lapse 3D seismic data have been acquired in this area. Time-lapse studies are increasingly used to evaluate changes in the seismic response induced by the production of hydrocarbons or the injection of water, CO2 or steam into a reservoir. A 4D seismic signal is generated by a combination of production and injection effects within the reservoir as well as non-repeatability effects. In order to get reliable results from time-lapse seismic methods, it is important to distinguish the production and injection effects from the non-repeatability effects in the 4D seismic signal. Repeatability of 4D land seismic data is affected by several factors. The most significant of them are: source and receiver geometry inaccuracies, differences in seismic sources signatures, variations in the immediate near surface and ambient non-repeatable noise. In this project, two 3D multicomponent VSP surveys acquired in Delhi Field were used to quantify the relative contribution of each factor that can affect the repeatability in land seismic data. The factors analyzed in this study were: source and receiver geometry inaccuracies, variations in the immediate near surface and ambient non-repeatable noise. This study showed that all these factors had a significant impact on the repeatability of the successive multicomponent VSP surveys in Delhi Field. This project also shows the advantages and disadvantages in the use of different repeatability metrics, normalized-root-mean-square (NRMS) difference and signal-to-distortion ratio (SDR) attribute, to evaluate the level of seismic repeatability between successive time-lapse seismic surveys. It is observed that NRMS difference is greatly influenced by time-shifts and that SDR attribute combined with the time-shift may give more distinct and representative repeatability information than the NRMS difference.
    • Analytical solutions for multiple-matrix in fractured reservoirs: application to conventional and unconventional reservoirs

      Kazemi, Hossein; Torcuk, Mehmet Ali; Wu, Yu-Shu; Tutuncu, Azra; Hoffman, B. Todd (Colorado School of Mines. Arthur Lakes Library, 2013)
      In this thesis, I present a new method to model heterogeneity and flow channeling in petroleum reservoirs--specially reservoirs containing interconnected microfractures. The method is applicable both to conventional and unconventional reservoirs where the interconnected microfractures form the major flow path. The flow equations, which could include flow contributions from matrix blocks of various size, permeability and porosities, are solved by the Laplace transform analytical solutions and finite-difference numerical solutions. The accuracy of flow from and into nano-Darcy matrix blocks is of great interest to those dealing with unconventional reservoirs. Thus, matrix flow equations are solved using both pseudo-steady-state (PSS) and unsteady-state (USS) formulations. The matrix blocks can be of different size and properties within the representative elementary volume (REV) in the analytical solutions and within each control volume (CV) in the numerical solutions. While the analytical solutions were developed for slightly compressible linear systems, the numerical solutions are general and can be used for non-linear multi-phase, multi-component flow problems. The mathematical solutions were used to analyze the long-term performance of a gas well and two oil wells in two separate unconventional reservoirs. Finally, the formulations were used to assess enhanced oil recovery potential from a typical nano-Darcy matrix block. It is concluded that matrix contribution to flow is very slow in a typical low-permeability unconventional reservoir and much of the enhanced production is from the fluids contained in the microfractures than in the matrix. In addition to field applications, the mathematical formulations and solution methods are presented in a transparent fashion to allow easy utilization of the techniques for reservoir and engineering applications.
    • Anthropomorphic adaptation of a mechanically-variable, near-infinite range-of-stiffness mechanism

      Petrella, Anthony J.; Silverman, Anne K.; Cano, Daniel S.; Weir, Richard F.; Steele, John P. H. (Colorado School of Mines. Arthur Lakes Library, 2013)
      Traditional mechatronic systems utilize stiff actuators, but applications such as prostheses, rehabilitation exoskeletons, legged robots, and industrial robotics have begun to integrate variable-compliance mechanisms into their systems. Several variable-compliance mechanisms have been designed and tested, but they tend to have low ranges of stiffness and complex designs. A variable-compliance system known as the Adjustable Mechanism with a Nominally Infinite Range of Stiffness (AMNIRS) has been previously designed and tested. The AMNIRS device can theoretically achieve stiffnesses from zero to rigid. Through this work, a continuation of the AMNIRS device, AMNIRS-II, has been developed and tested. AMNIRS-II is an improved design that addresses several design limitations in the original AMNIRS device. In addition, AMNIRS-II is smaller than the original AMNIRS, and therefore provides an anthropomorphic configuration. AMNIRS-II was developed in two stages: miniaturization and characterization. The miniaturization phase of the project adapted the original AMNIRS design into a compact device that emulated the physical characteristics of a human elbow. A prototype for the AMNIRS-II was built and characterized. The characterization phase quantified key attributes of the AMNIRS-II system. The AMNIRS-II device included an integrated stiffness setting motor. The parameters that were characterized included the rotational stiffness, elastic energy storage, and stiffness-varying capabilities. The results of the characterization verified the desired characteristics of AMNIRS-II. AMNIRS-II is a compact device that may be integrated into a prosthetic forearm in future work.
    • Arsenic removal from enargite with sodium carbonate using complete and partial oxidized roasting

      Taylor, Patrick R.; Dagdelen, Kadri; Putra, Teuku Andika Rama; Anderson, Corby G.; Miller, Hugh B.; Spiller, D. Erik; Hart, William Mark (Colorado School of Mines. Arthur Lakes Library, 2013)
      Over the past few decades, arsenic-bearing enargite concentrate have become more prevalent in the mining industry. The high arsenic content in enargite presents a problem to copper smelters, as the ability to meet stricter environmental standards and the ability to market arsenic by-products have hampered profitability. Recently, most smelters will not take a copper concentrate that contains more than 0.5% arsenic. This study investigated a new method of removing arsenic from enargite containing copper concentrates through a pyrometallurgical method. The proposed method was roasting a mixture of sodium carbonate (Na2CO3) and enargite containing copper concentrates to convert the arsenic to a water soluble sodium arsenate while either completely oxidizing the sulfide minerals present or by only partially oxidizing the sulfur minerals. The roast calcine was then water leached to remove the soluble sodium arsenate (Na3AsO4) and the water leached arsenic was precipitated using ferric sulfate (Fe2(SO4)3). The results showed successful arsenic removal with the percentage of arsenic removed and retained in the solution using complete oxidation roasting was about 70% while using partial oxidation the percentage increase to 88%. The copper and iron stayed at the same amount in both methods after the process; while more than 50% sulfur maintained during the partial oxidation roasting. The precipitation resulted as a stable solid ferric arsenate (FeAsO4) either scorodite or arsenic-bearing ferrihydrite compound. Methods to regenerate the sodium carbonate from the precipitation process solutions are proposed along with methods to regenerate ferric sulfate. This study also developed a preliminary process flow sheet and preliminary economic analysis for capital, operating costs and revenue.