Master of Science (MS), Ohio University, 2019, Chemical Engineering (Engineering and Technology)

Low porosity and permeability of Marcellus and Utica shale often limit the hydrocarbon recovery. To increase shale porosity, hydrothermal deformation (HTD) of Marcellus shale was performed and the effects of subcritical water temperature and reaction time on porosity were evaluated. HTD experiments were performed at the water saturation pressure (225.3, 576.8, and 1245.5 psi) for corresponding water temperature at 200, 250 and 300 °C for one, three and six hours of residence time. Low-temperature N2 adsorption was used for the porosity measurement of raw and treated shales. Furthermore, the morphology of raw and HTD shale samples was analyzed with scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and X-ray diffraction analyzer (XRD). It was observed that shale porosity was significantly enhanced by HTD conditions. For instance, HTD at 300 °C (1245.5 psi) for six hours of residence time, shale porosity increased more than four times compared to raw shale. This porosity was attributed to leaching of calcite, clay, and quartz, which was confirmed by analyzing HTD process liquids by Induced Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Shale permeability depends on the width of fracture aperture. HTD experiments of Utica shale core plugs were performed and the changes in the fracture aperture widths were observed with respect to HTD reaction conditions. Digital microscope was used to measure the fracture aperture width and it was observed that fracture aperture width was increased with the increase in HTD temperature and pressure. For example, HTD at 300 °C (1245.5 psi) for three hours residence time, fracture aperture width increased more than seven times compared to raw shales. Micro-fracture permeability for the raw and HTD shales was also estimated by using conceptual matchsticks model. Micro-fracture permeability was also increased with the increase in HTD temperature. Micro computed tomography (micro-CT)-scan was used to observe t (open full item for complete abstract)

Committee: M. Toufiq Reza PhD (Advisor); Marc Singer PhD (Committee Member); John Staser PhD (Committee Member); Martin Kordesch PhD (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy (PhD), Ohio University, 2015, Chemical Engineering (Engineering and Technology)

The primary objective of this work is to investigate the corrosion behavior of carbon steel in simulated CO2-EOR environments when O2 is present in the CO2 supply. A preliminary study was first conducted at low pressure to investigate the effect of O2 on the protectiveness of iron carbonate (FeCO3) corrosion product layers in mild steel CO2 corrosion. Carbon steel (UNS G10180) samples were immersed in a CO2 saturated 1 wt.% NaCl electrolyte for 2 days to facilitate formation of a protective FeCO3 layer on the steel surface. Temperature and pH were maintained at 80°C and 6.6, then 1 ppm O2 was introduced to the electrolyte. The impact of the oxidant(s) was studied after samples were exposed for one week to test conditions. Electrochemical measurements indicated increased corrosion rates over the first two days of O2 exposure, with a decrease in corrosion rate thereafter due to corrosion product formation that conferred some degree of protection to the steel surface. When O2 was introduced after carbonate formation, the corrosion rate did not increase. Although the final corrosion rates of all tests were relatively low (less than 0.2 mm/y), localized corrosion was observed. Surface analysis showed attack of iron carbonate crystals and formation of iron (III) oxides. This degradation of initially formed FeCO3 occurred concurrently with the development of localized corrosion features as deep as 80 µm. High pressure experiments were then conducted at CO2-EOR simulated downhole conditions. The effect of O2 (4 vol. %) on the corrosion performance of mild steel (UNS G10180) in CO2-saturated brine was investigated using a 4-liter autoclave at two different temperatures (25 and 80°C) and pressures (40 and 90 bar). Experiments at 25°C are categorized as `FeCO3-free' while experiments at 80°C are termed `FeCO3-forming'. The work included electrochemical measurements, weight loss determination, and characterization of the corrosion products. Severe corrosion was observed on (open full item for complete abstract)

Committee: Srdjan Nesic (Advisor); Yoon-Seok Choi (Committee Member); John Staser (Committee Member); Michael Jensen (Committee Member); Dina Lopez (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2010, Chemical Engineering

Supercritical (high pressure) CO2, owing to its ability to make polymers pliable at temperatures much lower than the glass transition temperature (Tg), has been established as a very promising solvent for numerous macro scale polymer processing applications. In this work, we have tried to expand the scope of supercritical CO2 assisted polymer processing to nano length scales with particular focus on manufacturing biomedical devices from polymer thin films. At such small length scales, however, the properties of the polymer become size dependent since the interfacial effects start dominating the bulk effects. As a result, adapting the macro and micro level fabrication technologies to nano level is not straightforward and requires integration of both theoretical and experimental tools. We have used CO2 assisted Nano-Imprint Lithography (CO2-NIL) for fabricating nanochannels on polystyrene thin films. CO2-NIL is a novel technique in which the features from a rigid mold are transferred on to a CO2 pressurized polymer thin film by application of compressive force. We have explored efficiency of pattern transfer, resolution, and effects of molecular weight on transferability of patterns, and have thus established CO2-NIL as a highly efficient and cost effective fabrication technique capable of transferring patterns as small as 20 nm in step height. To understand the surface characteristics and the molecular level effects of CO2 on polymer thin films, which are essential for optimizing the nanoscale experiments, we have used Polymer Density Functional Theory (PDFT) as our primary tool since it provides an adequate balance between the amount of details extracted and the computational costs involved. PDFT is a statistical mechanics based approach in which we express the free energy of the system as a functional of spatially varying density distributions of CO2 and polymer segments. Equilibrium density distributions, free energy at equilibrium, and hence the equilibrium pr (open full item for complete abstract)

Committee: Isamu Kusaka PhD (Advisor); David L. Tomasko PhD (Committee Member); L. James Lee PhD (Committee Member); Susan Olesik PhD (Committee Member) Subjects: Chemical Engineering