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Decadent Ekphrasis in The Picture of Dorian Gray
Get PDFOscar Wilde’s The Picture of Dorian Gray, as a novel about aesthetes and decadent artists, has several acts of ekphrasis, the process by which visual art is detailed using a verbal description. Unlike the traditional use of ekphrasis, Wilde tends to leap past the surface of the portraits in his novel and ponder the hidden depths of the painting’s subjects. This mode of ekphrasis contains a gap between the actual depiction in the portrait and the affective response of the viewer and has its roots in the work of Wilde’s mentor, Walter Pater. Pater believes that personality and emotional suggestiveness are what matter most in art, so his own ekphrases reflect these beliefs. This often requires a leap between what is seen on the surface to what is suspected in the depths in a manner similar to W.J.T. Mitchell’s description of ekphrasis as a project about overcoming difference. Though Wilde uses this form of ekphrasis, his novel shows by the deaths of Dorian Gray and Sybil Vane that there is something wrong or dangerous about it. This study looks at this type of ekphrasis in Wilde’s novel and how he critiques this mode
Study of multicomponent of hydrocarbon systems with molecular dynamics simulation
Get PDFMolecular Dynamics (MD) simulation is a powerful tool used in various research fields such as petroleum, geoscience, biochemistry, physics, and materials science. The unique merit of MD simulation is that it can investigate the complex structures or systems of interest at the atomic or molecular level, which could be inaccessible to experimental methods. A naturally accumulated hydrocarbon reservoir is a complex multi-component system where complex phase behavior occurs when different recovery techniques are applied. Given that hydrocarbons are stored in nanoscale to mesoscale pores, MD simulations have widely been used in petroleum engineering to study the interaction between pore-wall and fluids inside the pore body. For example, MD simulation has been widely used to observe the adsorption/desorption and diffusion of gas molecules in carbon nanotube/nanoslit for understanding the gas behaviors in the shale reservoir. Similarly, hydrocarbon products such as asphalts are complex mixtures that pose challenges in molecular-level studies but can be good candidates for MD simulation. In summary, MD has been used in this dissertation research to study the interfacial tension change for CO2 EOR and rejuvenating asphalt.
The first research project uses MD to study the options for rejuvenating aged asphalts with waste cooking oil (WCO) and waste polyethylene (WPE). The asphalt binder in pavement degrades over time due to oxidation and loss of volatile components resulting from weathering and utilization. Using waste to modify and recycle aged asphalt brings environmental and economic benefits. MD study of WCO for the aged asphalt shows that adding 10 wt% Triglyceride (TG, the main component of WCO) can decrease the viscosity (from 83 cP to 69 cP) and increase the self-diffusion coefficient (from 2.81×10^(-7)to 3.24×10^(-7) (cm^2)/s) of aged asphalt at its compaction conditions. The radial distribution function analysis revealed that the asphaltene-asphaltene nearest neighbor distance increased from 4.0 Å to 7.5 Å. The optimal dosage of TG was determined, which should be in the range of 10-15 wt% of aged asphalt. The results illustrate the fundamental mechanism of using the WCO to reclaim aged asphalt.
The WPE simulation shows that adding WPE could reduce the interactions between asphaltenes-resins, asphaltenes-aromatics, and asphaltenes-saturates. Low compatibility between asphalt and polyethylene results in phase separation of PE-modified asphalt. The maleic anhydride functional group (MAH) is chemically grafted on WPE (WPE-g-MAH) to enhance the compatibility and stability between PE and asphalt. The simulation results show that adding MAH functional group enhanced the interactions between asphaltenes-saturates and asphaltenes-aromatics, which was why MAH could enhance the compatibility between asphalt and WPE. Moreover, the simulation results demonstrated that both WPE and WPE-g-MAH couldn’t affect the interactions between asphaltenes-asphaltenes and mitigate the formation of asphaltene aggregations/clusters in aged asphalt, indicating PE and PE-g-MAH are not potential options to restore the rheological properties of aged asphalt.
The second project in this dissertation research uses MD simulation to study the interfacial tension between CO2-rich oil and the aqueous phase, which could fundamentally explain one of the synergetic driving mechanisms for CO2-related EOR. Recent laboratory tests showed promising results using urea as a CO2-generating agent for in-situ CO2 EOR. However, laboratory tests could not quantify the interfacial tension changes due to CO2 partitioning to the oil and aqueous phases. MD simulation is performed to study the interface and properties of the CO2/water/oil multi-components system in this research project. The simulation results demonstrate that the CO2 concentration of 40% is required to achieve a good reduction of the water/oil IFT for low-pressure conditions (<10 MPa) with 345 K, and that the water/oil IFT decreases significantly when the CO2 concentration is between 0 and 40%. While at higher CO2 concentrations of 40–80%, the IFT reduction is small. The literature has not reported this relationship between water/oil IFT and CO2 concentration. Our findings quantify the contribution of IFT reduction to oil recovery in CO2 EOR techniques. In addition, at low CO2 concentrations of 0~40%, CO2 molecules would change the orientation from the random distribution to parallel to the water/oil interface. Once the contact region of water/oil is saturated by CO2 molecules at around 40% concentration, increasing the CO2 concentrations does not change much of the IFT or CO2 orientation. This study illustrates the mechanism of IFT reduction from the molecular perspective that interfacial CO2 orientation is affected by bulk CO2 concentration and is closely correlated to the IFT change between oil and aqueous phases. The fundamental study of CO2 behavior at the water-oil interface is important to in-situ CO2 EOR and all CO2 flooding mechanisms. In addition, the procedures and analysis methods can be applied to other EOR projects for binary and multi-component systems studies for IFT analysis and property computation
Evaluation of the experimental warn-on-forecast system and WoF-hybrid 3DEnVar system on short-term forecasts for 2021 real-time cases
Get PDFOver the last few decades, it has become more important than ever to provide accurate forecasts for severe hazards that have become more common due to climate change effects. Over this time, several forecasting experiments have been performed with increasing computer power to better our understanding of these hazards. Currently, severe thunderstorms are diagnosed through a Warn-on-Detection paradigm, which bases severe warnings on storm reports or live radar data. To increase severe warning lead times, a Warn-on-Forecast has been developed, which focuses on the forecast evolution of ensemble systems to focus on probabilistic guidance of individual thunderstorm hazards. From this, the Warn-on-Forecast System (WoFS, defined in Section 1.3) and Warn-on-Forecast Hybrid System (WoF-Hybrid, defined in Section 1.5) have been developed.
The purpose of this study is to demonstrate and evaluate the capability of WoFS and WoF-Hybrid for predicting short-term severe weather forecasts that occurred during 2021 and help to identify room for future improvement. In addition to the 3 km grid-spacing, 18-member Experimental Warn-on-Forecast System (WoFS), which uses a Gridpoint Statistical Interpolation- Ensemble Kalman Filter (GSI-EnKF) data assimilation method, a 1.5 km grid-spacing, single member hybrid three-dimensional ensemble–variational data assimilation (3DEnVar System; referred to hereafter as WoF-Hybrid) has been tested for several years in NOAA Hazardous Weather Testbed (HWT) Spring Forecasting Experiments (SFE). Whether WoF-Hybrid exhibits attributes that complement WoFS is an open question. This is addressed by applying a spatial verification method, Fractions Skill Score (FSS), and object-based verification measures to 31 cases between April–December 2021. For the spatial verification method, WoF-Hybrid reflectivity FSSs are significantly lower than the WoFS member average at forecast initialization. Scores converge after one hour and are higher for WoF-Hybrid through the rest of the period. The difference in skill at initialization may be attributed to a higher reflectivity bias and a greater number of spurious convective cells in WoF-Hybrid.
The object-based method applied to reflectivity shows similar probability of detections (PODs) and false alarm ratios (FARs) for both systems. For updraft helicity (UH), however, WoF-Hybrid yields better PODs at all lead times. WoF-Hybrid better resolves UH swaths seen in plan-view analysis of forecast output, which tend to be narrow in the verification dataset. Partitioning cases based on event severity per the number of local storm reports, this study shows WoF-Hybrid has higher PODs and lower FARs than the WoFS member average for both reflectivity and UH in eight high-end events. WoF-Hybrid forecast reflectivity objects are both closer in size and location to observed objects than are WoFS objects.
Three severe weather events of 26 May and 27 May (multi-mode severe and heavy rain), and 10 December (rare winter tornado outbreak) are selected for detailed investigation. In each May case, PODs and FARs for both prediction systems were similar; however, for 10 December, WoF-Hybrid far outperformed WoFS in forecasts of the single most impactful thunderstorm in the dataset (quad-state tornadic supercell). These results suggest that using both WoF-Hybrid and WoFS forecast guidance may better support NWS forecasters' warning and forecast decisions
Global vs. Local: Panel Analyses of Environmental, Economic, and Political Gender Inequalities in Late Capitalism
Get PDFThis dissertation is an empirical attempt to bridge and synthesize two distinct sets of theories in the sociology of development and the study of cross-national inequalities. Through this study, I gather data on three types of inequality (i.e., environmental, economic, and gender/political) observed between and within nations of the world and create panel datasets that track countries’ profiles over time. By using a growth curve modeling (GCM) approach, I study the trajectories of inequality and explain them by time-invariant contextual (local) and time-varying external (global) factors. This dissertation aims to contribute to the development of a more general and comprehensive framework for studying the observed trends of inequality in the last three decades by implementing a methodology that effectively incorporates theoretical elements from multiple schools of thought. By discovering the underlying trajectories and contributing factors to nations’ inequality trends, this dissertation implies several policy suggestions in the conclusion section that can benefit the international, national, and local actors and policymakers concerned with the overall well-being of societies and people in both developing and developed countries
Modi’in and America: On the Power of Folklore & Place. The Saga of Garin Harmerkaz
Get PDFModiin is the site of both an ancient Jewish community and the modern nation’s ‘city of the future.’ This dichotomy is at the heart of a public battle between preservationists trying to raise awareness of the area’s rich Hannukah-related history and developers keen on making a profit. Less well-known is how this landscape has functioned as a mediating agent between American Jews and the State of Israel. The demilitarization of the Green Line made the civilian settlement of the long-time pilgrimage site feasible. For American olim looking to connect with their spiritual heritage, the notion of restoring Modiin offered an attractive alternative to Jerusalem’s volatility. Designated by the Jewish Agency as a destination for emigration from the American Reform community, this contemporary association builds on the region’s heritage as a bridge between the spiritual and physical realms of Israel.
In this paper, I ask how American Aliyah to Modi’in the years 1967-77 was organized, what the experience of immigration and settlement in the city was like for these emmigrants and the impact that they had on this city’s development. My work points to the significance of modern Modiin’s central planning and high quality of life. Additionally, my work contributes to the important historiographical literature on modern Israeli urbanization of such scholars as Maoz Azaryahu, Ilan Troen, Yehuda Grados and Esther Meir-Glitzenstein. I focus on a theme that appears repeatedly in archival documents: that these Americans were returning to the home of the Maccabees. I analyze the use of this theme to argue that it was central to lifting these immigrants’ expectations of the grandeur of their Aliya to Modi’in. This, in turn, significantly contributed to their disastrous experience of settlement and integration
Biotic and abiotic chemical weathering of siliciclastic sediments in cold environments
Get PDFDissertation Summary
Chemical weathering of silicate minerals is one of the most important Earth processes, moderating atmospheric carbon dioxide levels by consumption of carbon dioxide during hydrolysis of silicates (Nesbitt and Young, 1982; White and Peterson, 1990; Velbel, 1993; White and Blum, 1995; White et al., 1996; White and Brantley, 2003; White and Buss, 2014). Owing to its significance to the carbon cycle, and sensitivity to climatic conditions, chemical weathering and indices developed to determine the extent of weathering (i.e., Chemical Index of Alteration- CIA) have been the focus of significant studies aimed at investigating implications for paleoclimate in both terrestrial and extraterrestrial settings (i.e., Nesbitt and Young, 1982; Nesbitt and Young, 1989; Soreghan and Soreghan, 2007; Yang et al., 2016; Siebach et al., 2017; Deng et al., 2022). Chemical weathering leaves physical, chemical, and mineralogical signatures on rocks, sediments, and the aquatic environment, both via abiotic and biotic pathways. Therefore, weathering signatures studied on Earth are analogs for extraterrestrial signatures of surface alteration processes (i.e., Cannon et al., 2015; Olsson-Francis et al., 2017). However, abiotic and biotic weathering pathways in cold environments (i.e., within glacial settings) and subsequent weathering signatures remain poorly understood.
This dissertation investigates biotic and abiotic weathering signatures and pathways within various glaciated settings, with the focus on Antarctica and Iceland as climatic and mineralogical analogs of Mars. Non-glaciated settings are also investigated to compare weathering signatures generated within cold and hot climates. Chapters within this dissertation are formatted as peer-reviewed journal publications (in prep. or published).
The Chemical Index of Alteration (CIA) was developed to quantify the extent of weathering based on major oxides within silicates that are significantly associated with weathering: Al2O3, CaO, Na2O and K2O (Nesbitt and Young, 1982). CIA has been largely used to interpret paleoclimate, and correlated with climate parameters (mean annual temperature, MAT, and mean annual precipitation, MAP), especially with MAT within tropical soil profiles and watersheds on felsic bedrock (i.e., Nesbitt and Young, 1989, Rasmussen et al., 2011; Yang et al., 2016; Joo et al., 2018a). However, these correlations don’t seem to apply to glaciated settings (Deng et al., 2022), and various studies discuss shortcomings of applying CIA when mafic rock types are involved, as mafic major oxide components (such as FeO and MgO) are not incorporated within CIA calculations, and CIA is highly dependent on CaO that can result in artificially underestimated CIA values when the source rock contains high CaO (Nesbitt et al., 1996; Siebach et al., 2017; Mangold et al., 2019; Berger et al., 2020). Despite these documented issues, CIA remains widely utilized for various depositional settings, including potentially glaciated environments on Earth and Mars (i.e., Nesbitt and Young, 1982; Balburg and Dobrzinski 2011; Marra et al., 2017; Hurrowitz et al., 2017; Wang et al., 2020).
In Chapter 1, I investigate and compare weathering signatures (mineralogy, chemistry, grain size, and surface area) within mud-sized (<63 µm) sediments from both cold glaciated and hot non-glacial settings on felsic-intermediate bedrock to assess paleoclimatic implications of chemical weathering, attempting to decouple inherited provenance signatures from climatic signals. Use of ternary plots that are commonly used for chemical weathering and paleoclimate studies, such as A-CK-N, A-CKN-FM (Nesbitt and Young, 1982) and MFW (Ohta and Arai, 2007), illustrate that the effects of provenance and mafic mineral sorting (towards finer grain sizes) overshadow weathering trends (Nesbitt et al., 1996; von Eynatten et al., 2012; Mangold et al., 2019), except for tropical soils and fluvial muds from Puerto Rico. In addition, data from very different climatic settings have overlapping CIA values (indicative of weak to intermediate weathering) that also clustered together on A-CK-N diagrams, suggesting that assessing climatic trends using this method may lead to erroneous interpretations. In an attempt to remove the provenance signature from the data, we normalized sediment CIA values to the CIA values determined for their bedrock sources and tested the correlation with MAT and MAP. Though R2 values obtained from this multi-provenance and climate data set were enhanced, and showed better correlation of CIA with MAP, removing the tropical watershed from the data set eliminated any expected correlations. Overall, Chapter 1 shows that: 1) CIA and ternary plots for weathering are most useful when applied to tropical settings with uniform bedrock composition, where elemental weathering trends can be directly traced from the bedrock to first-cycle material (soil profiles/paleosols); 2) CIA values of muds from glacial settings overlap with values observed in hot and humid climates; and 3) no correlations were observed between climatic parameters (mean annual precipitation and temperature) and CIA in non-tropical fluvial sediments, suggesting that CIA is not a useful metric for modeling paleoclimate in glaciated settings.
Microbial organisms catalyze chemical weathering owing to their metabolic biproducts (organic acids, carbon dioxide, extracellular polymeric substances) which locally decrease the pH, and metabolic activity (i.e., photosynthesis) that significantly increases the pH of the overall weathering solution (Welch and Ullman, 1999; Montross et al., 2013; Olsson-Francis et al., 2012; Olson-Francis et al., 2017). Solute fluxes observed in the Antarctic McMurdo Dry Valleys (Gooseff et al., 2002; Marra et al., 2017; Stumpf et al., 2012) exceed expected abiotic weathering fluxes, which previous studies have attributed to microbial weathering (i.e., Lyons et al, 2015), as well as abiotic factors such as production of fresh high surface area silicates via glacial grinding priming them for chemical weathering (Anderson et al., 1997, Anderson, 2005; Stumpf et al., 2012; Marra et al., 2017). However, the effects of psychrophilic microbes in chemical weathering processes in Antarctica (as well as other glaciated settings) are not well known. Permafrost soil surface temperatures can reach 12°C due to radiative austral summer heating (Balks et al., 2002; Dolgikh et al., 2015), providing optimum growth conditions for cold-tolerant cyanobacterial mats (e.g., Kleinteich et al., 2012) that are widespread in meltwater stream banks and cryptoendolithic habitats of the topsoil (Cary et al., 2010; Cowan et al., 2010).
In Chapter 2, I investigate the role of the Antarctic benthic mat-forming (non-axenic) cyanobacterium, Leptolyngbya glacialis, on chemical weathering of (felsic-intermediate, Antarctic and basaltic, Iceland) glacial sediments at 12oC, representing permafrost surface temperatures, testing the hypothesis that microbial life increases weathering rates and solute fluxes within glacial settings. Results show silicate weathering rates in felsic sediments are three times faster with microbes than without, whereas biotic and abiotic weathering rates observed in mafic sediments are comparable, likely due to faster chemical weathering rates in basaltic sediments which directly provide nutrients to the microbes, reducing the need for direct microbial-facilitated weathering (scavenging). Results also show that microbes increase the solution pH and lead to up to four times higher bicarbonate concentration, suggesting they may play a key role in carbonate deposition in both felsic and mafic settings. Production of Fe-(hydr)oxide nano minerals and neo-formed clays may be potential inorganic biosignatures as they are closely associated with microbial biofilms, and similar phases were not observed in abiotic reactors. Note that this chapter has been published in Permafrost and Periglacial Processes (Demirel-Floyd et al., 2022), partially fulfilling doctoral degree requirements for the OU School of Geosciences.
Cyanobacteria have also played important roles within Earth history such as atmospheric oxygenation and the evolution of multicellular life (Lyons et al., 2014), while also surviving across multiple climatic extremes such as the Neoproterozoic “Snowball Earth” episodes (Hoffman et al., 1998; Fairchild and Kennedy, 2007; Ye at al., 2015; Brocks et al., 2017; Shizuya et al., 2021). These resilient organisms also are known to endure multiple environmental extremes (UV radiation, desiccation, salt, cold, etc.) within Antarctic glacial habitats (Gilichinsky et al., 2007; Cary et al., 2010; Cowan et al., 2010, Anesio and Laybourn-Parry, 2012), where they lead the primary production and play a fundamental role in Antarctic biogeochemical cycles (McKnight et al., 2004; Smith et al., 2017). Antarctic cyanobacterial mats also increase weathering rates, and therefore impact nutrient fluxes at warmer surface soil temperatures (12oC), as described in Chapter 2 (Demirel-Floyd et al., 2022). Though they are widespread in cold meltwater streams (McKnight et al., 1999, 2004; Van Horn et al., 2016), the role of cyanobacterial mats in cold temperature weathering is not well known.
In Chapter 3, I investigate biotic and abiotic silicate weathering rates and nutrient release at different temperatures (4°C and 12°C) and nutrient conditions (10 and 1000 times diluted), using the same felsic-mixed sourced Antarctic glaciofluvial sediments and basaltic-sourced Icelandic glacio-volcanic outwash sediments used in Chapter 2, testing the hypothesis that polyextremophilic cyanobacterial weathering rates increase under colder and nutrient-stressed conditions via enhanced production of extracellular polymeric substance (EPS) resulting in release of organic acids. Results show limited evidence of biological weathering of silicate minerals at cold temperature, yet microbe-mineral interactions still affect nutrient concentrations, particularly for Ca, Mg, Mn, P and N. However, increased nutrient and salt concentrations also increased the rate of solute release from the silicate sediments, even under abiotic conditions. These results indicate that concentration and chemistry of weathering solutes (salts) are important factors controlling weathering rates and nutrient fluxes in cold settings. This chapter will soon be submitted to Geomicrobiology Journal for initial peer review
Investigation of flexural behavior of reinforced concrete with 3D printed glass fiber reinforced polymer
Get PDFMore than 40 years of Fiber Reinforced Polymers in Civil Engineering has shown the widespread use and advantages of these unique composites. FRP composites are high strength, lightweight, corrosion resistant materials that are known for their long-term durability and performance in infrastructure applications. FRP composites are available in the form of sheets, rods, grids and winding strands that are used for a wide range of civil engineering applications. In the last decade, 3D printing technology for manufacturing FRP composites for construction applications has gained increased attention. With 3D printing technology, FRP composites can be printed with radical shapes and properties resulting in varied mechanical performances. Precise angles, optimized designs and radical shapes are also some of the several advantages that 3D printed FRP composites can offer. With increasing demand for 3D printed composites and with interest in using these composites for construction applications, it is very important to understand the behavior of these composites in concrete when used as reinforcement. Concrete - FRP bond behavior plays a significant role in controlling debonding failures in FRP-strengthened flexural elements ultimately contributing to their structural performance. In addition, compared to conventional Portland cement-based concrete, polymers in concrete can have a much different behavior due to better engagement with increased bond strength with the constituents. Polymers have known to have higher bond strength with other materials compared to cement due to lack of saturation in the latter. Therefore, the behavior of FRP, especially 3D printed FRP may be different in these different concretes. This work investigates the flexural behavior, failure modes and ductility of conventional FRP composites, conventionally manufactured and 3D printed, used as a reinforcement in concrete. Two types of concrete are investigated for understanding the flexural response of FRP composites. A Methyl Methacrylate based polymer concrete and Portland cement-based concrete reinforced with Glass FRP reinforcement. The results of this work show that both conventional and 3D printed FRP composites used as reinforcements in Portland cement concrete and Polymer concrete improve the moment capacity and flexural capacity of the beams. However, on average, 3D printed GFRP in Polymer concrete has improved flexural response than the 3D printed GFRP in Portland cement concrete. Microscopic analysis was conducted to observe damage in all the beams subjected to flexural testing. These investigations indicated that polymer concrete shows better engagement with the reinforcement.
The outcomes of this work show that 3D printed FRP composites are suitable for use in construction applications. Further understanding of the behaviors of 3D printed FRP composites in concrete lead a way to advanced concrete based reinforced composites that can be 3D printed in radical shapes and designed for tailored mechanical properties and performance for construction applications
Spin-mixing and Interferometry in Microwave-dressed Sodium Spinor Bose-Einstein Condensates
Get PDFThis thesis presents my research on spin-mixing and interferometry in an all-optically generated spinor Bose-Einstein condensate (BEC) of sodium atoms. The sodium atoms are loaded from a magneto-optical trap into a crossed optical dipole trap and are subsequently evaporatively cooled down to quantum degeneracy by ramping down the laser power. With our setup, we obtained nearly pure sodium BECs with atoms number of approximately 20,000 to 40,000.
We study the spin-mixing dynamics in the sodium spinor system. I present experiments on a resonant coupling between spin and spatial degrees of freedom beyond the single-mode approximation (SMA) during non-equilibrium dynamics in our sodium spin-1 BEC. These quench-induced spin oscillation experiments rely on microwave dressing of the hyperfine states, where F denotes the total angular momentum of the Na atoms. Our data show a slow baseline drift of the coherent spin population oscillation between and pairs when the effective quadratic Zeeman shift is tuned via microwave dressing to certain values. The baseline drifting indicates spin dynamics beyond the SMA. Our data agree well with the recent theory based on a -dependent, resonant coupling between spin and spatial degrees of freedom. We further explore these effects by scanning around the point of maximum baseline drift to map out this new resonance phenomenon as a function of .
I also present the result of our spin-mixing atom interferometer experiments. We experimentally demonstrate two new types of interferometry based on different initial states: single-sided seeding and double-sided seeding interferometers. The entangled probe states of the interferometers are generated via spin-exchange collisions in spinor BECs, where two atoms with the magnetic quantum number collide and change into a pair with . Our results show that our spin-mixing interferometers beat the standard quantum limit with a metrological gain of 3.96 dB in the single-sided atom interferometer with spin-mixing time t = 10 ms and 4.77 dB in the double-sided atom interferometer with spin-mixing time t = 8 ms. Our research on spin-mixing interferometry is useful for future quantum technologies such as quantum-enhanced microwave sensors and quantum parametric amplifiers based on spin-mixing. Our work paves the way for future light-pulse atom interferometry experiments, which involve the coupling between the spin and momentum degrees of freedom, and are useful for quantum-enhanced inertial sensing and gravimetry with BECs
Experimental Investigation of Synthetic and Microbial Surfactants for Enhanced Oil Recovery in Bone Spring Sandstones
Get PDFSurfactants have been used to increase hydrocarbon recovery to meet the increasing demand for oil and gas. This mechanism of using surfactants reduces the Interfacial Tension (IFT) at the fluid/fluid interface and wettability at the rock/fluid interface to mobilize trapped oil out of the pores. However, there are two main limitations of the surfactant flooding process—first, high reservoir temperature & salinity, and second, adsorption of surfactants on the rock surface. Surfactant adsorption alters wettability of reservoir rock from oil-wet to water-wet. However, excess adsorption may decrease oil recovery, especially in conventional reservoirs with high temperature and Total Dissolved Solids (TDS). This study tested two synthetic amphoteric surfactants, one nonionic biosurfactant, and a base case with produced brine to understand wettability, IFT, surfactant adsorption, and its effect on oil recovery in Bone Spring sandstone formation. Produced brine has a high TDS of 237,705 ppm, and test conditions were kept at 145oF and 500 psi pressure. First, surfactant stability tests and CMC measurements were performed on three surfactants. Then, IFT measurements were performed between crude oil and surfactant solutions along with produced brine. Next, wettability alteration was studied by measuring contact angle on oil saturated rock samples before and after being exposed with surfactants and produced brine. Then, surfactant adsorption experiments were performed using UV-Vis spectrophotometer to calculate the amount of surfactant getting adsorbed on the rock samples. Lastly, surfactants and brine imbibition experiments were performed on plug samples, and oil recovery was quantified using 12MHz Nuclear Magnetic Resonance (NMR) spectrometer. All the recovery experiments were repeated on the same three plug samples with approximately 30 wt.% clay. This study shows that all three surfactants reduced IFT and altered wettability, but biosurfactant showed low IFT, much lower surfactant adsorption, and made the sample most water wet as compared to amphoteric surfactants. Imbibition experiments showed that biosurfactant have the highest oil recovery, while amphoteric surfactants have oil recovery even lower than produced brine. This study shows that surfactant adsorption affects oil recovery, which leads to loss of surfactants from solution to the rock surface. Measurements also show that the adsorption of amphoteric surfactants increases with increased clay concentration which shows the efficacy of surfactants depends on rock mineral composition. This study suggests that biosurfactants with glycolipids can be used in shaly sandstones at high TDS and temperature. With oil recovery using biosurfactants being very close to produced brine, it might be more economical to use only produced brine with no surfactants
Wildfire risk along the wildland-urban interface in Oklahoma in relation to encroaching eastern redcedar
Get PDFAcross the United States, the number of wildfires has been increasing, but this can especially be felt in the Great Plains, where some of the most drastic increases in wildfire frequency and size have occurred. While frequent fires should seem somewhat normal in a grassland biome like Oklahoma, after European settlement, fire suppression has allowed woody vegetation, like Eastern Redcedar, to encroach onto the grasslands and dominate native vegetation. This leads to state transitions of a grassland biome to a woodier ecosystem, which can cause more intense wildfires. The metropolitan areas outside of Oklahoma City and Tulsa have the highest housing and population densities at risk and largest magnitude of wildland-urban interface. But some rural areas like Hinton and Woodward to Watonga show a high risk to wildfire in proportion to their low populations. Landowners need to properly manage these areas to prevent fires rather than suppressing them