Miscible gas injection processes could be among the most widely used enhanced oil recovery processes. Successful design and implementation of a miscible gas injection project depends upon the accurate determination of the minimum miscibility pressure (MMP) and other factors such as reservoir and fluid characterization. The MMP indicates the lowest pressure at which the displacement process becomes multicontact miscible. The experimental methods available for determining MMP are both costly and time consuming. Therefore, the use of correlations that prove to be reliable for a wide range of fluid types would likely be considered acceptable for preliminary screening studies. This work includes a comparative and critical evaluation of MMP correlations and thermodynamic models using an equation of state by PVTsim software. Application of gas injection usually entails substantial risk because of the technological sophistication and financial requirements to initiate the project. More detailed, comprehensive reservoir engineering and project monitoring are necessary for typical miscible flood projects than for other recovery methods. This project evaluated effects of important factors such as injection pressure, vertical-to-horizontal permeability ratio, well completion, relative permeability, and permeability stratification on the recovery efficiency from the reservoir for both miscible and immiscible displacements. A three-dimensional, three-phase, Peng-Robinson equation of state (PR-EOS) compositional simulator based on the implicit-pressure explicit-saturation (IMPES) technique was used to determine the sensitivity of miscible or immiscible oil recovery to suitable ranges of these reservoir parameters. Most of the MMP correlations evaluated in this study have proven not to consider the effect of fluid composition properly. In most cases, EOS-based models are more conservative in predicting MMP values. If screening methods identify a reservoir as a candidate for a miscible injection project, experimental MMP measurements should be conducted for specific gas-injection purposes. Simulation results indicated that injection pressure was a key parameter that influences oil recovery to a high degree. MMP appears to be the optimum injection pressure since the incremental oil recovery at pressures above the MMP is negligible and at pressures below the MMP recovery is substantially lower. Stratification, injection-well completion pattern, and vertical-to-horizontal permeability ratios could also affect the recovery efficiency of the reservoir in a variety of ways discussed in this work.

No description available.

Polystyrene (PS) carrying a terminal nitroxide group was synthesised by anionic polymerisation. The ESR spectra of the PS in bulk and in blends with polyisoprene (PIP) recorded over a range of temperatures indicate that the motional freedom of a proportion of the labelled PS chain ends is enhanced by the presence of PIP especially at elevated temperatures (above ca. 400K). The possibility that this effect is due to a trend towards macroscopic miscibility between the two homopolymers at temperatures in the region of 400K is ruled out by a range of experiments including differential scanning calorimetry and interfacial tension measurements. It is concluded that in PS/PIP blends there is a greater than average concentration of PS chain ends in the PIP-enriched environment of the phase boundaries. This work provides the first experimental verification of the prediction, based on thermodynamic considerations, that in immiscible blends of polymers chain ends are located in preference to internal segments at the interfacial region (interphase).

Cette étude porte sur la production et la caractérisation de fils élastomères à base de polypropylène (PP) et d’élastomères thermoplastiques (TPE). L’étude du filage par voie fondue des polymères sous forme de mélanges montre une relation entre les propriétés des fibres et la morphologie du mélange. Les propriétés élastiques ne sont améliorées qu’avec le changement de morphologie, et le passage à une matrice TPE majoritaire. Les mélanges filés avec un taux de TPE élevé (80 et 90%m) montrent un changement de structure cristalline du TPE, qui augmente la récupération élastique. L’étude du filage sous forme de structure bicomposante cœur/gaine (C/G), où le TPE est introduit dans le cœur de la fibre et le PP en gaine, montre l’influence du rapport massique C/G sur les propriétés mécaniques des multifilaments. Les propriétés élastiques ne sont pas améliorées pour les différents rapports massiques C/G étudiés, en raison du comportement plastique de la gaine. Le meilleur compromis en termes de propriétés et de mise en œuvre est obtenu avec une structure hybride. Le multifilament mis en œuvre est un fil bicomposant C/G, mais avec un mélange TPE/PP en gaine et le TPE vierge en cœur. Les résultats montrent toujours une diminution des propriétés mécaniques avec l’augmentation du rapport massique C/G, mais une amélioration de la récupération élastique est observée. Pour des taux de TPE équivalents, les propriétés de la structure hybride sont supérieures à celles déterminées pour les mélanges sous forme de fibres monocomposantes. Pour finir des essais de texturation et de tissage démontrent une possible utilisation de ces multifilaments dans des procédés de transformation textile. / The aim of this work is the study of elastomeric fibers processed by melt spinning of polypropylene (PP) and thermoplastic elastomers (TPE). Multifilaments produced by a melt spinning process of polymers blend show a relationship between fiber properties and their morphology. Elastic properties are enhanced only when the majority phase is TPE. Yarns melt spun from blends with high TPE rates (80 and 90 wt.%) show a transition of the crystal structure from pseudo hexagonal to orthorhombic with the increase of drawing ratio applied which improve elastic recovery. Melt spinning of core/sheath (C/S) bicomponent fibers is performed using TPE as the core and PP as the sheath. The study reveals a decrease in mechanical properties with increasing the C/S ratio, and elastic properties are not modified for the different C/S ratios studied. This behavior can be explained by the plastic deformation of the polypropylene sheath. In order to improve processability and properties, melt spinning of core-sheath bicomponent fibers with different C/S ratios is performed using EOC and polypropylene blends as the sheath and pure EOC as the core. The results still show a decrease in mechanical properties with the increase in the C/S ratio, but elastic properties are enhanced. For the same TPE content, elastic recovery and mechanical properties are higher for hybrid fiber than for blend melt spun as monocomponent fibers. Finally texturing and weaving tests prove a possible use of the multifilaments in textile processes.

Immiscible liquids, including chlorinated solvents, have proven to be a lasting source of subsurface contamination at many hazardous waste sites. Continued improvement of site characterization and determination of applicable remediation technologies can be achieved by further understanding of the transport and fate of these contaminants. The transport and fate of trichloroethene (TCE) was investigated through miscible displacement and dissolution experiments. Miscible displacement experiments were conducted using homogeneously packed columns with several porous media encompassing a range of particle size distributions. Immiscible liquid dissolution was investigated using homogeneously packed columns containing a residual saturation of trichloroethene. The same porous media were used for immiscible liquid dissolution experiments. Mathematical modeling of miscible displacement and dissolution experiments was conducted using a one-dimensional single region or multi-region model. Imaging of immiscible liquid dissolution was also conducted, using Synchrotron X-ray Microtomography imaging at Argonne National Laboratory, Argonne, IL. Dissolution experiments exhibited nonideal dissolution behavior that was apparent in observed effluent data and in collected imaging data. Nonideal behavior was manifested as secondary regions of relatively constant aqueous concentrations occurring for a number of pore volumes. This behavior was observed to increase in magnitude as particle size distribution of the porous media increased. During imaging, immiscible liquid blobs were observed to dissolve throughout the column during dissolution. This behavior is also indicative of nonideal dissolution, as it would be expected that dissolution would first occur for the blobs nearest the inlet and then proceed upward through the column as dissolution progressed. In many cases, a multi-region modeling approach was necessary to successfully represent the nonideal behavior observed. Comparisons were made between the natural porous media used for this research and a well-sorted sand. Nonideal dissolution was not observed in the well-sorted sand.

Alloy castings are usually solidified with a coarse columnar grain structure under normal casting conditions unless the mode of the solidification is carefully controlled. It is desirable for the grain structure to be fine and equiaxed to improve their mechanical performance as finished castings. It is possible to develop a fine and equiaxed grain structure either by increasing the number of nucleation sites or by grain multiplication. Immiscible alloys with a microstructure in which a soft phase is dispersed homogeneously in a hard matrix have significant potential applications in advanced bearing systems, especially for the automotive industry. Despite considerable efforts made worldwide, including extensive space experiments, no casting techniques so far can produce the desired immiscible microstructure of alloys. Experimental results on Al-Sn-Cu immiscible alloys have confirmed that intensive shearing using melt conditioning by an advanced shearing technology (MCAST) unit, is an effective way to achieve a fine and uniform dispersion of the soft phase without macro-demixing, and that such a dispersed microstructure can be further refined in alloys with precipitation of the primary Al phase prior to the demixing reaction. In addition, it was found that melt shearing at 200 rpm for 60 s will be adequate to produce a fine and uniform dispersion of the Sn phase, and that a higher shearing speed and prolonged shearing time can only achieve further minor refinement. A study of Al-Si hypoeutectic and hypereutectic alloys presents the effects of the processing temperature and intensive shearing on the microstructural and mechanical properties which have been investigated systematically. Attempts have been made to explain the solidification mechanism with intensive melt shearing. The sheared melt was cast into tensile test samples by high pressure die caster (HPDC) to examine the microstructures and mechanical properties. The experimental results reveal that significant grain refinement and uniformity of grains was achieved by the intensive shearing and also a considerable increase in mechanical properties with pouring temperature by changing intermetallic particles morphology, the position of defect band and reduced microscopic defects.

Free machining alloys containing soft immiscible phases in the aluminium (Al) matrix, like lead (Pb) and bismuth (Bi), are of great industrial interest. Typical applications in automotive industry are components requiring very high machinability, such as braking pistons and antiblocking system (ABS) housings. Presence of soft immiscible phases is giving their machining properties to this class of alloys. These phases melt due to localised heat build-up generated by machining process and induce chips breaking. Such type of alloys offers best in class performance when the soft phase is uniformly distributed in the Al matrix. The main objective of this work was to develop a method to tailor the distribution of the immiscible phase particles in the final solidified structure of DC cast billets in order to provide enhanced machinability while keeping low levels of Pb and/or Bi additions. As a consequence, another objective of this study was to improve recyclability of such alloys as well as to reduce their environmental impact. Three categories of Al-Pb alloys and different solidification paths were studied: hypermonotectic Al-3Pb, monotectic Al-1.2Pb and industrial hypo-monotectic free machining alloy containing both Pb and Bi. A newly developed melt conditioning combines mechanical, thermal and chemical treatments to obtain a very fine and uniform distribution of the immiscible phase droplets and eliminate compositional heterogeneities. The effect of these new melt treatments on microstructure was evaluated. For the soft phase droplets size was reduced and distribution becomes finer and more homogeneous under the individual effect of each of the treatments and optimum results obtained with the combination of them. These new melt treatments affect not only the nucleation of the Pb/Bi droplets, enhancing their heterogeneous nucleation but reduces considerably the Marangoni motion and Stokes sedimentation reducing therefore the droplet coalescence and restricting their growth. As a consequence of this improved microstructure, mechanical properties and machining performance were enhanced considerably. The results from this study provide a promising new microstructure with a fine and uniform distribution of droplets.

Master of Science / Department of Geology / Matthew Brueseke / It is generally accepted that beneath flood basalt provinces, Cu-Ni-PGE sulfide deposits may be found (Ridley, 2013). The focus of this study is the Steens Basalt, a mid-Miocene flood basalt from the northern Great Basin (USA) which contains between ~5-400 ppm copper and is characterized by large plagioclase phenocrysts, some of which can contain primary inclusions of copper despite the chalcophile nature of Cu (Hofmeister and Rossman, 1985; Johnston et al., 1991). The purpose of this project is to identify the distribution of Cu among coexisting phases in Steens Basalt, test whether plagioclase crystals in Steens lavas can host Cu, even when Cu is not visible, and test whether sulfide minerals/droplets are present in Steens Basalt samples with low Cu concentrations. Samples of Steens lavas were examined for sulfide minerals via reflected light microscopy, Raman spectroscopy, and X-ray diffraction with a molybdenum tube. Using an electron microprobe, silicate minerals, oxides, glass, and sulfides were analyzed for their Cu concentration, as well as other major and trace element chemistry. Glass did not contain detectable Cu which precluded partition coefficient (Kd) calculations. Based on average Cu concentration for the non-sulfides, magnetite contains the most Cu, followed by (forsteritic) weathered olivine, pyroxene, olivine, plagioclase, and ilmenite. Copper sulfides were discovered in samples MB97-19 and MB97-76C with additional non-copper sulfides in MB97-76B. In conclusion, these results lay the groundwork for further investigation into potential copper sulfide reserves in the magma plumbing as with other flood basalt packages linked to economically important mineral deposits.

The origin of tourmaline nodules, bizarre spherical to irregular textures documented worldwide, remains a geologic mystery. Although previously described by numerous researchers, the physical and chemical parameters that govern their formation have yet to be resolved. Commonly containing tourmaline, quartz, and occasionally feldspar, nodules are surrounded by a halo of leucocratic host rock, and are typically eight to ten centimeters in diameter. Tourmaline nodules of the present study are contained within the Paleoproterozoic Scrubber Granite of the southern Gascoyne Complex in Western Australia. </p> <p>This study integrated field observations, nodule petrography, tourmaline crystal chemistry, tourmaline fluid inclusion analyses, whole rock chemistry of nodule cores, leucocratic halo zones and host granite zones, stable and radiogenic isotope signatures of tourmaline separates as well as comparisons with other tourmaline nodule studies to propose the most scientifically sound theory for the formation of tourmaline nodules in the Scrubber Granite. </p> Numerous nodule morphologies, including spherical and C-shaped nodules, along with other features such as tube-like nodules and tourmaline veins occur in massive, porphyritic, foliated and sheared phases of the Scrubber Granite. Microscopically, tourmaline displays prismatic, sub-rounded and massive textures. Microthermometric studies completed on tourmaline fluid inclusions revealed that the nodule-forming fluid contained 14 to 15 weight percent NaCl + CaCl2. Based on stable isotope studies and homogenization temperatures, fluid temperatures were constrained between 450 and 700¢ªC. The ¥ä18O and ¥äD concentrations of the nodule-forming fluid at this temperature range plot above the typical magmatic water field. Epsilon Nd values indicate that the tourmaline nodules of the Scrubber Granite may have been disturbed by a later metamorphic event.</p>Tourmaline nodules of the Scrubber Granite are herein proposed to have formed from the exsolution and rise of buoyant pockets or bubbles of volatile fluid derived from the crystallizing Scrubber Granite magma.

The origin of tourmaline nodules, bizarre spherical to irregular textures documented worldwide, remains a geologic mystery. Although previously described by numerous researchers, the physical and chemical parameters that govern their formation have yet to be resolved. Commonly containing tourmaline, quartz, and occasionally feldspar, nodules are surrounded by a halo of leucocratic host rock, and are typically eight to ten centimeters in diameter. Tourmaline nodules of the present study are contained within the Paleoproterozoic Scrubber Granite of the southern Gascoyne Complex in Western Australia. </p> <p>This study integrated field observations, nodule petrography, tourmaline crystal chemistry, tourmaline fluid inclusion analyses, whole rock chemistry of nodule cores, leucocratic halo zones and host granite zones, stable and radiogenic isotope signatures of tourmaline separates as well as comparisons with other tourmaline nodule studies to propose the most scientifically sound theory for the formation of tourmaline nodules in the Scrubber Granite. </p> Numerous nodule morphologies, including spherical and C-shaped nodules, along with other features such as tube-like nodules and tourmaline veins occur in massive, porphyritic, foliated and sheared phases of the Scrubber Granite. Microscopically, tourmaline displays prismatic, sub-rounded and massive textures. Microthermometric studies completed on tourmaline fluid inclusions revealed that the nodule-forming fluid contained 14 to 15 weight percent NaCl + CaCl2. Based on stable isotope studies and homogenization temperatures, fluid temperatures were constrained between 450 and 700¢ªC. The ¥ä18O and ¥äD concentrations of the nodule-forming fluid at this temperature range plot above the typical magmatic water field. Epsilon Nd values indicate that the tourmaline nodules of the Scrubber Granite may have been disturbed by a later metamorphic event.</p>Tourmaline nodules of the Scrubber Granite are herein proposed to have formed from the exsolution and rise of buoyant pockets or bubbles of volatile fluid derived from the crystallizing Scrubber Granite magma.