• 3-D seismic characterization of the Niobrara Formation, Silo field, Laramie County, Wyoming

      Sonnenberg, Stephen A.; Finley, Elena; Davis, Thomas L. (Thomas Leonard), 1947-; Humphrey, John D. (Colorado School of Mines. Arthur Lakes Library, 2014)
      Silo Field, located approximately 17 miles northeast of Cheyenne, Wyoming, is an important Niobrara oil field. The field produces from open, vertical, natural fractures that trend northwest-southeast across the field. Several proposed ideas for fracture genesis include: differential compaction or folding over basement highs, proximity to regional fault and fracture systems, pore fluid pressure increases due to hydrocarbon generation, and reactivation of pre-existing faults. This study integrated previous work, 3-D seismic, and FMI log analysis in order to determine the nature of faulting and fracturing in Silo Field, the nature of the Permian salt edge, and how basement structure tied in with the observed features. The main features observed in the seismic data were: a fault-bound syncline (possible wrench faults penetrating from the basement through the Niobrara) in the northwestern corner, a possible listric detached fault system in the Niobrara which may be a polygonal fault system in the south-central area, and a northwest-southeast trending Permian salt edge. The overall structure of Silo Field is a structural monocline. The fault-bound syncline feature is present at all of the mapped horizons (basement, Wolfcamp, Permian salt, Sundance, Dakota, Niobrara, Pierre event, and the shallow horizon). In this study, the basement structure appeared to have some control on all of the main features. The open fracture directions within the main field area were oriented parallel to the syncline faults. A lineament analysis showed that some of the listric faults corresponded to surface lineaments, indicating that the fault orientations might be influenced by basement faults. The location of the Permian salt edge appears to follow the syncline faults relatively closely, meaning that basement structure might be controlling the salt edge in Silo Field. Finally, the structural monocline present in the field is partially controlled by differential compaction over the salt edge. However, based on the interpretations of possible basement faults that follow surface lineaments, the structural monocline could also have a component of basement control. All of this information demonstrates that Silo Field is a field heavily controlled by the nature of the basement. By understanding the basement structure of the entire field, it is possible to determine the best way to develop the field in the future.
    • 3D radio reflection imaging of asteroid interiors

      Sava, Paul C.; Ittharat, Detchai; Andrews-Hanna, Jeffrey C.; Snieder, Roel, 1958-; Grimm, Robert E. (Colorado School of Mines. Arthur Lakes Library, 2014)
      Imaging the interior structure of comets and asteroids in 3D holds the key for understanding early Solar System and planetary processes, aids mitigation of collisional hazards, and enables future space investigation. 3D wavefield extrapolation of time-domain finite differences, which is referred to as reverse-time migration (RTM), is a tool to provide high-quality images of the complex 3D-internal structure of the target. Instead of a type of acquisition that separately deploys one orbiting and one landing satellite, I discuss dual orbiter systems, where transmitter and receiver satellites orbit around the asteroid target at different speeds. The dual orbiter acquisition can provide multi-offset data that improve the image quality by illuminating the target from different directions and by attenuating coherent noise caused by wavefield multi-pathing. Shot-record imaging requires dense and evenly distributed receiver coordinates to fully image the interior structure at every source-location. I illustrate a 3D imaging method on a complex asteroid model based on the asteroid 433 Eros using realistic data generated from different acquisition designs for the dual orbiter system. In realistic 3D acquisition, the distribution and number of receivers are limited by the acquisition time, revolving speed and direction of both the transmitter and receiver satellites, and the rotation of the asteroid. The migrated image quality depends on different acquisition parameters (i.e., source frequency bandwidth, acquisition time, the spinning rate of the asteroid) and the intrinsic asteroid medium parameters (i.e., the asteroid attenuation factor and an accurate velocity model). A critical element in reconstructing the interior of an asteroid is to have different acquisition designs, where the transmitter and receivers revolve quasi-continuously in different inclinational and latitudinal directions and offer evenly distributed receiver coordinates in the shot-record domain. Among different acquisition designs, the simplest orbit (where the transmitter satellite is fixed in the longitudinal plane and the receiver plane gradually shifts in the latitudinal direction around the asteroid target) offers the best data coverage and requires the least energy to shift the satellite. To obtain reasonable coverage for successfully imaging the asteroid interior, the selected acquisition takes up to eight months. However, this mission is attainable because the propulsion requirements are small due to the slow (< 10 cm/s) orbital velocities around a kilometer-sized asteroid.
    • Acoustic monitoring of hydraulic stimulation in granites

      Gutierrez, Marte S.; Hood, John Calvin; Mooney, Michael A.; Revil, André, 1970- (Colorado School of Mines. Arthur Lakes Library, 2014)
      Enhanced Geothermal Systems (EGS) have substantial potential as a domestic energy source and is well suited as an alternative to diversify the national energy portfolio due to its high levels of heat and recoverable energy. Hydraulic fracture stimulation of low permeability EGS reservoir rock is widely employed to develop this resource and is generally required to make unconventional resources an economically viable resource. Significant challenges for EGS technology include poor connectivity between injection and production wells during stimulation and difficulty predicting fracture growth (Tester, et al. 2006). This, coupled with notable advances in oil and gas recovery, has made hydraulic fracture mechanics the subject of considerable study. Acoustic emissions, or microseisms, contribute greatly to these studies and have been employed on a wide range of topics in rock mechanic studies. At Colorado School of Mines, acoustic emission technology has been employed to monitor stimulation of cubic granite samples under heated and true triaxial stress environments to simulate deep reservoir conditions. Recorded AE activity was used to determine proper location of production well placement while additional analysis on the fracture process using characteristics such as wave amplitude and hit rates were used to identify stages of activity during fracture propagation. Study of the spatial and time dependence of the initiation and growth of rock fractures is critical to understanding the processes that govern fracture behavior and require details that are not accessible to alternative methods of analysis. Acoustic emissions can provide crucial information and represent an important part of rock mechanics studies.
    • Active robust control of wind turbines

      Mohagheghi, Salman; Rezaei, Vahid; Vincent, Tyrone; Moore, Kevin L., 1960- (Colorado School of Mines. Arthur Lakes Library, 2014)
      The research work conducted in this thesis focuses on robustness of wind energy conversion system with respect to faults in pitch actuator in order to prevent unnecessary emergency shutdown, and keep the turbine operational without significant inefficiency in its overall performance. The objective is to investigate the feasibility of using a fault estimator and a light detection and ranging (LIDAR) system as additional sensors to design a suitable control system for wind turbines. Robust control technique is used to address these issues. Three controllers are proposed in this work that try to address sources of inaccuracy in wind turbine operation: An active fault tolerant controller is first designed using a fault estimator. It is shown that a set of locally robust controllers with respect to the fault, together with a suitable smooth mixing approach, manages to overcome the problem of faults in the pitch actuator. To address the wind-dependent behavior of turbines, a second controller is designed using the LIDAR sensor. In this configuration, LIDAR provides the look ahead wind information and generates a smooth scheduling signal to provide active robustness with respect to the changes in wind speed. Lastly, utilizing both the fault estimator and LIDAR, a 2-dimentional wind-dependent active fault tolerant controller is developed to control the wind turbine in region 3 of operation. The feasibility of the proposed ideas is verified in simulation. For this purpose, the US National Renewable Energy Laboratory's FAST code is used to model the 3-balded controls advanced research turbine. A discussion on practical considerations and ideas for future work are also presented.
    • Adsorption characteristics of polymer electrolyte membrane chemical degradation products and their impact on oxygen reduction reaction activity for platinum catalysts

      Richards, Ryan; Christ, Jason M.; Ciobanu, Cristian V.; Williams, S. Kim R.; Yang, Yongan; Yang, Yuan; Dinh, Huyen N. (Colorado School of Mines. Arthur Lakes Library, 2014)
      Developments in membrane-electrode assembly and stack technology have significantly improved the performance of polymer electrolyte membrane fuel cells; such that systematic studies focused on improving major challenges of overall cost and durability have become increasingly important. Consequently, interest in the examination of system derived impurities and their subsequent effects on performance durability has grown. Studies involving commercial polymer electrolyte membranes and model compounds have shown that when perfluorinated sulfonic acid (PFSA) membranes are exposed to hydroxyl radicals during fuel cell operating conditions, several chemical decomposition products can be generated. Along with losses in membrane conductivity and structural integrity, such PFSA membrane degradation products may also adsorb on the platinum based electrocatalyst, possibly leading to a loss in catalyst electrochemical surface area (ECA), oxygen reduction reaction (ORR) activity, or both. This work investigates adsorption characteristics and effects from model compounds in the forms of fluorinated organic acids, representing PFSA membrane chemical degradation species, on ECA and ORR activity for platinum based electrocatalysts including polycrystalline Pt, high surface area carbon supported Pt, and extended surface Pt. A reproducible method was developed in order to investigate surface coverage and adsorption properties due to carboxylate and sulfonate functional groups, fluorocarbon chain length, and model compound concentration. Data was obtained using a variety of electroanalytical techniques including mainly cyclic and linear sweep voltammetry, and electrochemical quartz crystal microbalance analysis. Information gleaned from this work shows that reversible adsorption occurs initially through carboxylate anions, while intermolecular forces involving fluorocarbon chain length and ether and sulfonate moieties play a secondary role in molecular ordering at the electrode surface. Reversible losses in Pt electrocatalyst activity in regards to the ORR were realized most heavily for diacid compounds (greater than 44% loss in kinetic current) containing both carboxylate and sulfonate functional groups, followed by longer chain fluorinated carboxylic acids (17% loss in kinetic current). Fluorinated sulfonic acids and shorter chain carboxylic acids showed little to no effects on ORR activity at the concentrations (0.001 mM - 1 mM) studied.
    • Advanced characterization techniques in understanding the roles of nickel in enhancing strength and toughness of submerged arc welding high strength low alloy steel multiple pass welds in the as-welded condition

      Liu, Stephen; Sham, Kin-Ling; Olson, D. L. (David LeRoy); Mishra, Brajendra; Findley, Kip Owen; Steele, John P. H.; Young, George (Colorado School of Mines. Arthur Lakes Library, 2014)
      Striving for higher strength along with higher toughness is a constant goal in material properties. Even though nickel is known as an effective alloying element in improving the resistance of a steel to impact fracture, it is not fully understood how nickel enhances toughness. It was the goal of this work to assist and further the understanding of how nickel enhanced toughness and maintained strength in particular for high strength low alloy (HSLA) steel submerged arc welding multiple pass welds in the as-welded condition. Using advanced analytical techniques such as electron backscatter diffraction, x-ray diffraction, electron microprobe, differential scanning calorimetry, and thermodynamic modeling software, the effect of nickel was studied with nickel varying from one to five wt. pct. in increments of one wt. pct. in a specific HSLA steel submerged arc welding multiple pass weldment. The test matrix of five different nickel compositions in the as-welded and stress-relieved condition was to meet the targeted mechanical properties with a yield strength greater than or equal to 85 ksi, a ultimate tensile strength greater than or equal to 105 ksi, and a nil ductility temperature less than or equal to -140 degrees F. Mechanical testing demonstrated that nickel content of three wt. pct and greater in the as-welded condition fulfilled the targeted mechanical properties. Therefore, one, three, and five wt. pct. nickel in the as-welded condition was further studied to determine the effect of nickel on primary solidification mode, nickel solute segregation, dendrite thickness, phase transformation temperatures, effective ferrite grain size, dislocation density and strain, grain misorientation distribution, and precipitates. From one to five wt. pct nickel content in the as-welded condition, the primary solidification was shown to change from primary delta-ferrite to primary austenite. The nickel partitioning coefficient increased and dendrite/cellular thickness was refined. Austenite decomposition temperatures into different ferrite products were also suppressed to refine the effective ferrite grain size with increasing nickel. Finally, dislocation density and strain increased and a more preferred orientation behavior was observed. At five wt. pct nickel, a precipitate in the form of MnNi3 or FeNi3 was observed. Its presence in both inter and intragranular regions enhanced strength and toughness by limiting the ferrite grain size and precipitation strengthening.
    • Alternative forming fluids for TRISO fuel kernel production

      King, Jeffrey C.; Baker, Michael P.; Braley, Jenifer C.; Gorman, Brian P.; Reimanis, Ivar E. (Ivar Edmund); Sellinger, Alan (Colorado School of Mines. Arthur Lakes Library, 2014)
      Current Very High Temperature Reactor designs incorporate TRi-structural ISOtropic (TRISO) particle fuel, which consists of a spherical fissile fuel kernel surrounded by layers of pyrolytic carbon and silicon carbide. An internal sol-gel process forms the fuel kernel by dropping a cold precursor solution into a column of hot trichloroethylene (TCE). The temperature difference drives the liquid precursor solution to precipitate the metal solution into gel spheres before reaching the bottom of a production column. Over time, gelation byproducts inhibit complete gelation and the TCE must be purified or discarded. The resulting mixed-waste stream is expensive to dispose of or recycle, and changing the forming fluid to a non-hazardous alternative could greatly improve the economics of kernel production. Selection criteria for a replacement forming fluid narrowed a list of ~10,800 chemicals to yield ten potential replacements. The physical properties of the alternatives were measured as a function of temperature between 25 degrees C and 80 degrees C. Calculated terminal velocities and heat transfer rates provided an overall column height approximation. 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane were selected for further testing, and surrogate yttria-stabilized zirconia (YSZ) kernels were produced using these selected fluids. The kernels were characterized for density, geometry, composition, and crystallinity and compared to a control group of kernels produced in silicone oil. Production in 1-bromotetradecane showed positive results, producing dense (93.8 %TD) and spherical (1.03 aspect ratio) kernels, but proper gelation did not occur in the other alternative forming fluids. With many of the YSZ kernels not properly gelling within the length of the column, this project further investigated the heat transfer properties of the forming fluids and precursor solution. A sensitivity study revealed that the heat transfer properties of the precursor solution have the strongest impact on gelation time. A COMSOL heat transfer model estimated an effective thermal diffusivity range for the YSZ precursor solution as 1.13x10[superscript -8] m[superscript 2]/s to 3.35x10[superscript -8] m[superscript 2]/s, which is an order of magnitude smaller than the value used in previous studies. 1-bromotetradecane is recommended for further investigation with the production of uranium-based kernels.
    • Alternatives to organic acid surface modification of ZnO for excitonic photovoltaics

      Furtak, Thomas E. (Thomas Elton), 1949-; Collins, Reuben T.; Brenner, Thomas M.; Gorman, Brian P.; Lusk, Mark T.; Boyes, Stephen G.; Olson, Dana C. (Colorado School of Mines. Arthur Lakes Library, 2014)
      Surface modification of metal oxides with molecular monolayers is an effective strategy for tuning interface properties in excitonic devices employing metal oxides as charge accepting and transport layers. The most commonly used attachment chemistries are acid/base reactions employing organic acids. The use of acid/base chemistries has presented a problem for one of the most commonly used and promising metal oxides in excitonic devices, zinc oxide (ZnO). ZnO is easily etched by even weak organic acids, leading to non-ideal monolayers and the accumulation of surface complexes during etching, which is particularly problematic for ZnO-based dye sensitized solar cells (DSSCs). Two ways to address this issue have been explored. The first approach is to employ a triethoxysilane (TES)-based covalent attachment scheme instead of an acid/base reaction for attaching modifier molecules. We demonstrate that dipolar mixed monolayers of phenyltriethoxysilane-based molecules tune the work function of ZnO and the performance of bulk heterojunction photovoltaic devices containing modified ZnO layers. This indicates these modifiers are effective for tuning interfacial electronic structure. The second approach is to investigate Zn[subscript 1-x]Mg[subscript x]O (ZnMgO) alloys in order to produce a more etch resistant material with similar electronic properties to ZnO. These alloys, when exposed to the prototypical modifier benzoic acid (BA), demonstrate a steady-state, macroscopic etch rate that decreases up to an order of magnitude (at 20% Mg) compared to ZnO. Infrared spectroscopic characterization of BA-modified ZnMgO indicates a monolayer of BA attaches to the ZnMgO surface nearly instantaneously and remains throughout etching. These results suggest that ZnMgO is a promising alternative material that may alleviate some of the problems with ZnO etching. However, for applications of this material as a substrate for dye sensitization, the initial etch rate, and not the steady-state rate, is really the quantity of interest. We investigated the initial etch rate of ZnMgO exposed to N3 dye (cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II)). We find the initial etch rate of ZnMgO increases with Mg content, in contrast to the steady-state etch rates observed for BA-treated ZnMgO. We also find that the primary products of etching are Zn-carboxylate products. From these results we propose a mechanism for the observed etch resistance.
    • Amplitude inversion of fast and slow converted waves for fracture characterization of the Montney Formation in Pouce Coupe field, Alberta, Canada

      Davis, Thomas L. (Thomas Leonard), 1947-; MacFarlane, Tyler L.; TSvankin, I. D.; Benson, Robert D.; Grossman, Jeff (Colorado School of Mines. Arthur Lakes Library, 2014)
      The Montney Formation of western Canada is one of the largest economically viable gas resource plays in North America with reserves of 449TCF. As an unconventional tight gas play, the well development costs are high due to the hydraulic stimulations necessary for economic success. The Pouce Coupe research project is a multidisciplinary collaboration between the Reservoir Characterization Project (RCP) and Talisman Energy Inc. with the objective of understanding the reservoir to enable the optimization of well placement and completion design. The work in this thesis focuses on identifying the natural fractures in the reservoir that act as the delivery systems for hydrocarbon flow to the wellbore. Characterization of the Montney Formation at Pouce Coupe is based on time-lapse multicomponent seismic surveys that were acquired before and after the hydraulic stimulation of two horizontal wells. Since shear-wave velocities and amplitudes of the PS-waves are known to be sensitive to near-vertical fractures, I utilize isotropic simultaneous seismic inversions on azimuthally-sectored PS[subscript 1] and PS[subscript 2] data sets to obtain measurements of the fast and slow shear-velocities. Specifically, I analyze two orthogonal azimuths that are parallel and perpendicular to the strike of the dominant fracture system in the field. These volumes are used to approximate the shear-wave splitting parameter that is closely related to crack density. Since crack density has a significant impact on defining the percolation zone, the work presented in this thesis provides information that can be utilized to reduce uncertainty in the reservoirs fracture model. Isotropic AVO inversion of azimuthally limited PS-waves demonstrates sufficient sensitivity to detect contrast between the anisotropic elastic properties of the reservoir and is capable of identifying regions with high crack density. This is supported by integration with spinner production logs, hydraulic stimulation history of the field, and microseismic. Results also show significant fracture network heterogeneity that is not typically accounted for in engineering-driven development despite a strong link to production. The main value of this work lies in the integration of fracture characterization with preceding RCP theses that defined the geomechanical model and composition of the reservoir at Pouce Coupe. Geophysical attributes that relate to the composition and natural fractures enable a more complete understanding of the reservoir and indicate that a successful well is dependent on both the hydrocarbon storage capacity of the matrix and a large permeable network of natural fractures.
    • Analysis of diesel particulate matter using electron monochromator-mass spectrometry, bacterial identification using mass spectrometry and lateral flow immunochromatography, and detection of levamisole as a cutting agent in patients using cocaine

      Voorhees, Kent J.; Jensen, Kirk Richard; Posewitz, Matthew C.; Marr, David W. M.; McCormick, Robert L.; Eberhart, Mark E. (Colorado School of Mines. Arthur Lakes Library, 2014)
      Three studies and one review involving analytical mass spectrometry and one article on rapid bacterial diagnostics are presented herein. Electron monochromator-mass spectrometry (EM-MS) literature is presented outlining the development history and relevant analytical applications including nitro compounds in cigarette smoke, resonance energy studies, explosives, and bacterial identification. Diesel particulate matter and the effect of antioxidant fuel additives on nitro polycyclic aromatic production during diesel engine operation was investigated using EM-MS. Results showed a strong correlation between production of 2,6-di-tert-butyl-4-nitrophenol (DBNP) and the addition of two antioxidant precursors to the fuel prior to combustion. No correlations were observed between DBNP production and engine load or speed. Results indicate that the role of fuel additives in combustion byproducts must be carefully considered. When using CaO as a matrix-replacement in matrix-assisted laser desorption/ionization mass spectrometry, fatty acids are cleaved from phospholipids in situ by laser-induced pyrolysis. Ten bacterial genera were investigated using CaO as a matrix. Fatty acid profiles were observed and exported for statistical analysis. Principal components analysis of fatty acid profiles revealed distinct separation of bacterial genera. Cross-validation resulted in greater than 94% correct assignment. Future applications could provide clinicians a rapid and reliable method of bacterial detection. Outbreaks of infectious bacteria and concerns over bioterrorism have increased the demand for methods of rapidly and easily detecting bacteria. A lateral flow immunoassay (LFI) device was developed to detect Bacillus anthracis indirectly by using gamma phage amplification. Phage-based LFI detection of B. anthracis Sterne was consistently observed within four and as little as two hours of the onset of phage amplification with a threshold sensitivity of 2.5 x 10[superscript 3] cfu/mL. Ease and speed of the device could find application in the field by military personnel. Finally, individuals admitted to a hospital following cocaine use showed symptoms of levamisole poisoning. Levamisole, an antihelminthic used in veterinary science and a known lacing/cutting agent for cocaine, was detected in urine samples from these patients. Tissue and blood samples were also analyzed, but no concentration was detected. While no direct correlation could be made between patient symptoms and levamisole, its presence in their urine is a strong indication that the cocaine had been cut/laced with levamisole.
    • Analytical methods for characterizing oil and gas development and production waste streams: a critical review and collaborative inter-laboratory comparison

      Cath, Tzahi Y.; Yaffe, Bethany Grace Marie; Higgins, Christopher P.; Cohen, Ronald R. H. (Colorado School of Mines. Arthur Lakes Library, 2014)
      As the oil and gas industry expands in the United States, managing the high volume waste streams generated during development and production becomes increasingly crucial to the preservation of ecosystem and human health. Accurate characterization is essential to ensure proper treatment and disposal. Therefore, a collaborative inter-laboratory comparison was performed using methods applied to oil and gas development and production wastewaters. Four samples were analyzed using five different methods. The samples included raw fracturing flowback, treated fracturing flowback, raw produced water, and treated produced water. The methods used to characterize these waters were EPA Method 300.0, EPA Method 200.7, EPA Method 200.8, SW 846 Method 6010C, and SW 846 Method 8015B. The mean, standard deviation, and relative standard deviation of the results from this inter-laboratory comparison were compared to the mean, standard deviation, and relative standard deviation found in each of the EPA methods validation data. This comparison elucidated the variation resulting from the application of the EPA methods to the oil and gas development and production wastewater matrices.
    • Applications of temperature modeling and distributed temperature sensing (DTS) in hydraulic fracture stimulation diagnostics

      Tutuncu, Azra; McCullagh, Christopher Lawrence; Eustes, Alfred William; Hoffman, B. Todd; Sonnenberg, Stephen A.; Davis, Thomas L. (Thomas Leonard), 1947- (Colorado School of Mines. Arthur Lakes Library, 2014)
      In unconventional oil and gas wells, the key to economic production is the success of the hydraulic fracture stimulation. Determining the effectiveness of the stimulation is often difficult. New technologies can characterize the hydraulic fractures produced from the stimulation. Among these is distributed temperature sensing (DTS). DTS allows for continuous temperature measurements along the wellbore, and through the use of temperature modeling, DTS may be used to diagnose the effectiveness of hydraulic fracture stimulations both during the treatment (real-time) and after the well has been shut in (warm-back). In this study temperature models were used to simulate the wellbore temperature change both during the hydraulic fracture stimulation treatment and after the treatment has been completed. During the treatment, DTS and temperature modeling allows for the tracking of fluid throughout the wellbore. This may be used to determine which perforated zones receive the most stimulation fluid and can also dictate how and where fluid leaves the wellbore. Published temperature models were used to simulate wellbore temperature changes in Eagle Ford study wells. The published models were coded using VBA in order to create a numerical simulation. The numerical model was compared to simplified analytical solutions and an ideal time step and grid size were determined. Several cases were tested using different fluid distributions across the perforated zones. In lieu of DTS data, microseismic was used to assist in setting the parameters of the temperature simulation. Due to high pump rates, small perforated zones, and close perforation spacing, real-time evaluation of hydraulic fracture stimulation treatments in the Eagle Ford study wells resulted in ambiguous results. As a result, a different type of temperature model was derived and implemented in the study, the warm-back temperature model. The derivation of the warm-back model is similar to that of the real-time model but is much simpler and uses different boundary conditions. Like the real-time model, the purpose of the warm-back model is to determine fluid placement along the wellbore into the perforated zones. In this study fluid placement was used to directly determine fracture length. The benefit of the warm-back model is that it is not directly a function of pump rates or completions. As a result, the warm-back model allows for greater understanding of the hydraulic fractures than the real-time model. Microseismic was again used to adjust parameters affecting the temperature simulation.
    • Approach to beneficiation of spent lithium-ion batteries for recovery of materials, An

      Mishra, Brajendra; Marinos, Danai; Anderson, Corby G.; Spiller, D. Erik (Colorado School of Mines. Arthur Lakes Library, 2014)
      Lithium ion batteries are one of the most commonly used batteries. A large amount of these have been used over the past 25 years and the use is expected to rise more due to their use in automotive batteries. Lithium ion batteries cannot be disposed into landfill due to safety reasons and cost. Thus, over the last years, there has been a lot of effort to find ways to recycle lithium ion batteries. A lot of valuable materials are present in a lithium ion battery making their recycling favorable. Many attempts, including pyrometallurgical and hydrometallurgical methods, have been researched and some of them are already used by the industry. However, further improvements are needed to the already existing processes, to win more valuable materials, use less energy and be more environmentally benign. The goal of this thesis is to find a low-temperature, low-energy method of recovering lithium from the electrolyte and to develop pathways for complete recycling of the battery. The research consists of the following parts: Pure LiPF6 powder, which is the electrolyte material, was characterized using x-ray diffraction analysis and DSC/TGA analysis. The LiPF6 powder was titrated using acid (HCl, HNO3, H2SO4), bases (NH4OH) and distilled water. It was concluded that distilled water was the best solvent to selectively leach lithium from lithium-ion batteries. Leaching conditions were optimized including time, temperature, solid/liquid ratio and stirring velocity. All the samples were tested using ICP for chemical composition. Because leaching could be performed at room temperature, leaching was conducted in a flotation machine that was able to separate plastics by creating bubbles with no excess reagents use. The solution that contained lithium had to be concentrated more in order for lithium to be able to precipitate and it was shown that the solution could be concentrated by using the same solution over and over again. The next set of experiments was composed of battery shredding, steel separation by hand magnet, leaching with distilled water and sizing using wet sieving. Every fraction was sent to rare-earth rolls separation and eddy current separation. A size distribution analysis was conducted and the fractions were analyzed using ICP .
    • As-cast uranium-molybdenum based metallic fuel candidates and the effects of carbon addition

      Porter, Jason M.; Mishra, Brajendra; Blackwood, Van Stephen; Olson, D. L. (David LeRoy); Liu, Stephen; Mustoe, Graham G. W.; Miller, Hugh B. (Colorado School of Mines. Arthur Lakes Library, 2014)
      The objective of this research was to develop and recommend a metallic nuclear fuel candidate that lowered the onset temperature of [gamma] phase formation comparable or better than the uranium-10 wt. pct. molybdenum alloy, offered a solidus temperature as high or higher than uranium-10 wt. pct. zirconium (1250 degrees C), and stabilized the fuel phase against interaction with iron and steel at least as much as uranium-10 wt. pct. zirconium stabilized the fuel phase. Two new as-cast alloy compositions were characterized to assess thermal equilibrium boundaries of the [gamma] phase field and the effect of carbon addition up to 0.22 wt. pct. The first system investigated was uranium- x wt. pct. M where x ranged between 5-20 wt. pct. M was held at a constant ratio of 50 wt. pct. molybdenum, 43 wt. pct. titanium, and 7 wt. pct. zirconium. The second system investigated was the uranium-molybdenum-tungsten system in the range 90 wt. pct. uranium - 10 wt. pct. molybdenum - 0 wt. pct. tungsten to 80 wt. pct. uranium - 10 wt. pct. molybdenum - 10 wt. pct. tungsten. The results showed that the solidus temperature increased with increased addition of M up to 12.5 wt. pct. for the uranium-M system. Alloy additions of titanium and zirconium were removed from uranium-molybdenum solid solution by carbide formation and segregation. The uranium-molybdenum-tungsten system solidus temperature increased to 1218 degrees C at 2.5 wt. pct. with no significant change in temperature up to 5 wt. pct. tungsten suggesting the solubility limit of tungsten had been reached. Carbides were observed with surrounding areas enriched in both molybdenum and tungsten. The peak solidus temperatures for the alloy systems were roughly the same at 1226 degrees C for the uranium-M system and 1218 degrees C for the uranium-molybdenum-tungsten system. The uranium-molybdenum-tungsten system required less alloy addition to achieve similar solidus temperatures as the uranium-M system.
    • Aspects of time-lapse electrical resistivity monitoring in geotechnical and reservoir problems

      Li, Yaoguo; Putman, Brent D.; Batzle, Michael L.; Hale, Dave, 1955-; Nabighian, Misac N. (Colorado School of Mines. Arthur Lakes Library, 2014)
      Internal erosion can be present in almost any environment in which fluid flows through a rock matrix. In almost all cases this phenomenon is a problem to be avoided. Internal erosion weakens the rock structure, which can cause collapse of the surrounding matrix. In the geotechnical field, this is most common with earthen dams and levees. The consequence of internal erosion in an oil and gas reservoir setting is to create a high-permeability link between injection and production wells, by-passing resource containing volumes of the reservoir. In this thesis, I present feasibility studies to examine the effectiveness of electrical resistivity tomography (ERT) for monitoring both fluid flow and the resultant internal erosion. This is conducted in both the laboratory and reservoir scales. Because the success of ERT is highly dependent on the configuration of electrodes, significant time is spent on developing configurations that image internal erosion while also limiting the number of data required. This work gives evidence that ERT can have beneficial use in the geotechnical monitoring scenario. The feasibility study for the small-scale geotechnical experiment on internal erosion shows that a 10 cm diameter sample can be imaged effectively when the electrode configuration is properly designed. This feasibility study is further confirmed through a data set collected in the laboratory. This experiment produced sufficient results in terms of the model recovered through inversion. The feasibility study evaluating ERT in a reservoir setting shows that the monitoring target is the total 410 m long swept zone, rather than the small fractures, due to low signal strength from the fractures. The capability of ERT in the reservoir scenario depends on the degree of internal erosion and the electrode configuration used to take measurements. If data can be collected in boreholes in close proximity to the swept zone, then ERT has a potential beneficial application in monitoring fluid flow and associated fractures.
    • Automatic multicomponent image registration

      Hale, Dave, 1955-; Compton, Stefan; Young, Terence K.; Rüger, Andreas (Colorado School of Mines. Arthur Lakes Library, 2014)
      Multicomponent seismic images are composed of different combinations of downgoing and upgoing wavefields. Each wave mode has different propagation velocity and polariza- tion direction and thus carries unique, direction-dependent information about the subsurface. Differences in propagation velocity cause events in converted- or shear-wave images to appear at later times than the compressional-wave image counterpart. Reflectivities are different for each wave mode and therefore, multicomponent images are not related simply by time shifts. These complications historically required that the alignment, also called registration of corresponding image features be done manually, a tedious process. This thesis devel- ops an approach to automatically register multicomponent images using a smooth dynamic warping algorithm that can be accurate with respect to problems unrelated to time shifts. Interval Vp/Vs ratios can be estimated from derivatives of time shifts that align reflections in multicomponent images, and these Vp/Vs ratios may be used to assess the accuracy of the automatic registration process. To improve the accuracy of estimated time shifts and Vp/Vs ratios, we automatically construct a coarse lattice of points located on reflections with high amplitudes, and then estimate time shifts at only those points. By adjusting the coarseness of the lattice, we trade off resolution of changes in Vp/Vs with increased accuracy in Vp/Vs estimates. The result is an efficient, robust, and automatic method for multicomponent image registration.
    • Automatic simultaneous multiple-well ties

      Hale, Dave, 1955-; Munoz, Andrew; Young, Terence K.; Batzle, Michael L. (Colorado School of Mines. Arthur Lakes Library, 2014)
      Well logs, measured in depth, must be tied to seismograms, processed in time, using a time-depth function. Well ties are commonly computed using manual techniques, and are therefore prone to human error. I first introduce an automatic single-well tie method that uses smooth dynamic time warping to compute time shifts that align a synthetic seismogram with a seismic trace. These time shifts are constrained to be smoothly varying. I also show that these well ties, in my example, are insensitive to the complexity of my synthetic seismogram modeling. Tying multiple wells compounds errors in single well ties, and maintaining consistency among multiple single well ties is difficult. I introduce an automatic approach to tying multiple wells that improves consistency among well ties. I first model synthetic seismograms for each well. I then create a synthetic image by interpolating the synthetic seismograms between the wells and along seismic image structure. I use smooth dynamic image warping to align the synthetic image to the seismic image and compute updated time-depth functions for each well. I then interpolate the updated time-depth functions between the wells, and map the time-migrated seismic image to depth.
    • Benders decomposition: an integer-programming extension with further computational enhancements

      Newman, Alexandra M.; Wood, R. Kevin; Tarvin, David Antony; Coffey, Mark; Mehta, Dinesh P.; Turner, Cameron J. (Colorado School of Mines. Arthur Lakes Library, 2014)
      We extend Benders decomposition in two ways. We begin by introducing a new integer Benders decomposition algorithm (IBDA) that solves pure integer programs (IPs). IBDA solves a mixed-integer relaxation of the IP by Benders decomposition and then conducts a type of local search to identify promising solutions to the original problem. IBDA's key contributions are the local-search technique and a novel use of solution-elimination constraints. We prove IBDA's correctness and demonstrate that the algorithm solves certain IPs faster than other available techniques. Slow Benders master-problem solution times can limit IBDA's effectiveness, however. To ameliorate this problem, we therefore develop a "Benders decomposition algorithm using enumeration to solve master problems" (BDEA). BDEA stores objective-function values for all master-problem solutions, and then solves the subsequent master problem by comparing the incumbent value to the value of the most recent Benders cut for every feasible solution. Using enumeration, master-problem solution times remain constant even as the number of Benders cuts increases. We demonstrate BDEA's performance using a stochastic capacitated facility-location problem. Computational tests show that BDEA can reduce average solution times by up to 74% compared to a standard BDA implementation.
    • Beneficiation of plasma display panels

      Taylor, Patrick R.; Esquibel, Matthew; Anderson, Corby G.; Mishra, Brajendra (Colorado School of Mines. Arthur Lakes Library, 2014)
      A literature review, thermodynamics, and experimental testing were used to develop a beneficiation method for plasma display panels. The proposed process includes cutting the adhered glass, separating the front and back glass, acid leaching the glass panels separately, precipitating indium hydroxide, and precipitating rare earth oxalates. This process has the advantage of not requiring the glass to be crushed. Combining the front and back glass into one leaching stage followed by a two-stage precipitation is an option, but further test work is required. It was found that the best leach conditions for the ITO powder during testing was a temperature of 90°C, agitation rate of 600 rpm, 2.0054 g/L, 1M H2SO4, and 4 hours of leaching time. 99% of the indium was extracted at a grade of 96%. Leaching results suggest the process is controlled by the chemical reaction. The indium hydroxide precipitation was found to be optimal at a pH of 6, agitation rate of 400rpm, temperature of 25°C, 84 g/L NaOH, and a precipitation time of 90 minutes.96% of the indium was recovered as a hydroxide at a grade of 97%. The acidic leaching of the rare earth phosphor powder was found to be best at a temperature of 70°C, agitation rate of 600 rpm, 1M H2SO4, 2.5g/L, and 4 hours of leaching time. 99% of the REES were extracted with these parameters. Leaching results suggest the process is controlled by the chemical reactions. The parameters were then used on the phosphor glass and extracted 69% of the REEs at a grade of 10%. Rare earth oxalate precipitation results showed that it was possible to recover 98% of the REEs. Combined leaching experiments showed promise in extracting both indium and the REEs, but further work is required. A two-stage precipitation was attempted on the combined leach solution. The first stage is an indium hydroxide precipitation and the second stage is a rare earth oxalate precipitation. The precipitation results were encouraging, but a high indium concentration is required for the first precipitation stage to be selective. Further work is required on the two-stage precipitation parameters.
    • Biologically active filtration for treatment of produced water and fracturing flowback wastewater in the O&G industry

      Cath, Tzahi Y.; Freedman, Daniel E.; Higgins, Christopher P.; Spear, John R. (Colorado School of Mines. Arthur Lakes Library, 2014)
      Sustainable development of unconventional oil and gas reserves, particularly tight oil, tight gas, and shale gas, requires prudent management of water resources used during drilling, well completion, and production activities. Economic viability of unconventional resource de-velopment can be attributed to technical advancements in horizontal drilling and hydraulic frac-turing, both of which are water-intensive operations. On average, 2 to 5 million gallons of water are required for multistage hydraulic fracturing of a single horizontal well. This raises concerns about freshwater acquisition and management of the wastewater generated. The associated risks to water resources are of major interest and concern to water utilities, stakeholders, and environ-mentalists. Mitigation of such risks can be achieved through a comprehensive water management plan that integrates robust treatment technologies aimed at recovering water for recycling in field operations. Recycling of flowback and produced water is presently becoming a more widely applied management practice, as it protects freshwater resources by eliminating surface water discharge and reducing demand on high quality sources. Recycling is potentially cost-effective because it often requires a lower level of treatment than would surface water discharge or other beneficial reuse application. Yet, significant challenges remain in rendering these waste streams amenable for reuse. Reduction of organic matter has been a notable wastewater treatment engineering chal-lenge and has limited practical opportunities for reuse. This research focuses on harnessing the propensity of microorganisms for biodegradation of organic carbon present at high concentrations in fracturing flowback and produced water. Bench-scale and pilot-scale biofiltration systems were investigated to determine adaptability of a specific biofilm and measure biodegradation of organic carbon at different operating conditions. The biologically active media was gradually acclimated to a produced water stream from the Piceance Basin. Following the successful conditioning and acclimation, up to 90% DOC removal and 80% COD removal was achieved. Results from the performance evaluation demonstrated scalability and flexibility of the system to maintain treatment efficiency, as well as the impacts of variable operating conditions.