Thesis (Ph.D.)--Memorial University of Newfoundland, 2001. / Bibliography: leaves 232-244.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 379-383). Available also in a digital version from Dissertation Abstracts.

The long-term psychological effects of surviving a major disaster are poorly understood. A survey of survivors of the Piper Alpha oil platform disaster (1988) was undertaken to examine the role of factors relating to: the trauma; the survivors, and the survivors’ circumstances in relation to long-term outcome. Methods: Ten years after the disaster 78% (46/59) of the survivors were located, and, of these, 72% (33/46) agreed to be participate in a study conducted by questionnaire, diagnostic interview and semi-structured interview. In total, 61% of all survivors participated in this study. A further three individuals (7%) completed postal self-report measures. Results: High levels of physical disorder, general psychopathology and post-traumatic symptoms were reported. Twenty one percent (7/33) of the survivors who participated in the study still met the most stringent diagnostic criteria for PTSD over 10 years after the disaster; 73% met the same rule within three months of the disaster. Features such as physical injury, personal exposure to certain stressors during the trauma, survivor guilt, anger and employment difficulties were significantly correlated with long-term general and specific post-traumatic psychopathology and with social and occupational function. Features of the legal proceedings were also associated with long-term outcome. Whilst the media was experienced as intrusive, no statistically significant associations with long-term outcome were found. Treatment was generally accessible to participating survivors (97%) with non-professional help (82%) and outreach (69%; 25/36) widely used. Although many difficulties were experienced 61% of participants could identify some positive outcomes from the experience. Discussion: This study emphasises the need to consider a broad range of factors affecting outcome including the individual’s experience during a traumatic event, pre-existing stressors and factors relating to the response to the disaster and their environment. High rates of help-seeking were found to co-exist with high symptoms levels and this may relate to treatment effectiveness or failure to apply appropriate treatment in disaster populations. Attention to issues such as employment difficulties and compensation processes may improve survivor well-being in the long-term after disasters. Conclusions: This long-term follow-up of survivors of a major disaster has confirmed that the impact of a disaster is durable and extensive with psychological services required over prolonged periods.

Report (M.S.)--Virginia Polytechnic Institute and State University. M.S. 1991. / Vita. Abstract. Includes bibliographical references (leaves 72-73). Also available via the Internet.

Torpedo-shaped anchors serve as foundations for risers and floating structures in the deep-water marine environment. Such cone-tipped, cylindrical steel pipes, ballasted with concrete and scrap metal, penetrate the seabed by the kinetic energy they acquire during free fall. Estimation of the embedment depth is a crucial part of the design process in that the pull-out capacity is strongly dependent on the strength of the surrounding soil. This dissertation presents the development of a procedure based on a computational fluid dynamics (CFD) model for the prediction of the embedment depth of torpedo anchors. By means of a representation of the soil as a viscous fluid, the CFD model leads not only to the resisting forces on the anchor but the distributions of pressure and shear in the soil as well. These distributions are then imported in another computational tool for finite-element (FE) analysis of coupled deformation and fluid flow in porous media for further simulations of reconsolidation of the soil next to the anchor and, ultimately, short-term and long-term capacity estimation. This dissertation presents CFD results for torpedo-anchor installation in soil, comparisons with experimental data and, finally, results from FE analysis of soil reconsolidation and anchor pull-out. / text

Prêmio Petrobrás de Tecnologia, CNPq / O reinício do escoamento do fluido de perfuração é um grande problema em águas profundas e em poços de grande extensão como os do pré-sal. Dependendo da geometria do poço e de propriedades do fluido, picos de pressão significativos podem ocorrer comprometendo a estrutura do poço. O presente trabalho apresenta um modelo matemático para o escoamento compressível e transitório com o objetivo de prever a transmissão de pressão ao longo do poço e os picos de pressão durante o reinício do escoamento. O modelo baseia-se nas equações de conservação da massa e da quantidade de movimento que são resolvidas pelo método das características. Fluidos de perfuração são tratados como fluidos não newtonianos de Bingham e os efeitos viscosos são considerados através do conceito de fator de atrito. Os resultados do modelo são corroborados com alguns valores experimentais para o escoamento de um fluido newtoniano (água) e dois fluidos de perfuração. Estudos de casos são realizados com o propósito de verificar quais os efeitos das propriedades do fluido e da geometria na intensidade dos picos de pressão. A intensidade dos picos de pressão está relacionada ao fenômeno de superposição de ondas de pressão que se refletem nas extremidades da geometria. Aumentando o comprimento do poço, a viscosidade, a tensão limite de escoamento e a compressibilidade do fluido, ou diminuindo a massa específica e a área de uma das geometrias, proporciona-se uma dissipação mais rápida da onda de pressão. Quanto menor é a dissipação da onda de pressão por atrito viscoso, maior é a intensidade dos picos de pressão no fundo do poço. Para o caso com vazão constante na entrada como condição de contorno, a intensidade dos picos decresce com o aumento da razão de áreas, enquanto que para o caso com pressão constante, pode apresentar um valor mínimo. / The fluid flow start-up is a significant problem in deepwater and in long wells such as those of the Brazilian subsalt layers. Depending on the well geometry and fluid properties, significant pressure peaks may take place affecting the wellbore structure. This work presents a mathematical model to simulate the transient and compressible flow start-up of drilling fluids so as to predict the pressure transmission along the well and the pressure peak during the flow start-up. The model is based on the conservation equations of mass and momentum which are solved by the method of characteristics. Drilling fluids are treated as non-newtonian Bingham fluids and viscous effects are considered by using the friction factor approach. The model results are corroborated with some experimental values for a Newtonian (water) and two drilling fluids. Case studies are conducted to verifying how the magnitudes of the pressures peaks are affected by the fluid properties and the well geometry. The magnitude of the pressure peak is related to the phenomenon of superposition of pressure waves that are reflected in the ends of the drillpipe-well geometry. Either increasing the well length, viscosity, yield stress and fluid compressibility, or decreasing the fluid density and the cross-sectional area, the pressure wave is faster dissipated. The lower the pressure wave dissipation by viscous friction larger is the magnitude of the pressure peak in the borehole. For constant inlet flow rates as boundary condition, the magnitude of the peaks decreases as the ratio of the pipe and well cross-sectional areas increases, whereas for constant inlet pressure cases, this peak reaches a minimum value.

Thesis (M. S.)--Texas A&M University, 2004. / Vita. Abstract. "Major Subject: Petroleum Engineering" Includes bibliographical references.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 124-127. / by Enrique J. Laya. / M.S.

[Truncated abstract] The Arabian Gulf oil and gas production reserves have made it one of the world's strategic producers since early 1960s, with many of the existing platforms stretched beyond their original design life. Advances in drilling technology and reservoir assessments have extended the requirement for the service life of those existing platforms even further. Extension of the life span of an existing platform requires satisfactory reassessment of its various structural components, including piled foundations. The American Petroleum Institute Recommended Practice 2A (API RP2A) is commonly used in the Arabian Gulf for reassessment of existing platforms. The API guidelines have been developed for conditions in the Gulf of Mexico, the waters off Alaska and the Pacific and Atlantic seaboards of the USA. However, the Arabian Gulf conditions are fundamentally different to those encountered in US waters. Hence, there is a need to develop guidelines for reassessment of existing offshore structures to account for the specific conditions of the Arabian Gulf. This thesis performs statistical analyses on databases collected during this research from existing platforms to calibrate relevant load and resistance factors for the required guidelines. The developed guidelines are based on established approaches used in developing international codes and standards such as API RP2A-LRFD. The outcome of this research revolves around the following three main issues: 1. Calibration of resistance factors for axial capacity of piles driven in the carbonate soils API RP2A (1993, 2000) does not quantify limiting soil parameters for piles driven in carbonate soils and provides a single factor to predict the capacity of piled foundations. This research identifies a set of limiting engineering parameters and calibrates corresponding capacity reduction factors to predict axial capacity of driven piles in the carbonate soils of the Arabian Gulf. ... This contrasts with Section 'R' of API RP2A (1993, 2000), which focuses on extreme environmental conditions when performing reassessment. The probabilities of failure considered in this research do not include errors and omissions (controlled by quality assurance procedures) or material deterioration (controlled by choice of materials, detailing, protective devices, and inspection and repair procedures) or reliability-based maintenance. Addressing operating overload conditions requires attending to two issues, namely the capacity of piles driven in carbonate soils and OALL, which have been addressed in this research. The operational overload situation is likely to occur during shutdown condition or during drilling or work over activities where significant OALL are usually applied to platform decks. Such operational overload can be managed by placing signs at various open areas on the platform nominating the maximum load limits (kPa), introducing procedures that ensure that maximum load limits are not exceeded during operation and management of human behavior by reinforcing the importance of following the procedures. The outcomes of this research are expected to have a profound influence on reassessment of existing platforms in the Arabian Gulf.

Petrobras / No processo de perfuração de poços de petróleo e gás o controle da pressão é uma importante tarefa. Se a pressão no interior do poço estiver abaixo da pressão de poros, um influxo da formação pode ocorrer, fenômeno denominado de kick. Se o influxo não for controlado pode ocorrer um fluxo descontrolado da formação para a superfície (blowout). As pressões de fechamento são utilizadas para calcular a pressão do reservatório, entretanto, o caráter viscoplástico do fluido de perfuração atenua as pressões medidas. No presente trabalho, é apresentada uma modelagem matemática e numérica para prever a propagação de pressão ao longo do poço durante um influxo de gás (kick). Considerou-se a compressibilidade e o comportamento viscoplástico do fluido de perfuração, modelando-o como Plástico de Bingham. O escoamento é considerado unidimensional, laminar, transiente, isotérmico e homogêneo. A solubilidade do gás no fluido de perfuração é desconsiderada e o gás é modelado como um gás real. O fluxo da formação para o interior do poço é tratado através da lei de Darcy. Os balanços de massa e de quantidade de movimento para a mistura formam um sistema de equações diferenciais parciais hiperbólicas, tendo como incógnitas a pressão e a velocidade, as quais são resolvidas pelo método das características. Consideram-se dois casos de estudo: o kick dinâmico e o kick estático. A obtenção dos campos de velocidade e pressão ao longo do poço é realizada através de um programa computacional desenvolvido em linguagem FORTRAN. Posteriormente, aferiu-se os resultados obtidos pelo modelo desenvolvido comparando-os com solução analítica e dados experimentais. Os resultados apresentam que quanto maior a tensão limite de escoamento, menor é a transmissão de pressão e que se a pressão do reservatório não for grande o suficiente, não há ganho de volume de fluido nos tanques de lama. / In the process of drilling oil and gas wells the pressure control is an important task. If the pressure inside the well is smaller than the formation pressure, an influx of the formation may occur, phenomenon denominated as kick. If the influx is not controlled there may be an uncontrolled flux from the formation to the surface (blowout). The closing pressures are used to calculate the formation pressure, however, the viscoplastic character of the drilling fluid reduces the pressures measured on the surface. This current work presents a mathematical and numerical modeling to predict the pressure propagation along the well during a gas influx (kick). The compressibility and the viscoplastic behavior of the drilling fluid were considered, modeling it as a Bingham Plastic. The flow is considered as one-dimensional, laminar, transient, isothermal and homogeneous. The solubility of the gas in the drilling fluid is disregarded and the gas is modeled as a real gas. The flux of the formation into the wellbore is treated by Darcy’s law. The balance equations of mass and momentum for the mixture result in a system of hyperbolic partial differential equations, having as unknowns the pressure and the velocity, which are solved by the method of characteristics. Two study cases were considered: the dynamic kick and the static kick. The pressure and velocity fields along the well are obtained by a computer program developed in FORTRAN language. Afterwards, the results obtained from the model developed were assessed by comparing to analytic solution and experimental data. The results present that the bigger the yield stress is, the smaller is the pressure transmission and that if the formation pressure is not high enough, there is no pit-gain in the mud tanks.