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Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1938. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed April 20, 2010) Includes bibliographical references (p. 2-4) and index (p. 116-119).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 83-88).

Thesis (Ph.D.)--University of Iowa, 2006. / Supervisors: Larry J. Weber, George Constantinescu. Includes vita. Includes bibliographical references (leaves 220-222).

The global offshore oil and gas industry is constantly challenged with complex operational activities, increasing uncertainties, strict regulations and delicate health, safety and environmental issues. That has made offshore deepwater drilling operation the most time sensitive activity in the upstream oil and gas industry with high probabilities of cost and time overrun. Unfortunately, the current cost estimation models are not robust enough to deal with the multi-variables associated with cost overrun in the offshore deepwater drilling industry in the Sub-Sahara Africa. This study therefore developed a mathematical model that can give accurate estimations with limited data, precisely capture risk elements and factor probability results of all the possible cost variables in the offshore deep-water drilling operations. The study combined Bayesian approach with Activity-based costing (ABC) model to address the limitations of most existing models using primary data collected and secondary data extrapolated from past literatures, published official drilling data and companies’ financial and operational reports. The integrated model showed promising results when tested against three offshore fields’ data across three different countries (Erha-Nigeria, Jubilee-Ghana and Luanda-Angola). Findings from the analysis of the three fields showed cost estimates to be 10% more accurate than the estimates from existing cost estimation models in Sub-Sahara Africa. Further analysis also demonstrated the ability of the model to reduce the regional cost overrun from about 40% to 20%, thereby underlining the efficacy of the model in estimating offshore drilling cost. The strengths, weaknesses as well as the implications of using the model were also discussed. Additionally, the study developed an improved elicitation framework and guidelines to help facilitate cost estimation in the offshore deep-water drilling operations based on the Bayesian approach. The developed elicitation process was used to collect the primary data for this work and generated probabilistic response on the known unknowns and unknown unknowns’ variables in the oil and gas industry Finally, the research analysed and produced findings on cost reduction techniques for the offshore drilling industry.

The UK sector of the North Sea is a mature oil and gas basin subjected to some of the harshest offshore environments with a majority of the oil and gas installations approaching or having exceeded their original design life, often specified as 25 years. It is likely that the operation of these installations will continue for a substantial period in the foreseeable future. However, the ageing nature of these installations present significant challenges to the delivery of high standards of health and safety required by the UK Health and Safety Executive. The issue of ageing installations has been shown to be an important factor in offshore incidents and accidents, leading to an increased risk of accidental loss of hydrocarbon and failures due to equipment deterioration. Two major hazards resulting from ignition of accidental hydrocarbon release are fires and explosions. Failure to minimise the effects of fires and explosions can bring about significant damage to the structural integrity of offshore installations and pose a risk to personnel safety as evidenced by the 1988 Piper Alpha Disaster and the 2010 Deepwater Horizon Explosion and Oil Spill. This thesis presents a practical tool that can be used to predict the costs, risks and service reliability of any given asset management policy for an offshore oil and gas installation. The tool is implemented using a standard Petri Net technique with already adopted and newly proposed high level extensions, and fluid flow modelling technique. The tool is further divided into two sub models that work in conjunction with one another: (1) the Petri Net based Offshore Safety System Degradation and Maintenance Model and (2) the Offshore Fire and Explosion Model based on fluid flow modelling techniques. The aim of the Offshore Safety System Degradation and Maintenance Model is to concurrently simulate the degradation, failure, inspection and maintenance of four safety systems which includes the fire and gas detection system, process isolation, process blowdown, and the deluge system. Simulation of the model generates a variety of statistics such as the estimated operational costs and unavailability associated with implementing any given asset management policy. The Offshore Fire and Explosion Model is then used to model the occurrence of a hydrocarbon leak from a process vessel located within three enclosed modules; wellhead, separation and compression, of an offshore installation. The aim of this model is to predict the frequencies of fires and explosions in the event that the safety systems previously modelled in the Offshore Safety System Degradation and Maintenance Model fail to function on demand in the presence of an ignition source. The model utilises fluid flow modelling to calculate parameters such as the hydrocarbon discharge rate, gas cloud build-up and dispersion, oil-pool build-up and reduction. These parameters can then be used to predict the magnitude of the fires and explosions in terms of the flame length produced in the event of a fire and the overpressures generated in the event of an explosion. The results and statistics generated are highly beneficial to offshore asset operations managers as they can be used to predict the number of maintenance interventions necessary to ensure safety systems are in an acceptable condition. From this, associated costs can be determined enabling offshore managers to allocate resources and budget accordingly. Finally, an optimisation study is carried out using Genetic Algorithm to identify the optimum inspection, maintenance and repair strategy for the offshore safety systems with an acceptable risk level. The methodology presented in this research considers the offshore safety systems and the processes described above in more detail compared to previous literature associated with asset management offshore oil and gas installation. Additionally, the research demonstrates the suitability of Petri Nets for integrating fire and explosion modelling within the asset management framework which is first of its kind. The model can be successfully used to predict costs, risks and service reliability, and to support asset management decisions when the model is implemented in an optimisation framework.

With the increase in human activity associated with the recent rise in Kuwait’s oil production, there is greater need for an optimised solution to protect the Kuwaiti coastline and islands from wave attacks and erosion. This thesis describes a programme of research conducted to support the development of a cost-effective method of protecting the Kuwaiti coastline with a breakwater system that also provides an opportunity to generate energy by locally increasing the energy density of waves to make wave energy conversion (WEC) more efficient, cost-effective and commercially competitive. A comprehensive review of the historical development and current state-of-the-art regarding breakwater and WEC technologies is presented. On the basis of these evaluations, a floating breakwater combined with point absorber device is identified as appropriate for use in the Kuwaiti near shore marine environment. The need for increasing the local energy density at the point absorber is highlighted and the concept of using a parabolic concentrator in combination with point absorber is suggested and developed. An analytical study extends the understanding of the role of damping in the response of an idealised point absorber device. A steady-state harmonic model is developed to simulate the motion of a single buoy with one degree of freedom (heave) along the vertical axis to optimise its geometrical and control parameters and maximise its power absorption from incident waves. Evaluating different buoy shapes namely: bullet, spike, and bi-cone (60o/120o) indicates that for each buoy shape, there is an optimum operating range for the power take-off (PTO) that drives the generator where wave energy capture and thus electrical power would be greatest. In the model, comprising a spring-damper system, the PTO is represented as a damper with a constant damping coefficient (〖 c〗_1) and the radiation force is represented by a linear radiation damping term (〖 c〗_2). The model reveals that the best performance is obtained at the optimum value for c_1 which is c_1= c_2=k/ω. This condition is met when the buoy with optimum mass is at resonance with the peak frequency of the sea state at ω^2=k/m. Evaluating the power absorption as a function of 〖 c〗_2 in the model also reveals that at resonance, a buoy of any shape will have two types of behaviour: one driven by low radiation damping and the other by high radiation damping range of values. Operation in the low 〖 c〗_2 region is difficult to achieve in practice, and hence, it is recommended that devices should be designed to operate in the high 〖 c〗_2 region to maximise power capture. Data is presented from wave tank testing conducted using a flume at the Kuwaiti Institute for Scientific Research (KISR). This is used to evaluate the capability of the proposed parabolic concentrator elements to increase potential wave energy harvesting. A wealth of data, both visualisation and numerical, was obtained and this compares well with the computational analyses. The results indicate that a parabola-buoy system would be capable of absorbing almost 260 kW of power at prototype scale (1:16). A computational modelling approach using the commercial CFD code ANSYS-Fluent is developed, applying the volume of fluid approach combined with a wave boundary condition. The KISR wave tank was modelled with parabolic element installed and data is compared to that obtained experimentally. Good agreement between CFD and experimental data is obtained validating the modelling choices made. Additional modelling results for the behaviour of waves near an anchored buoy in combination with a parabolic concentrator are presented. The work presented in this thesis shows that there is the potential for substantial benefit for power absorption through using a combined parabolic concentrator-point absorber device. Future modelling work with fluid-structure interaction and moving buoy will permit further optimisation and development paving the way for full-scale developments in the future.