Browsing by Author "Omur-Ozbek, Pinar, committee member"
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Item Open Access A comparison of electrocoagulation and chemical coagulation treatment effectiveness on frac flowback and produced water(Colorado State University. Libraries, 2015) Hutcherson, John Ryan, author; Carlson, Ken, advisor; Omur-Ozbek, Pinar, committee member; Stednick, John, committee memberDevelopment and production of tight shale for crude oil and natural gas is increasing rapidly throughout the United States and especially in the Wattenberg field of Northern Colorado. Hydraulic fracturing is used to stimulate the shale formation, which allows previously trapped oil and gas to flow to the surface. According to Goodwin (2013), approximately 2.8 million gallons of water are required to hydraulically fracture a horizontal well. Freshwater makes up the vast majority of water used to create these fracturing fluids with a small portion coming from recycling of previously used fracturing fluid. In a semi-arid climate such as Northern Colorado, there are multiple demands for freshwater, often exceeding the supply. Once a well is fractured, water flows back to the surface along with the targeted oil and gas. This fluid is typically referred to as flowback or produced water. In some areas around the United States as much as 10 barrels of water flows to the surface for every barrel of oil recovered. For the purposes of this research, flowback is defined as water that flows to the surface within the first 30 days after fracturing. After fracturing, up to 71% of the water (produced water) used to fracture the well flows back to the surface along with oil and gas, with approximately 27% flowing back in the first 30 days (Bai et al, 2013). The flowback and produced water is currently being disposed of either by deep underground injection or in evaporation ponds. There has been very little effort to capture, recycle, and reuse this flowback or produced water as it has traditionally been considered a waste product. Due to the limited freshwater supply in Colorado, recycling and reuse should be explored in greater detail and with a sense of urgency. The ultimate goal for the oil and gas industry should be to recycle and reuse 100% of flowback and produced water in the creation of hydraulic fracturing fluid for other production wells, creating a closed-loop system. Before flowback and produced water can be reused, treatment of the water is required. Treatment for reuse typically consists of removal of solids, organic compounds, and some inorganic ions. Historically, chemicals have been the dominant method used for coagulation to remove solids, as they are readily available and in many cases can be cheaper than other methods. Electrocoagulation (EC) is now also being considered as a produced water treatment method. EC involves running electric current across metal plates (sacrificial anodes) in a solution, which creates an in situ coagulant dose (Emamjomeh and Sivakumar 2008). There is a time component to water quality changes over the life of a well. Early flowback typically has higher concentration of aluminum, solids, and total organic carbon (TOC) as it is influenced mostly by the makeup of the fracturing fluid. At some point around the 30-day mark, a transition in water quality begins. The formation or connate water seems to have a greater influence on water quality than does the fracturing fluid. Treatment seems to correlate to the changing water quality, as treatment is less effective on the early flowback compared to produced water. TOC and low ionic strength may be the reason early flowback is more difficult to treat. Also, chemical coagulation (CC) is more effective than EC at removing TOC and aluminum in early flowback water compared to EC, while EC is more effective at removing iron. However, both treatments are effective after day 27.Item Open Access Characterization and treatment of produced water from Wattenberg oil and gas wells fractured with slickwater and gel fluids(Colorado State University. Libraries, 2014) Sick, Bradley A., author; Carlson, Kenneth, advisor; Omur-Ozbek, Pinar, committee member; Bradley, Thomas, committee memberTreatment of produced water for reuse as a fracturing fluid is becoming an increasingly important aspect of water management surrounding the booming unconventional oil and gas industry. Understanding variation in water quality due to fracturing fluid and produced water age are fundamental to choosing an effective treatment strategy. This study involves the collection and analysis of produced water samples from three wells in the Wattenberg Field, located in northeast Colorado, over a 63-day study period (15 sampling events). One well was fractured with a cross-linked gel fluid, one with a slickwater fluid, and one with a hybrid of both fluids. Extensive water quality characterization was conducted on each sample to understand the impact of fracturing fluid type on temporal water quality trends. The greatest impact observed was that total organic carbon (TOC) concentrations were significantly higher in produced water samples from the wells fractured with the gel and hybrid fluids (943 to 1,735mg/L) compared to the well fractured with the slickwater fluid (222 to 440 mg/L). Total dissolved solids (TDS) concentrations, as well as many of the component inorganics that make up TDS, were fairly consistent among the three wells. TDS concentrations at each well increased with time from roughly 18,000 mg/L at day 1 to roughly 30,000 mg/L at day 63. Jar testing was conducted on collected samples to understand the variability in chemical coagulation/flocculation treatment due to type of fracturing fluid and well age. For the sampled wells, it was found that chemical coagulation can successfully reduce the turbidity of produced waters from wells fractured with both slickwater and gel fluids immediately after the start of production. The coagulant demand for produced waters from wells fractured with gel fluids was found to be roughly 25 to 300 % higher than that for wells fractured with slickwater fluids. The coagulant demand of produced water from each well was found to decrease with the age of the well. Additional laboratory characterization techniques were conducted on a subset of samples in order to better understand the makeup of organic compounds in produced water, including an analysis of the distribution of the volatile portion of solids, a TOC size analysis, and an analysis of organic subcategories. It was found that the majority of organic compounds in produced water samples are smaller than 0.2 µm, and that the relatively small portion that is larger than 1.5 µm contributes significantly to the predominantly volatile total suspended solids (TSS) load. Carbohydrates were found to be the largest contributor to the overall organic compound load in early produced waters from wells fractured with gel fluids; petroleum hydrocarbons were found to be the largest contributor from wells fractured with slickwater fluids. Chemical coagulation was found to reduce TOC concentrations by roughly 20%, independent of this difference in makeup.Item Open Access Characterization of solids in produced water from wells fractured with recycled and fresh water(Colorado State University. Libraries, 2015) Li, Gen, author; Kenneth, Carlson H., advisor; Omur-Ozbek, Pinar, committee member; Bradley, Thomas H., committee memberWater management is a central issue in oil and gas development. Hydraulic fracturing applied in unconventional tight oil and gas development requires large amounts of water, and the wastewater that results after production--containing high levels of organic and inorganic matter-- usually is disposed of through deep well injection. A new approach reuses this produced water as part of subsequent fracturing fluid, an alternative that could significantly reduce both fresh water demand and the cost associated with deep well injection. However, produced water must be treated prior to reuse, to remove most of the suspended solids and multivalent ions that would otherwise cause scale or clogging problems. Understanding the amount and composition of solids in produced water is crucial in achieving optimized treatment and reuse. This study targeted the characterization, both qualitatively and quantitatively, of the solids in produced water from oil and gas operations and the comparison of solids from wells fractured with fresh water and recycled water. Samples were collected from five wells at the Crow Creek and Chandler State pads in the Wattenberg field of Northern Colorado. Wells in the same pad were fractured either with fresh surface water only or with water blended with some portion of recycled produced water. Gravimetric analyses of dissolved and suspended solids were performed, and particle size distributions of suspended solids were measured. Suspended solids also were isolated and characterized with X-ray photoelectron spectroscopy (XPS). Gravimetric analyses showed that total dissolved solids (TDS) averaged about 24000 mg/L and 17000 mg/L for Crow Creek and Chandler State wells, respectively. Total suspended solids (TSS) concentrations were much lower, measuring 550 and 260 mg/L for the two pads. About 9 to25 percent of TDS was volatile and 88 to 99 percent of TSS was highly volatile. Particle sizes were high during first few days of production and then stabilized at about 400 nm and 900 nm for wells on the Crow Creek and Chandler State pads, respectively. At the Crow Creek pad, particle sizes were smaller and mono-distributed in produced water samples collected during the first week of production from the well fractured with recycled water, suggesting that the recycled water was more compatible with shale formation and that wells fractured with recycled water tend to clean out faster. XPS tests for isolated suspended solids showed the presence of major elements such as oxygen, carbon, and silicon, along with minor elements such as calcium, magnesium, zirconium, iron, and others. Core-level scanning confirmed that the isolated suspended solids were mainly composed of carbonate based minerals and metal oxides; several iron compounds with different valences were also found in the produced water samples.Item Open Access Determining the effect of primer mismatches on quantitative PCR accuracy and developing guidance for design of primers with sequence variations(Colorado State University. Libraries, 2012) Ledeker, Brett Michael, author; De Long, Susan K., advisor; Omur-Ozbek, Pinar, committee member; Reardon, Kenneth F., committee memberAlthough quantitative PCR (qPCR) is a powerful tool for investigating environmental systems, target gene sequences for organisms of interest often are not well known, which has resulted in few reliable primers for many applications. Additionally, the sequences of target genes found in diverse strains often contain sequence variations, and therefore, primer sets containing single or multiple primer-template mismatches are common. However, the detrimental impact of these mismatches on quantification accuracy and amplification efficiency has not been investigated thoroughly. Thus, the research objectives of this study were to elucidate the relationships between primer mismatches and the accuracy of qPCR assays and to develop guidance for designing primers targeting genes displaying sequence variations. The pcrA gene (encoding perchlorate reductase) from Dechloromonas agitata was used as a model system for this study, and a linearized plasmid containing the cloned pcrA gene was used as the qPCR template. A large number of pcrA primers (16 forward and 16 reverse) were designed containing from zero to three mismatches at various locations. Combinations of primers were tested to determine the impact of mismatches on the amplification efficiency, the threshold cycle (CT), and the quantification accuracy. Quantification accuracy was calculated as the percent detected by dividing the quantity measured with mismatch primers by the quantity measured with perfect match primers and multiplying by 100. Single mismatches at the 3' end resulted in quantification accuracies as low as ~3%, and single mismatches at the 5' end resulted in quantification accuracies as low as ~33%. Double and triple mismatches at the 5' resulted in quantification accuracies as low as ~17% and ~2%, respectively. Reductions in quantification accuracy correlated with increases in CT induced by mismatches but not with changes in amplification efficiency. Combining mismatched forward and reverse primers had an impact equivalent to the combined effect of the individual mismatch primers. Analogous qPCR tests were run with three other model genes: celS (encoding family 48 cellulase), C23O (encoding catechol dioxygenase, involved in toluene degradation), and hydA (encoding periplasmic hydrogenase, involved in fermentation). Primers were artificially designed to contain mismatches with these target genes, and results demonstrated that single or double mismatches can have a substantial detrimental impact on quantification accuracy in a broad range of systems. The results of this study indicate that caution must be taken to avoid mismatches when designing qPCR primers targeting genes with sequence variations and the findings serve to guide future design of primers for accurately quantifying genes in environmentally relevant systems.Item Open Access Encounters, norms, crowding: an application of the normative theory and methods in Turkey(Colorado State University. Libraries, 2017) Bingül, Meryem Bihter, author; Donnelly, Maureen P., advisor; Vaske, Jerry J., advisor; Bright, Alan, committee member; Omur-Ozbek, Pinar, committee memberNational parks attract millions of visitors a year due to their natural and cultural importance (Manning, 2007). The number of visits to national parks has been rapidly increasing around the world (Manning & Krymkowski, 2010). The high level of visitation to these areas has generated concerns about sustaining appropriate levels of social and environmental impacts. Growing demand for access and participation in recreational activities in national parks can damage both the ecological integrity of the environment, as well as reducing the quality of visitor experiences. The quality of visitor experiences must be maintained at a high level for national parks to contribute their full potential to society (Manning, 2002). In the literature, the quality of the visitor experience has been addressed through the concept of carrying capacity (Manning, 2007). In the United States, several planning frameworks have been developed and applied for National Parks relating to carrying capacity such as Limits of Acceptable Change (LAC), Visitor Impact Management (VIM), and Visitor Experience and Resource Protection (VERP). These frameworks share a common idea of identifying and establishing quantitative impact indicators and standards. National Parks in Turkey, however, have no such framework for monitoring the quality of both the natural environment and the visitor experience. Research on these issues is also very limited. The primary purpose of this dissertation is to examine the applicability of normative theory and methods in Turkey by addressing the interrelationships of visitor encounter norms and perceptions of crowding, resulting in the identification of appropriate indicators and standards of quality for management of the country's national parks. This dissertation presents three manuscripts designed to contribute this area of inquiry. The first chapter focuses on one of the structural characteristics of norms (e.g. norm prevalence) and methodological considerations that influence norm prevalence. The following research questions examined in this manuscript: first, what percent of visitors will report a norm in a given setting (Rocky Mountain National Park-ROMO)? Does the survey response format influence norm prevalence? Among those reporting a norm, to what extent do normative evaluations differ between two different response formats (e.g. closed and semi-open format)? Results indicated that norm prevalence is higher when respondents are asked to circle a number from range of values presented on the survey (closed format) as opposed to writing in a number (semi-open format). Among those reporting a norm, the average norm tolerance levels for the closed and semi-open question formats are equivalent across all specific locations. This work demonstrate that survey response format influence norm prevalence (percentage of individuals reporting a norm) and the numerical value of the reported norm. The second chapter examines the generalizability of the research findings from the ROMO study to Dilek Peninsula National Park-DPNP, in Turkey. The same research questions are asked in this second manuscript. First, what percent of visitors will report a norm in DPNP? Second, among those reporting a norm, to what extent do normative evaluations differ between semi-open and closed response formats? Results demonstrated that encounter norm prevalence (i.e., the percent of individuals who could specify a norm) is higher for the closed format of the survey as compared to the semi-open version. In addition, among those reporting a norm, the average tolerance levels were statistically higher in the semi-open format. The third chapter focuses on relationships among encounters, norms, and crowding for both settings ROMO and DPNP examining following research questions; First, what are visitor's norms regarding encounters with others at the site? Second, what proportion of visitors encounter fewer or more than their norm? Third, if they encounter fewer or more visitors than their norm, how does this affect visitors' perception of crowding? Fourth, to what extent does perceived crowding differ between ROMO and DPNP? Lastly, to what extent does the country of origin influence perceived crowding? Findings shows, in both settings, when visitors encountered more people than their norm, perceived crowding was higher compared to when individuals encountered less than their norms. The findings also showed that Turkish respondents felt more crowded than American visitors. In total, this dissertation is intended to provide a deeper look at the applications of normative theory and methods between two countries the United States and Turkey to contribute management of parks and outdoor recreation.Item Open Access Environmental impacts of oil and gas activities in northern Colorado(Colorado State University. Libraries, 2018) Li, Huishu, author; Carlson, Kenneth H., advisor; Sharvelle, Sybil, committee member; Omur-Ozbek, Pinar, committee member; Liu, Jiangguo, committee memberThe surge of shale oil and gas exploration and production in the United States is driven by the application of horizontal drilling and hydraulic fracturing which require and generate massive amount of water during the production of crude oil and natural gas. Since 2010, shale oil and gas production from northern Colorado (Wattenberg field) has increased rapidly due to the rich deposit of oil and natural gas in the shale formation, which also raises a lot of concerns over its potential environmental impacts on groundwater and air. To understand the contaminant transport mechanisms, identify the sources of contamination caused by oil and gas operations, and detect the contamination associated with drilling and fracturing activities will help improve the environmental and economic sustainability of shale-gas extraction. Therefore, our research focuses on the following topics: 1, determine the contaminants due to horizontal drilling and hydraulic fracturing; 2, study on the subsurface transport and distribution of contaminants related to oil and gas activities in groundwater; 3, design and evaluate a regional groundwater monitoring network to detect the contamination events.Item Open Access Facies distribution, its implications for climate signals, and hydrocarbon potential of the Permian Lyons Sandstone, Front Range Basin, northern Colorado, USA(Colorado State University. Libraries, 2016) Kendigelen, Oguzhan, author; Egenhoff, Sven, advisor; Stright, Lisa, committee member; Omur-Ozbek, Pinar, committee memberThe Permian Lyons Formation consists of mostly fine- to medium-grained sandstones with minor silt- and mudstone intercalations. The formation shows six siliciclastic facies that are grouped into two Facies Associations: Facies Association 1 consists of high-angle cross-laminated sandstones (Facies 1), low-inclined cross-laminated sandstones (Facies 2), horizontally-laminated sandstones (Facies 3), and chaotically-bedded to folded sandstones (Facies 4), while Facies Association 2 is mainly characterized by wavy- to irregularly-laminated silty sandstones (Facies 5) and massive to wavy-laminated silt-rich mudstones (Facies 6) with minor amounts of high-angle cross-laminated sandstones (Facies 1), low-inclined cross-laminated sandstones (Facies 2) and horizontally-laminated sandstones (Facies 3). Facies Association 1 deposits dominate the southern part of the study area whereas Facies Association 2 sediments are more common towards to north. Stratigraphically, Facies Association 1 and 2 deposits occur intercalated with each other, and generally show two time Facies Association 2 sediments overlain by Facies Association 1 deposits. This intercalation of Facies Associations is best observed in the central part of the study area. In the south, Facies Association 1 deposits strongly dominate the succession, and in the north Facies Association 2 deposits are much more common, and do not show intercalation clearly. In the Lyons Formation, high-angle cross-laminated sandstones (Facies 1) are interpreted as remnants of fossil eolian dunes. Between these dunes, nearly flat to low-inclined dry interdunal areas occur and they are characterized by low-inclined cross-laminated sandstones (Facies 2) and horizontally-laminated sandstones (Facies 3). Chaotically-bedded to folded sandstones (Facies 4) represent internal deformation of dune deposits in the lower portion of dune flanks. Deposition of wavy- to irregularly-laminated sandstones (Facies 5) reflects wet to damp conditions in interdune areas. Massive to wavy-laminated silt-rich mudstones (Facies 6) indicate the presence of small ponds or lakes between dunes. Facies Association 1 deposits overall represent dry eolian conditions, and Facies Association 2 deposits represent wet eolian conditions. The distribution of Facies Association therefore indicates that dry and wet climates were generally alternating but overall dry climate conditions dominated the southern part of the study area whereas wet conditions were more prevalent in the north. Stratigraphically, the north to south transect reflects an expansion of dry conditions northwards despite the climate fluctuations, and a “Goldilocks” window of where to best observe climate cycles in the central part of the study area. This change in depositional conditions is exclusively observed along a north-south transect but not evident in an east-west direction. This study interprets the parts of the succession where Facies Association 1 sediments dominate as the paleo-erg center, and the portions where wet Facies Association 2 deposits are more prevalent as a paleo-erg margin environment. In the Lyons Formation, dry eolian deposits show good reservoir quality because of overall excellent sorting and roundness of the grains, while wet eolian deposits contains more fine-grained sediment which causes poorly sorting and reduction of porosity. Therefore, this study interprets that the main Lyons Formation plays are in the southern part of the study area within the paleo-erg center where dry eolian deposits are strongly dominating.Item Open Access Flowback quality characterization for horizontal wells in Wattenberg field(Colorado State University. Libraries, 2013) Jiang, Xi, author; Carlson, Kenneth H., advisor; Omur-Ozbek, Pinar, committee member; Bradley, Thomas H., committee memberThe development of hydraulic fracturing has driven both the need for more fresh water, and also has increased the amount of flowback being produced. Faced with a shortage of usable water, transportation issues, strict environmental regulation and environmental concerns, flowback management is an important topic for oil and gas companies. Recycle and reuse flowback waste is a promising method, since it can simultaneously reduce the need of more fresh water for fracking and decrease the potential environmental issues. Understanding the quality characteristics of flowback is significant for implementing the required treatment of flowback water. Flowback flows back to the surface during and after hydraulic fracturing and often flows for over a period of 3-4 weeks, though most wells finish in seven to 10 days. The fluid contains high total dissolved solids (TDS) and high salinity, and also contains some of the same chemicals that are pumped into wells. The volume of flowback can range from 10%-50% of initial injected fracturing fluid. In our study, sampling time was from March to April 2013 and all the samples were taken separately from Wells Ranch State PC USX #AA16-69-1HNL and Wells Ranch State USX #AA16-68-1HNL. The results in this report used well #68 and well #69. Well #68 was injected with PermStim fracture fluid (injected pH 5.0) and well #69 was injected with SliverStim fracture fluid (injected pH 10.2). Wellhead pressure, temperature, pH, dissolved carbon dioxide (CO2), bicarbonate (HCO3) and dissolved hydrogen sulfide (H2S) were tested in the field once samples were collected. TDS, chloride, sulfate, bicarbonate, aluminum, barium, boron, calcium, iron, magnesium, potassium, silicon, strontium and zirconium were tested by E-Analytics Laboratory. The objective of this paper is to analyze flowback water quality from two horizontal wells, located in the same place, which were injected with two different fracturing fluids. Based on the results of the temporal quality trend, this paper also intends to analyze the impact of different pH on water quality and the possible chemical reactions that occur during drilling and fracturing phases.Item Open Access Frac flowback water blending and treatment requirements based on spatial and temporal water quality analysis(Colorado State University. Libraries, 2015) Li, Wanze, author; Carlson, Kenneth H., advisor; Omur-Ozbek, Pinar, committee member; Stednick, John D., committee memberBecause of the large amount of wastewater generated with oil and gas production and the complex components of produced water, associates in the human health and environmental disciplines consider the treatment and reuse of produced water as a central issue for the petroleum industry. At present, produced water recycling is one of the best ways to reduce fresh water consumption in the hydraulic fracturing process and lessen environmental impact. This study focuses on the analysis of produced water quality and the optimization of the produced water recycling. Samples of produced water from more than two hundred horizontal wells in seven Integrated Development Plans in the Wattenberg Field were analyzed for temporal and spatial levels of total dissolved solids (TDS), sodium, chloride, calcium, and iron. Concentration of total dissolved solids, sodium, chloride and calcium were modeled to accommodate the different temporal functions in each Integrated Development Plan; the temporal logarithmic functions of each model allow prediction of produced water quality data for existing wells or new wells in certain regions. Iron concentration, however, closely correlates with geological formation, so the iron concentration of produced water must be determined spatially as an average value and maximum value in each Integrated Development Plan. A framework for optimizing produced water reuse is presented as part of this study. Typically, some volume of fracturing fluid is retained in wells; further, portions of flowback fluids might be injected into disposal wells. Produced water must be treated to meet recycled water quality requirements. In this study, coagulation/filtration, softening/clarification, and reverse osmosis (RO) were applied to treat samples effectively for suspended solids, total dissolved solids, sodium, chloride and calcium. Following treatment, the proper amount of fresh water needed to blend with the produced water must be determined. With sources of fresh water limited, the amount of water used to optimize the recycling of produced water is one of the most significant issues in the management of produced water. Calculating the quantity of fresh water necessary can be based on the quality of the fresh water, fracturing fluids and the targeted quality of the recycled water; in some cases, it might be based on the quantity of fracturing fluids and recycled water targeted. If the result based on quality is not less than the quantity based result, additional treatment will be required. Frac fluids modification could also be used in some conditions in this program, however, the cost of additives can be high, and additional treatment may be the better option. Most of recycle produced water quality with our treatment reaches requirements of fracturing fluids after blending with certain amount of fresh water. Produced water quality analysis of the horizontal wells in the Wattenberg Field and the established produced water recycling system program are supporting produced water management and the viability of produced water reuse. The Matlab produced water recycling program incorporates both internally sourced quality analysis data and external data uploaded from users. As a tool simulating produced water recycling, it can help users make good decisions to use in water management.Item Open Access Hazard mapping with direct reading instruments from facilities with high and low temporal variability(Colorado State University. Libraries, 2014) Lake, Kirk Allen, author; Koehler, Kirsten, advisor; Brazile, William, committee member; Omur-Ozbek, Pinar, committee memberThe purpose of this study was to develop novel sampling techniques employing relatively lower-cost direct-reading instruments (DRIs, instruments that report hazard intensity at near real-time resolution) for hazard mapping. Normally, personal sampling equipment worn by workers is used to determine personal exposure (time-weighted average) to a hazard for comparison with an occupational exposure limit (OEL). However, time-weighted average methods give the industrial hygienists (IH) no information on the spatial or temporal variability of the exposures. Hazard maps have been suggested as a way to represent spatial variability in hazard intensity displayed as contours of hazard intensity on the facility floor plan. Traditionally, expensive direct-reading instruments (e.g., sound level meters) are used to create these hazard maps by collecting numerous individual measurements over a single-traverse of a workspace. These instruments fail to determine the temporal variability in exposures through the workplace and as such, may miss important, but transient exposures. To overcome these limitations, we proposed that we could enhance both the spatial and temporal resolution, compared to single traverse sampling strategies, by deploying lower-cost static personal monitors that captured temporal variability distributed throughout the facility and roving personal monitors that capture spatial variability over multiple traverses throughout whole work shifts. These novel sampling techniques were evaluated at two locations with different temporal variabilities: a Plastic Manufacturing Facility (PMF), having low temporal variability, and the Engines and Energy Conversion Laboratory (EECL) at Colorado State University, having high temporal variability. The goals of the sampling at these locations were three-fold. First, we wished to determine if hazards maps generated with different sampling techniques were similar, depending on the temporal variability. Relative similarity was assessed by comparison of overall mean squared difference between maps and percent differences from location-specific interpolated values between hazard maps. Second, since the new sampling technique was not validated, we wanted to determine if measurements taken from personal noise dosimeters, operated as static or roving monitors, and a sound level meter (SLM) exceeded instrument accuracy, when collected at the same time and in close spatial proximity. Third, in the course of these studies, several occupational hazard assessments were also carried out at these locations. These assessments included determination of effective hearing protector usage, characterization of noise, vibration, and diesel exhaust hazards, and evaluation of noise and diesel exhaust engineering controls.Item Open Access Impact of inoculum source and primary carbon source on biotransformation of pharmaceuticals and personal care products(Colorado State University. Libraries, 2017) Kim, Sunah, author; De Long, Susan, advisor; Sharvelle, Sybil, committee member; Omur-Ozbek, Pinar, committee member; Prenni, Jessica, committee memberTo view the abstract, please see the full text of the document.Item Open Access Implementation of energy efficiency practices into U.S. retail sector by facilities managers(Colorado State University. Libraries, 2022) Saadatian Farivar, Armin, author; Olbina, Svetlana, advisor; Ozbek, Mehmet E., committee member; Omur-Ozbek, Pinar, committee member; Besiktepe, Deniz, committee memberReview of literature indicated that an in-depth analysis of implementation status of energy efficiency practices into U.S. retail sector, their benefits, barriers that prevented their wider implementation, and potential solutions for increasing the sector's energy efficiency was missing. The research purpose was to explore the status of implementing energy efficiency practices into the U.S. food and non-food retail sectors utilizing an in-depth review of the literature and a survey. To accomplish the research purpose, the following four research questions were examined: 1) To what extent do facilities managers in the U.S. integrate sustainable practices to achieve energy-efficient retail facilities? 2) What are the realized and perceived benefits of implementing sustainable practices by facilities managers to achieve energy-efficient retail facilities in the U.S.? 3) What are the realized and perceived barriers to implementing sustainable practices by facilities managers to achieve energy-efficient retail facilities in the U.S.? and 4) What do facilities managers propose as viable solutions that could help wider implementation of energy-efficient practices in the U.S. retail sector? Ninety-six facilities management professionals responded to the survey. The gathered data were analyzed utilizing descriptive statistical methods, and statistical tests such as pooled two sample t-tests and Welch-Satterthwaite t-tests. The research findings indicated that a majority of facilities managers that participated in the survey integrated energy efficiency practices into their retail facilities. Facilities managers perceived the integration of building systems such as energy efficient electrical lighting and energy efficient HVAC systems as effective practices in enhancing the energy efficiency of their facilities. Respondents that integrated energy efficiency practices perceived that reduced energy consumption and lower energy bills were beneficial. Similarly, respondents that never integrated energy efficiency practices perceived that integration of such practices could result in benefits such as reduced energy consumption and lower energy bills. However, respondents perceived no reduction of CO2 emissions. Respondents that integrated energy efficiency practices perceived that financial constraints prevented them from implementing such practices. Respondents that never integrated energy efficiency practices perceived that teamwork inefficiencies, lack of negotiation skills, and lack of support for energy efficiency practices from upper management prevented the use of energy efficiency practices in their facilities. Facilities managers proposed incorporation of commissioning into the building's life cycle, and proactive operation and maintenance of sustainable building systems as viable solutions that could help wider implementation of energy-efficient practices in the retail sector. The study is significant as the U.S. retail sector, among commercial buildings, accounts for the most energy consumption per year. Hence, identifying the most effective energy efficiency practices, their benefits, barriers that prevented wider implementation, and utilizing potential solutions proposed by facilities managers could enhance energy efficiency of this sector.Item Open Access Investigating potential groundwater outflows: Cottonwood sub-basin, Joshua Tree National Park, California, USA(Colorado State University. Libraries, 2019) Boyle, John, author; Sanford, William, advisor; Ronayne, Michael, committee member; Omur-Ozbek, Pinar, committee member; Harvey, Forrest, committee memberThis study utilizes Electrical Resistivity Tomography (ERT) to investigate potential groundwater outflows of the Cottonwood sub-basin (CsB) in Joshua Tree National Park (JOTR), California. Southern JOTR depends on one groundwater well (LUB-23) screened in an unconfined aquifer unlike the northern section which obtains its water from the municipal water system of the town of Joshua Tree. Depth to water was reported at 67m (219 ft) below ground surface (bgs) in 2017, a drop of almost 15m (49 ft) since installation in 1958. This variability in water level drives the need for a definitive water budget particularly since there is only one groundwater well. To contribute to developing a water budget, this study focused on investigating a potential groundwater connection between the CsB and the larger neighboring Pinto Basin. Interpretation of the subsurface resistivity models showed lack of a groundwater connection (or lack of contiguous low resistivity distribution) thus, this study concludes there is no groundwater connection or underflow at the boundary of the CsB and the Pinto Basin. Depth to water readings, which confirmed the water table was at 58m (190 ft) bgs. suggest the reported depth to water of 67m (219 ft) did not likely represent the static water level. Water quality and stable isotope analyses of groundwater samples were collected and compared to analyses performed from 2009 showing little variability over the 9-year period between sampling. Thus, no indications that pumping has modified chemistry or isotope composition.Item Open Access Investigation of storage-phosphor autoradiography for alpha emitters on different types of filters(Colorado State University. Libraries, 2019) Sorcic, Ashley, author; Sudowe, Ralf, advisor; Brandl, Alexander, committee member; Omur-Ozbek, Pinar, committee memberNumerous incidents in the past have resulted in the release of radioactive contamination into the environment, some of which require continuous monitoring decades later. Past and potential future incidents encourage governments and regulating agencies to develop procedures and methods to deal with nuclear emergencies, decontamination and decommissioning, and historical preservation in the face of a possibly dangerous environment. One technique which may assist in forensics and clean-up efforts is digital autoradiography. Digital autoradiography is based on the creation of luminescence due to the interaction of ionizing radiation with the storage phosphor. The resulting image can provide information about the amount and spatial distribution of the radioactivity in a sample. While the technique is typically used for the imaging of beta-emitting radionuclides, it can also be used for alpha emitters. Previous work has shown a correlation between the radioactivity of the sample and the intensity of the light emitted by the phosphor. In addition, it was observed that the luminosity varied for different alpha emitting isotopes. The current work extended this research to other alpha emitting isotopes and the effect of the energy of the emitted alpha particle on the response of the phosphor screens. In addition the effect of different types of air filters as source material was investigated, as well as the response of Multi-Sensitive storage phosphor screens compared to SuperResolution screens. The last major variable considered was how wrinkled the filters were; this variable was first considered shortly after the sample preparations were complete.Item Open Access Modeling of wastewater volume from unconventional oil and gas fields in Wattenberg field, and evaluation of low salinity waterflood enhanced oil recovery on shale wells(Colorado State University. Libraries, 2016) Bai, Bing, author; Carlson, Kenneth, advisor; Catton, Kimberly, committee member; Stright, Lisa, committee member; Omur-Ozbek, Pinar, committee memberReuse of wastewater from hydraulic fracturing (flowback and produced water) is a sustainable option for wastewater management practice in unconventional oil and gas fields. Reuse reduces fresh water demand but also lowers the environmental footprint by reducing the storage and transportation of both fresh and wastewater. A successful reuse practice requires a thorough understanding of both the quantity and quality of the wastewater, and more importantly, its potential impacts on well performance. In the first part of this study, wastewater production models were developed for horizontal shale wells in Wattenberg field .In addition, a solid characterization and distribution analysis on wells fractured with fresh and recycled water was performed to understand their impacts on wastewater quality. The second part of this study focuses on understanding the mechanisms of low salinity waterflood (LSF) in unconventional shale wells, and how oil recovery is impacted by the total dissolved solids (TDS) of the recycled brine. Results from the studies above are summarized in Chapter 4 through Chapter 7. A framework for water production prediction was developed in Chapter 4. Water production models were developed with Arps equation for horizontal wells from five fields in Wattenberg field. For a better data fitting and modeling, three time periods were defined: Frac flowback, transition period and produced water. The frac flowback period is the first one month after production starts, followed with 5 months of the transition period and, thereafter, produced water period. A correlation was found between water production volume and locations of wells,; thus, location is very important for estimating water production. Additionally, wells with low gas-oil-ratio (GOR) tend to have higher water recovery. In Chapter 5, sources of variability in flowback and produced water volumes from horizontal oil and gas wells were identified from external factors (time, location, type of frac fluids, wellbore length, and water source).. Horizontal wells in the Denver-Julesburg basin operated by Noble Energy were studied and results show that water production varies with time, location and wellbore length.. Additionally, production volume variation with fracturing fluid type and water source (fresh versus recycled) was explored. Results indicate that both of these variables should also be considered when developing a general model for water production. A guar-based frac fluid resulted in greater water production when compared to a cellulose derivative-based fluid. Finally, wells fractured with a fresh water based fluid had significantly greater produced water volume than geospatially-paired wells with a 1/7-recycled/fresh blend based fluid. Chapter 6 provides a qualitative and quantitative characterization of solids in frac flowback and produced water from five horizontal wells at two separate sites in the Wattenberg field of Northern Colorado. The difference in solids from wells fractured with fresh water and recycled water is compared, and their distribution and characterization are identified by particle size distribution measurement and X-ray photoelectron spectroscopy (XPS). Results show that particle were smaller and more uniform in produced water samples collected during the first week of production from the wells fractured with recycled water, suggesting that the recycled water was more compatible with the shale formation and wells fractured with recycled water tend to clean out faster. Chapter 7 investigates two of the fundamental mechanisms of LSF, clay swelling and diffused double layer (DDL) expansion. Both mechanisms are impacted by the salinity/total dissolved solids (TDS) concentration of the injection water. To test these mechanisms, clay swelling tests and real-time contact angle measurements were performed in this study. Spontaneous imbibition was also conducted, with Niobrara shale core plugs from Denver-Julesburg Basin, to compare oil recovery from low salinity and high salinity brine. Results show an increase in oil recovery when the TDS of brine falls between 400 and 10,000 mg/L. These results also indicate that LSF improves oil recovery from unconventional shale formation, and therefore, an optimal TDS concentration exists for highest oil recovery.Item Open Access Optimizing water management in hydraulic fracturing(Colorado State University. Libraries, 2016) Esmaeilirad, Nasim, author; Carlson, Kenneth, advisor; Omur-Ozbek, Pinar, committee member; Catton, Kimberly, committee member; Olsen, Daniel B., committee memberTo view the abstract, please see the full text of the document.Item Open Access Radiocesium soil to understory plant transfers in Fukushima forests(Colorado State University. Libraries, 2018) Workman, Daniel, author; Johnson, Thomas, advisor; Sudowe, Ralf, committee member; Omur-Ozbek, Pinar, committee memberThe objective of this research was to investigate the activity of radiocesium in plants and soil found in forested areas near the Fukushima Dai-Ichii Nuclear Power Station (FDNPS). Plant samples and 15-cm soil core samples were collected at four sampling locations. The quantity of soluble and exchangeable amounts of 137Cs in soil was measured by performance of two sequential extractions using de-ionized water and ammonium acetate respectively. The remaining radiocesium bound to the soil following the extractions was considered strongly bound to soil particles and whose movement into either soluble or exchangeable concentrations is slow. The distribution of the different forms of radiocesium were developed throughout each 15-cm soil core as measured using a High Purity Germanium Detector (HPGe). An analysis of correlation between plant activity versus plant root area and exchangeable radiocesium resulted in limited success. It remains probable that quantifying plant root radiocesium distribution can aid in predicting plant uptake, but it is believed that the concentrations of competing ions in soil should also be quantified and parameterized as well as additional possible routes of intake (throughfall). Concentration ratios (137Cs plant activity/137Cs soil activity) of 12 plants were calculated and exhibited a broad range from 0.01 to 2.5. The broad range of plant concentration falls within the International Atomic Energy Agency Parameter Handbook values of herbaceous plants in clay soils. Concentration ratios appear similar within sampling locations which suggests that additional soil characteristics (clay content, competing ions) can be used to describe plant uptake of radiocesium.