No description available.

Undulating well trajectories are often drilled to improve length exposure to rock formations, target desirable hydrocarbon-saturated zones, and enhance resolution of borehole measurements. Despite these merits, undulating wells can introduce adverse conditions to the interpretation of borehole measurements which are seldom observed in vertical wells penetrating horizontal layers. Common examples are polarization horns observed across formation bed boundaries in borehole resistivity measurements acquired in highly-deviated wells. Consequently, conventional interpretation practices developed for vertical wells can yield inaccurate results in HA/HZ wells. A reliable approach to account for well trajectory and bed-boundary effects in the petrophysical interpretation of well logs is the application of forward and inverse modeling techniques because of their explicit use of measurement response functions. The main objective of this dissertation is to develop inversion-based petrophysical interpretation methods that quantitatively integrate logging-while-drilling (LWD) multi-sector nuclear (i.e., density, neutron porosity, photoelectric factor, natural gamma ray) and multi-array propagation resistivity measurements. Under the assumption of a multi-layer formation model, the inversion approach estimates formation properties specific to a given measurement domain by numerically reproducing the available measurements. Subsequently, compositional multi-mineral analysis of inverted layer-by-layer properties is implemented for volumetric estimation of rock and fluid constituents. The most important prerequisite for efficient petrophysical inversion is fast and accurate forward models that incorporate specific measurement response functions for numerical simulation of LWD measurements. In the nuclear measurement domain, first-order perturbation theory and flux sensitivity functions (FSFs) are reliable and accurate for rapid numerical simulation. Albeit efficient, these first-order approximations can be inaccurate when modeling neutron porosity logs, especially in the presence of borehole environmental effects (tool standoff or/and invasion) and across highly contrasting beds and complex formation geometries. Accordingly, a secondary thrust of this dissertation is the introduction of two new methods for improving the accuracy of rapid numerical simulation of LWD neutron porosity measurements. The two methods include: (1) a neutron-density petrophysical parameterization approach for describing formation macroscopic cross section, and (2) a one-group neutron diffusion flux-difference method for estimating perturbed spatial neutron porosity fluxes. Both methods are validated with full Monte Carlo (MC) calculations of spatial neutron detector FSFs and subsequent simulations of neutron porosity logs in the presence of LWD azimuthal standoff, invasion, and highly dipping beds. Analysis of field and synthetic verification examples with the combined resistivity-nuclear inversion method confirms that inversion-based estimation of hydrocarbon pore volume in HA/HZ wells is more accurate than conventional well-log analysis. Estimated hydrocarbon pore volume from conventional analysis can give rise to errors as high as 15% in undulating HA/HZ intervals. / text

Thesis (M.T.S.C.)--Miami University, Dept. of English, 2005. / Title from first page of PDF document. Document formatted into pages; contains [1], vii, 65 p. : ill. Includes bibliographical references.

Peat from the temperate regions has been used for paleoenvironmental reconstruction using diverse proxies for over a century now. Peat is rare and severely understudied in the tropics. The montane peat bogs of the Nilgiris, southern India have been found to preserve global climatic signals including the Holocene Optimum and the Last Glacial Maximum (LGM). At Sandynallah, one of the oldest peat accumulations in the world at >40 kyr BP, we had undertaken a high resolution paleoenvironmental reconstruction using multiple proxies which are yet to be evaluated in the tropical context. The study consists of 3 main objectives, i. Establishing an accurate high resolution chronology for the peat profile using radiocarbon dating, ii. Extracting vegetation and climate information from C/N ratio and Rock-Eval indices and iii. Using elemental profiles to establish the utility of inorganic geochemical proxies for processes such as weathering and dust transport. High resolution chronology for the site was built using Accelerator Mass Spectrometry (AMS) radiocarbon dates. To improve accuracy of the age-depth model, we also tested 4 samples for the effects of the AAA (Acid-Alkali-Acid) extraction method, the most common pre-treatment method for peat in the world. We compared ages on bulk samples (acid washed) and AAA treated samples from 4 different depths. We find that for all depths, the ages of the untreated samples do not lie within the internal uncertainty window and differ from the AAA treated sample age by at least an order of magnitude of the internal error, if not more. Based on these results we argue that the internal error should be used in conjunction with a reliable estimate of external error in an age-depth model for more realistic dating of paleoclimatic events. C/N ratios were explored for their paleoclimatic potential in conjunction with Rock-Eval indices and it was found that decomposition in tropical peat, as opposed to temperate peat, may not be sensitive to climatic perturbations. Inorganic geochemical proxies were also evaluated through this study. We see that the major and trace elements, except the lanthanide series do not show many significant trends for paleoenvironmental interpretation. But the lanthanides show some promise for identifying potential sources of dust and weathered material. Our study has addressed the gap in knowledge about the utility of recent geochemical proxies in tropical peat and has attempted to provide a solution to improve reliability in constructing age-depth models.

No description available.

Cette thèse est une enquête d'histoire et de philosophie des sciences sur l'hypothèse Gaïa (HG) proposée par Lovelock et Margulis dans les années 1970. L'examen historique de l'élaboration d'HG et de sa très riche réception dans diverses disciplines scientifiques (climatologie, biogéochimie, géochimie, biologie de l'évolution, écologie et sciences de la complexité) et au sein des mouvements environnementalistes nous conduit à montrer qu'une ambiguïté majeure sur le statut d'HG grève la littérature : qu'est-ce qu'HG ? Nous montrons qu'HG a été considérée tantôt comme une hypothèse, tantôt comme une théorie, tantôt comme un programme de recherche, tantôt comme une philosophie de la nature. Chacune de ces lectures est ensuite examinée. Nous proposons une caractérisation épistémologique et historique d'HG montrant qu'HG ne doit pas être interprétée comme une hypothèse devant être confrontée de manière directe aux faits, mais comme une théorie élaborée avec des modèles. Nous clarifions alors le rôle et le statut méthodologique des modèles et théories d'HG ainsi que les concepts et hypothèses fondamentales qui les sous-tendent. La reconnaissance de Gaïa comme un système constitué des vivants et de l'environnement avec lequel ils interagissent a été l'origine de la constitution d'un nouveau programme de recherche: les sciences du système Terre. Nous proposons une histoire et une caractérisation de ce programme, repérons les déplacements philosophiques qu'il a opérés à propos des concepts de vie, d'environnement et de nature puis analysons les liens entre les conceptions que Lovelock a de Gaïa et les prescriptions environnementales qu'il a prononcées au nom de Gaïa. / The Gaia hypothesis (GH) proposed in the 1970's by Lovelock and Margulis is here analyzed from a history and philosophy of science perspective. The historical analysis of GH's elaboration and rich reception across various disciplines (climatology, biogeochemistry, geochemistry, evolutionary biology, ecology and complexity sciences) and within environmentalist movements leads me to argue that a major ambiguity plagues the relevant literatures: what is GH? I show that GH has been considered as a hypothesis, as a theory, as a research program, or as a philosophy of nature. Each of these interpretations is then analyzed. An epistemological and historical characterisation of GH shows that GH should not be interpreted as a hypothesis which ought to be confronted directly to empirical facts, but as a theory elaborated with models. I elucidate the methodological role and status of GH's models and theories before clarifying the concepts and expliciting the fundamental hypotheses underlying these models and theories. The recognition of Gaia as a system constituted of living organisms and the environment with which they internet led to the constitution of a new research program: the Earth system sciences. I offer a history and a characterisation of this research program, specify the philosophical shifts it brought about concepts such as life, the environment and nature and I analyze the relationships between Lovelock's conceptions of Gaia and the environmental prescriptions he pronounced in the name of Gaia.

Orientador: Silvia Fernanda de Mendonça Figueirôa / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-19T00:12:25Z (GMT). No. of bitstreams: 1 AssisJunior_Heitorde_D.pdf: 8773337 bytes, checksum: 79aa03cc23c97d2f3e92199e46a93f24 (MD5) Previous issue date: 2011 / Resumo: Esta tese de doutorado traz informações a respeito do pintor José dos Reis Carvalho e sua produção artística. Fez parte desta pesquisa as relações com Debret e com a Comissão Científica de Exploração das Províncias do Norte, ou seja, as influências do seu professor na Academia Imperial de Belas Artes e sua participação na primeira expedição científica genuinamente brasileira promovida pelo Instituto Histórico e Geográfico Brasileiro. Reis Carvalho realizou diversas obras de cunho etnográfico documentando vestes e fisionomias dos habitantes do Rio de Janeiro, de onde também retratou edificações e equipamentos urbanos, dos quais, sob a influência do mestre Debret, destacou aspectos construtivos, técnicos e de funcionamento, assim como seus operadores. Durante a Comissão Científica de Exploração das Províncias do Norte, da qual participou entre fevereiro de 1859 até julho de 1861, realizou diversos desenhos e pinturas, orientados pelo botânico Freire Alemão (1797- 1874), pelo zoólogo Manoel Ferreira Lagos (1817-1871) e pelo geólogo Guilherme Schüch Capanema (1824-1908). Suas imagens parecem ilustrar diversas passagens dos escritos de Capanema e dos manuscritos de Freire Alemão, nas quais estes descrevem desde rochas e paisagens naturais, até vários tipos de cercas, construções de casas e mesmo, formas utilizadas pelos sertanejos para pendurar suas redes. Durante aquela empreitada, principalmente a aquarela foi utilizada na retratação dos elementos observados, de natureza geológica, etnográfica, técnica, botânica ou zoológica. Suas imagens incluem paisagens naturais que ressaltam características geológicas e botânicas, particularidades anatômicas de espécimes vegetais e animais, construções e povoações. Seus tipos humanos são mostrados sem idealização das fisionomias e realizando tarefas diárias, mediante utilização de artefatos e técnicas particulares de manejo. A confrontação de imagens permite notar que José dos Reis Carvalho também foi influenciado por pintores estrangeiros que acompanharam e participaram de expedições comandadas por cientistas viajantes durante o século XIX. Portanto, seu perfil iconográfico vai muito além daquele normalmente encontrado em bibliografias que o tratam como pintor de flores e naturezas mortas / Abstract: This doctorate thesis brings information about the painter José dos Reis Carvalho and his artistic production. It was part of this research his relations with Debret and with the Comissão Científica de Exploração das Províncias do Norte (Scientific Comission of Exploration of the Northern Provinces) - the influences of his teacher at the Academia Imperial de Belas Artes (Imperial Academy of Fine Arts) and his participation in the first scientific expedition genuinely Brazilian sponsored by the Instituto Histórico e Geográfico Brasileiro (Brazilian Institute of History and Geography). Reis Carvalho has produced many works of etnographic features documenting clothes and physical characteristics of the inhabitants of Rio de Janeiro where he has also pictured buildings and urban equipments, of which, under Debret's influence, has pointed out aspects such as constructive, technical, and working, as well as their operators. When he participated in the Comissão Científica de Exploração das Províncias do Norte (Scientific Comission of Exploration of the Northern Provinces), between February 1859 and July 1861, he produced many drawings and paintings oriented by the botanist Freire Alemão (1797-1874), by the zoologist Manoel Ferreira Lagos (1817-1871), and by the geologist Guilherme Schüch Capanema (1824-1908). His images seem to illustrate several passages of Capanema's writings and of Freire Alemão's manuscripts, in which, these describe from rocks and natural landscapes to various kinds of fences, house structures, and even different ways the country people used to hang their hammocks. During that task the water color was most used to picture the observed elements of geologic nature. His images include natural landscapes that emphasize geologic and botanic features of vegetal and animal specimens, buildings and villages. His human types are shown without physiognomic pattern doing every day tasks and using artifacts and special handling technics. The confrontation of images allows the observation that José dos Reis Carvalho was also influenced by foreign painters who attended the expeditions led by traveller scientists during the nineteenth century. Therefore, his iconographic profile goes much beyond of that usually found in bibliographies that place him as a painter of flowers and still life / Doutorado / Ensino e Historia de Ciencias da Terra / Doutor em Ciências

Local site conditions are known to influence ground motion during earthquake events and increase the severity of damage. Data from earthquakes are useful to study the response but they are available only from active regions. Ubiquitous ambient vibrations on the other hand offer a more practical approach to quantify site responses. This thesis explores the use of various methods for obtaining site responses. The primary area of study is the Kachchh rift basin, NW India, a Mesozoic rift that features significant lateral variations in surface geology and has experienced ground responses during 1819 and 2001 earthquakes. The Mw 7.6, 2001 event was followed by hundreds of aftershocks, which were recorded by temporary networks. In this study we have used earthquake signals as well as ambient vibrations to understand site response in various parts of the basin. In addition we have collected data from a few sites from the Indo-Gangetic plains and Kathmandu valley, both affected by large earthquakes, 1934 the M ~ 8 (Bihar) and 2015, Mw 7.8 (Nepal). Velocity and acceleration records from a network of eight stations in the Kachchh Rift were used to evaluate site responses using Standard Spectral Ratio (SSR) and Horizontal to Vertical spectral ratio (HVSR-E) methods. Ambient vibrations were analyzed following Nakamura’s H/V method (HVSR-AV), for data collected from 110 sites that represent different field conditions within the Kachchh Rift. Fundamental resonance frequency (f0) varied between 0.12 – 2.30 Hz, while the amplification factor (A0) was in the range of 2.0 – 9.1. We found that higher A0 and liquefaction index (Kg) values were mostly associated with higher liquefaction potential. Using a close network of stations, we studied the role of site response in damage to the Bhuj city that suffered maximum damage in 2001; our results suggest that site response was not a significant factor. Studies based on passive data were complemented by Multi-channel Analysis of Surface Waves (MASW) to map shear wave velocities of the various subsurface units up to depths of 10m (Vs10) and 30m (Vs30). Our results imply average Vs could be a good proxy to characterize site amplifications where sediment thicknesses are shallow. Power law relationship between f0 and thickness (h) suggest a strong positive correlation (r = 0.89) adding credence to HVSR-AV method, making it a cost-effective alternative to MASW to infer site conditions. Further, to understand the influence of topography on site effects, we analyzed data from hills, valleys and their edges, both from the Kachchh rift and Kathmandu valley. Sites on the edges of valleys showed multiple, fuzzy peaks in the low frequency range (< 1 Hz) and broad peaks attributable to sites prone to higher damage. Spectrograms generated through Huang-Hilbert Transforms (HHT) suggested focusing of energy in narrow frequency bands on the edges, while valleys tend to scatter energy over wide frequencies. Although our current results are based on limited observations, we recognize spectral analysis as a powerful tool to quantify site effects in regions with significant topography. It is known that coseismic liquefaction could lead to nonlinear behavior wherein the near-surface soil layer loses its shear strength, causing a reduction of its fundamental resonance frequency. We used data from selected sites of coseismic liquefaction to highlight the significance of nonlinear effects in site response. Earthquake signals and ambient vibrations from Umedpur, a region that experienced intense liquefaction during 2001 were used in this analysis. Here we followed an empirical decomposition method based on HHT and signals were decomposed as many intrinsic mode functions (IMFs) that showed characteristic peaks for events of various values of PGAs. Thus, the first IMF for events with relatively higher PGAs (0.03g) showed distinct peaks for the S wave coda part, which were not noted for those with lower PGA (0.01g). These observations in a region of coseismic liquefaction are useful in developing models for quantifying nonlinear behavior. In conclusion, site response studies using different types of data and processing techniques in regions affected by recent earthquakes brings out the scope and limitations of each of these sets of data and techniques. This study suggests that ambient vibrations provide reasonable estimates of site response and can be reliably used in regions where earthquake data are not available.

Surface water hydrology is a deeply studied subject, yet there are barely any studies concerning surface water connectivity, neither micro- nor macro scale. With the explosive development of GIS over the past decade, tools for measuring and analysing rivers and lakes are inumerable. Light detection and ranging (LiDAR) has also seen tremendous improvements over the years. This study uses high resolution digital elevation models and georeferenced aereal photographs to carry out a detailed GIS-analysis of river-lake connectivity in three catchments in Västerbotten, Sweden: Bjurbäcken, Hjuksån and Gargån. Hjuksån is located beneath the highest coast line (HCL) wheras the other catchments are located above this line. A second pupose of the study is also to test if lake size varies above and below HCL. Lakes were digitized at 1:2000 scale and the rivers were digitized and categorized in Strahler stream order using tools in ArcGIS Pro. The data from the study was compared to data from the Swedish Meteorological and Hydrological Institute (SMHI), as well as data from international studies. The results show a surface water connection of 71,4% for Bjurbäcken, 62% for Hjuksån and 73,1% for Gargån. Comparing this data to data from SMHI results in a lowering of the surface water connection by 20 percentage points för Bjurbäcken, 30,3 for Hjuksån and 8,2 for Gargån. Lake size was tested between the catchments using an ANOVA, yielding a significant difference between Hjuksån and Bjurbäcken as well as Hjuksån and Gargån, backing up the hypothesis that HCL affects lake size.