Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Includes bibliographical references (p. 294-299).

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Carboxylated macromolecules such as alginate and glycoproteins are abundant components of modern shallow marine sediments where they are secreted by bacteria and marine infauna. Both organic compounds are proton and metal reactive; hence, they have the potential to facilitate metal sorption and biomineralization reactions. In this study, lab experiments were coupled to field-based sampling to assess the role that these compounds play in microbial mats, with particular emphasis on the hypersaline lagoons of Los Roques, Venezuela. Here I applied a surface complexation approach to model proton and Cd adsorption behaviour of both uronic acid-rich alginate and mucin. Measured total site concentrations, available for metal adsorption, demonstrate that these compounds have the potential to induce metal partitioning in early diagenetic microenvironments. Field results from Venezuela are consistent with Mg- and trace metal- enrichment that follows a likely correlation with the degradation states of microbial biomass trapped during accretion of modern microbialites.

The Upper Devonian Grosmont shelf complex is the worlds largest heavy oil deposit hosted in carbonates, with an estimated >50 billion cubic meters (318 to probably 406 bbls) of initial volume in place. At present the Grosmont is not yet under production. This study involves log interpretation, core examination; facies description; strontium, sulphur, carbon, and oxygen isotope analysis. The Grosmont is subdivided into four shallowing-upward cycles. Most Hondo evaporites are part of the Upper Grosmont 3 and Lower Grosmont and were deposited in a series of small, shallow subaqueous brine ponds or in an extensive lagoon. In the eastern part of the area, the Hondo appears to be dissolved resulting in solution-collapse breccias. Other diagenetic processes that were important in shaping the present reservoir characteristics were pervasive dolomitization and dolomite recrystallization, fracturing, and karstification.

The Maldives atolls, the very top of one of the largest modern carbonate platforms, occupy the central and largest part of the Chagos-Laccadives ridge located in the equatorial Indian Ocean. In the central part of the archipelago, the large atolls form two parallel north-south relatively continuous chains surrounding an internal basin, the Inner Sea, with water depths not exceeding 550 m. The Maldives carbonate system, uniquely evolved through a combination of global sea level fluctuations, subsiding history, and more regional seasonally varying monsoon circulation. Although the long-term evolution of this system is relatively well-established, the understanding of the detailed evolution of the Maldives carbonate edifice in the last 5 million years has remained limited. The latest phase of its stratigraphic evolution is explained by a shift from a well-developed Miocene-Pliocene progradational pattern to a mostly late Pliocene-Quaternary aggradational depositional signature. This last aggradation phase, forming the atolls the way we know them today, consists of stacked inner neritic limestone sequences, separated by a series of exposure horizons. The succesive periods of atoll exposure and re-flooding are recorded in the Inner Sea by late Pliocene-Quaternary glacial/interglacial clearly cyclic deposition of periplatform oozes. This cyclic sedimentary pattern also appears in the internal prograding geometry of carbonate drifts in the Inner Sea. A200 m-thick deep carbonate sediment drift was first observed on a Shell E-W seismic line north of Gaafaru Falhu atoll in the NE corner of the Maldives Inner Sea, in a range of water depths from ~300 to 500 m. During the NEOMA 2007 research cruise on the RV Meteor lead by Universität Hamburg, the deep water sandy drift in the area north of Gaafaru Falhu atoll and an adjacent deeper muddy drift was extensively surveyed via 12 kHz multibeam bathymetry, a 4 kHz sub bottom profiler (Atlas Hydrographics), multi channel high resolution seismics, and three box and piston cores. My study focuses on understanding the Plio-Quaternary overall evolution of the set of adjacent sandy and muddy drifts, just north of Gaafaru Falhu Atoll. The sandy and muddy drift interconnected internal geometries observed in the available seismic data sets are integrated into a sequence stratigraphic framework. Analyses of two piston cores collected from the upper part of the muddy drift and a box core from the top of the sandy drift determine the overall downcore lithology variations and made possible the development of high-resolution chrono and cyclo-stratigraphies. In the muddy drift periplatform sequence, downcore cyclic variations in, (1) sediment coarse fraction, (2) Sr counts as proxy for atoll-derived fine aragonite, (3) planktic foraminifer oxygen stable isotope composition, in addition to carbonate preservation and biostratigraphic markers, were determined. These downcore lithologic and geochemical variations in the muddy drift were tied to the seismic lines imaging the sandy-muddy drifts to resolve the timing of the carbonate sandy drift establishment and its overall evolution. Based on this aforementioned interpretation, the results of my research document the nature and timing of the longer-term evolution of the sandy and muddy drifts over multiple glacial-interglacial sea level cycles in the last 3 million years. Once the timing of the drift was determined, the prograding internal architecture of the sandy drift was examined and interpreted in the context of the relatively well-established Plio-Pleistocene sea level fluctuations and the bottom current variations

Carbonates invariably have small (micron) to large (centimeter) scale heterogeneities in flow properties that may cause the effects of injected acids to differ greatly from what is predicted by a model based on a homogenous formation. To the best of our knowledge, there are neither theoretical nor experimental studies on the effect of large scale heterogeneities (vugs) on matrix acidizing. The abundance of carbonate reservoirs (60% of the world?s oil reserves) and the lack of a detailed study on the effect of multi-scale heterogeneities in carbonate acidizing are the main motivations behind this study. In this work, we first present a methodology to characterize the carbonate cores prior to the core-flood acidizing experiments. Our approach consists of characterization of the fine-scale (millimeter) heterogeneities using computerized tomography (CT) and geostatistics, and the larger-scale (millimeter to centimeter) heterogeneities using connected component labeling algorithm and numerical simulation. In order to understand the connectivity of vugs and thus their contribution to flow, a well-known 2D visualization algorithm, connected component labeling (CCL), was implemented in 3D domain. Another tool used in this study to understand the connectivity of the vugs and its effect on fluid flow is numerical simulation. A 3D finite difference numerical model is developed based on Darcy-Brinkman formulation (DBF). Using the developed simulator a flow-based inversion approach is implemented to understand the connectivity of the vugs in the samples studied. After multi-scale characterization of the cores, acid core-flood experiments are conducted. Cores measuring four inches in diameter by twenty inches in length are used to decrease the geometry effects on the wormhole path. The post acid injection porosity distribution and wormhole paths are visualized after the experiments. The experimental results demonstrate that acid follows not only the high permeability paths but also the spatially correlated ones. While the connectivity between the vugs, total amount of vuggy pore space and size of the cores are the predominant factors, spatial correlation of the petro-physical properties has less pronounced effect on wormhole propagation in acidiziation of carbonates. The fact that acid channeled through the vugular cores, following the path of the vug system, was underlined with computerized tomography scans of the cores before and after acid injection. This observation proposes that local pressure drops created by vugs are more dominant in determining the wormhole flow path than the chemical reactions occurring at the pore level. Following this idea, we present a modeling study in order to understand flow in porous media in the presence of vugs. Use of coupled Darcy and Stokes flow principles, known as Darcy-Brinkman formulation (DBF), underpins the proposed approach. Several synthetic simulation scenarios are created to study the effect of vugs on flow and transport. The results demonstrate that total injection volume to breakthrough is affected by spatial distribution, amount and connectivity of vuggy pore space. An interesting finding is that although the presence and amount of vugs does not change the effective permeability of the formation, it could highly effect fluid diversion. We think this is a very important observation for designing of multi layer stimulation.

Polycarbonates are a type of engineering thermoplastic that have countless uses in modern society. Currently, the major industrial production of polycarbonates involves the polycondensation of a diol and phosgene or phosgene derivative. Though there are many advantages to this process, it creates large amounts of waste and requires dangerous chemicals in order to proceed. Over the past four decades, the coupling of CO_(2) and epoxides has grown into a viable, greener alternative for the production of select polycarbonates. The byproduct of this reaction, cyclic carbonates, also have use as polar, high boiling solvents. This dissertation will be divided into three parts. First, the coupling of indene oxide and CO_(2) to form poly(indene carbonate) and cis-indene carbonate will be discussed. Poly(indene carbonate) has the highest Tg yet reported for polymers derived CO_(2) /epoxides coupling, up to 138degreeC. Polycarbonate production requires the use of (salen)Co(III) catalysts and low temperatures, though some cyclic carbonate production is still observed. Selective production of poly(indene carbonate) has been achieved through the use of bifunctional cobalt(III) complexes. The effects of temperature and cosolvent choices on polymer production will be thoroughly discussed. Though polycarbonate is the kinetic product from the coupling of CO_(2) and epoxides, the thermodynamic product is cyclic carbonate. There are six potential mechanisms that yield this undesired byproduct, though there is limited research into which pathways are the most active during polymerization reactions. Temperature-dependent kinetic studies were performed to obtain the activation parameters for the direct, polymer-free coupling of cyclopentene oxide, indene oxide, 1,2-butylene oxide, and styrene oxide with CO_(2) utilizing (salen)CrCl/nBu_(4)NCl to yield their corresponding cyclic carbonates. Additionally, the metal-free backbiting of the singly-coupled styrene oxide/CO_(2) intermediate was simulated utilizing the halohydrin 2-chloro-1-phenylethanol. Finally, the coupling of cyclopentene oxide with carbon disulfide to yield poly[thio]carbonates and cyclic [thio]carbonates utilizing (salen)CrCl/PPNX will be discussed. In each reaction, scrambling of the oxygen and sulfur atoms in both the polymeric and cyclic product is observed. Long reaction times lead to increased amounts of [thio]ether linkages and therefore polymers with lower glass transition temperatures. Insights into both the coupling and scrambling mechanisms will be presented.

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