The Offshore Installation Manager (OIM) performs one of the most complex and critical roles within the UK offshore oil and gas industry. The OIM is responsible for the safety and well-being of all persons onboard and within 500m of the installation whilst operating within an isolated and hostile physical environment within the UK Continental Shelf . The persistence of major incidents in the industry highlights the importance of OIM competence in controlling emergencies, consequently the research aims to contribute to new knowledge by identifying the potential barriers that can prevent the effective competence assessment of an OIM in this situation. The research utilised Engeström's Expanded Activity Theory to establish the holistic socio-cultural environment within which the OIM operates during emergency response to establish the key documents relevant to the role and associated competence assessment. The documents were then analysed using a critical hermeneutic approach based on the work of Phillips and Brown (1993) to determine the potential barriers to effective competence assessment of the OIM in controlling emergencies. The research is interdisciplinary and aims to develop new knowledge within the domains of safety engineering and law. The output from the research will assist industry Duty Holders improve the competence assessment of their appointed OIMs and allow safety engineers to consider the probable competence of an OIM at a given point in time. The research has identified 8 potential barriers to the effective competence assessment of OIMs in controlling emergencies. These are associated with the multiple definitions of competence that exist; the predominance of competence assessment by observation; the lack of definitive competence requirements for trainers and assessors; the complexity in UK legislation and the interaction between UK Government departments; concerns associated with goal setting legislation when applied to competence assessment and the lack of statutory competence requirements for OIMs in controlling emergencies; the lack of ownership of OIM competence and competence assessment; and the lack of regulation and independent audit of the competence assessment process of OIMs in controlling emergencies.

Made available in DSpace on 2014-06-12T17:39:12Z (GMT). No. of bitstreams: 2 arquivo6455_1.pdf: 3207032 bytes, checksum: 297d786de0f57e8107f170bb4300ad71 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O objetivo deste trabalho é apresentar uma metodologia simplificada baseada nos dados atualmente disponíveis, para demonstrar a estimativa preliminar de produção de energia eólica offshore no Brasil através de um estudo de caso com aplicação de aerogeradores. O Brasil possui cerca de 3,6 milhões de km² na sua Zona Econômica Exclusiva, área que pode ser aproveitada para a produção de energia eólica offshore. O estudo de caso foi realizado para a Ilha de Itamaracá no estado de Pernambuco com o intuito de suprir a demanda energética da Ilha, cujo consumo no ano de 2010 foi de 28.667 MWh. Realizou-se uma análise dos ventos no local através de um mapa eólico do oceano medido a 10 m de altura e com isso foi feita uma extrapolação da velocidade do vento para 90 m através da Lei Logarítmica. Calculou-se a distribuição de frequência de Weibull e a produção anual de energia. Analisou-se também a profundidade da água através da carta náutica para a definição de um local para aplicação dos aerogeradores. O resultado apresentado mostrou que três aerogeradores de 3 MW de potência à velocidade calculada de 7,15 m/s gerariam em torno de 30.000 MWh/ano, o que são suficientes para garantir energia durante todo o ano para a Ilha de Itamaracá

L’explosion de la plateforme de forage Deepwater Horizon qui s’est produite dans le Golfe du Mexique en 2010, à l’origine d’une catastrophe écologique sans précédent dans l’histoire des Etats-Unis, nous a conduit à nous interroger sur l’encadrement international de l’activité d’exploration et d’exploitation des hydrocarbures en mer et la protection de l’environnement. Parce que cette activité qui est exercée sur le plateau continental des états, génère des pollutions opérationnelles et accidentelles, et parce que la pollution marine ne connait pas les frontières, l’encadrement international d’une telle activité est de rigueur. L’activité qui a débuté à la fin du XIXe siècle a connu un véritable essor vers les années 70. A ce moment là, les états prennent conscience de la nécessité de protéger l’environnement. Dans le même temps, un régime international encadrant l’activité se développe entre les années 70 et les années 90. Se distingue alors le régime de prévention du régime de réaction. Dans un premier temps l’activité doit répondre à des exigences de prévention. Il n’existe toutefois pas un instrument universel exclusivement dédié à cette activité, de telle sorte que l’on observe un éclatement du régime au travers d’instruments directement applicables à vocation universelle et régionale, complétés par des instruments indirectement applicables relatifs à la protection de l’environnement. Malgré cet éclatement il en ressort que les principaux aspects constituant le cycle de vie de l’activité, partant de la délivrance de permis d’exploration et d’exploitation au démantèlement des plateformes en passant par le contrôle de l’activité sont relativement bien encadrés. Mais malgré cet encadrement nous ne sommes pas à l’abri de la survenance d’une pollution contre laquelle il faudra lutter.Dans ce second temps les états ont donc développé un régime de réaction en réponse aux pollutions opérationnelles et accidentelles. Concernant les pollutions opérationnelles, l’on voit en marge des régimes de prévention déjà existants et imposant certains seuils, se dessiner une lutte empirique contre ces pollutions, essentiellement à l’échelle régionale. Les états prennent conscience que les seuils de pollutions opérationnelles doivent être indéniablement plus contraignants. Concernant la lutte contre les pollutions accidentelles, les états disposent d’un régime international relativement satisfaisant puisqu’une série d’instruments prévoit les mesures imposées aux états que ces derniers doivent prendre en cas de survenance d’une pollution mais surtout parce qu’un instrument universel est dédié à cette problématique. L’existence d’un tel régime ne signifie par pour autant que les états doivent s’en contenter et doivent de cette manière en permanence faire évoluer le droit en vue d’un meilleur encadrement, telle qu’a su le faire l’Union européenne en adoptant en 2013 sa directive sur les accidents majeurs. / The deepwater Horizon oil rig explosion in 2010 in the Gulf of Mexico was the most important ecological catastrophe of the United States of America. This event inspired us to study the current international law about the hydrocarbon exploration and exploitation at sea and the protection of the environment. Because this activity takes place on the continental shelf it leads to operational and accidental pollutions, because marine pollution does not have frontiers, therefore legal international control of this activity is necessary.The activity which begun at the end of the nineteenth century, knew a real development around the 70's. At that moment, States became aware of the necessity to protect the environment. At the same time, an international settlement supervising the activity is emerging from the 70's to the 90's. Thus we can distinguish the prevention settlement from the react settlement. First of all the activity must respond to the prevention requirements. Notwithstanding, there is no universal treaty exclusively dedicated to this activity. That is why we do observe a splited settlement through universal and regional treaties directly applicable, completed by treaties indirectly applicable relating to environmental protection. Despite this splitting, we observe that principal aspects constituting the life cycle of the activity, from exploration and exploitation delivery permitted to decommissioning of paltforms, are well controled.Despite this control, a pollution can occur against which one we have to fight.That is why in the second time States developped a react settlement in response to the operational and accidental pollutions. About operational pollutions, we observe around the current preventional settelement which sets limits, developing some new limits through an empirical struggle, essentially at the regional level. States become aware that the limits imposed for operational pollution have to be more restrictive.With reference to the accidental pollutions, a current international settlement is quite satisfactory since various treaties and particularly an universal treaty, decree measures to States, which they fullfil if pollutions occure. This kind of instrument do not significate that States do not have to make the law progress. Indeed the law needs to evoluate permanentaly that is why UE adopted a directive about major accidents.At the same time react settlement not only means fighting pollution but also identifying the liable of the pollution and repare the damage, specifically the per se ecological damage.

The principal objective of this study was to investigate process simulation and optimization of an existing offshore natural gas process which needed profitability improvements. Optimization was done using two alternative approaches: a global approach (response surface methodology) or a local approach (successive quadratic programming). The global approach was characterized by process performance at selected case study points throughout the feasible operating region and made use of global information, while the local approach was characterized by numerical iterative computation driven by local information in the neighborhood of a single point in the design space. A Box-Behnken design was used as a second-order response surface design for the estimation of correlation between process simulator design variables and an economic objective function, and the estimation model was then optimized. In the local approach, a process simulator (ASPEN PLUS) with optimization capabilities was used. From the investigation, three major design variables were identified that had significant effects on the objective function of maximum product sales value. The three variables were: the compression ratio of the Production Compressor, the heat duty of the Gas/Gas Exchanger, and the compression ratio of the Expander. The results indicated that profitability of the offshore natural gas process could be improved by greatly (about 60%) increasing the production of raw condensate, even though this meant slightly lower (about 4%) sales of natural gas as a main product. The improvement found, however, was only 7% when the design variables were limited by currently installed equipment. The global approach was found to converge more consistently because once the global quadratic model was calculated, convergence to its unique optimum was simple. On the other hand the local approach had non-unique termination points due to the small effects of some design variables. The global approach provided better engineering insight since the effects of each design variable could be easily calculated from the quadratic model. However, the global approach was less efficient in terms of engineering manpower because of the time required to identify the quadratic model. / Graduation date: 1995

The construction of traditional large-scale central power plants and the extension of power lines in Taiwan have tremendous difficulties in terms of land acquisition and environmental protection for a long time. In addition, one potential risk of energy supply is that over 95% of energy source is imported overseas. Therefore, the most important goal of Taiwan energy policy is to cut down the amount of energy import. To achieve the goal, it is important to explore innovatively local energy source by developing renewable and clean energy. Around the available renewable energy technologies, wind power technique is the most mature one in addition to hydraulic power generation. However due to limited land resources and restrictive regulations, it is expected that wind farm development in Taiwan can only be located offshore, instead of inland. Besides, a multi-functional wind farm site, which involves ocean farm ranch, is desirable to bring mutual benefits for both developers and local stake holders. The current study has used System Dynamics(SD) to analyze the influence of Multi-functional offshore wind farm on economic. We discuss the change of fish catch with building offshore wind farm¡Aand the change of economic output in open ocean with offshore wind farm combine marine ranching. It is therefore easy for the decision makers to comprehend the economical benefit difference if an offshore multi-functional wind farm were to develop in the future. The result of this study is building offshore wind farm will reduced the fishing revenue in a short time¡Abut the total fishing revenue will increased in a long time. The Multi-functional offshore wind farm has better economic output than offshore wind farm.

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The lack of knowledge about the behaviour of footings for jack-up rigs under storm loads poses a design problem which can be tackled by model testing. The areas of prime concern are the ultimate loads on footings under combined loading, which affects the safety of the rig, and the rotational stiffness, which affects the interaction between the foundation and the structure. A programme of loading tests was performed on model footings on clay, and was divided into two stages: monotonic loading and cyclic loading. The clay samples were obtained by consolidating Speswhite kaolin slurry in cylindrical tanks 450mm in diameter. The strength and compressibility characteristics of the samples were verified by means of standard laboratory tests. The model footings were 50mm and 100mm in diameter and several shapes were tested: circular flat plate, cones of various angles and model spud-cans. Loads and displacements were monitored using appropriate instrumentation and a data logger. A series of central vertical loading tests provided data for comparison with existing bearing capacity theories. Combined loading tests were performed applying a displacement controlled horizontal load at a fixed height above the footing which was also subjected to a fixed vertical load. The main series of tests involved a parametric study of the relevant variables. Special tests allowed the assessment of the effect of embedment of the footing and the interaction of a flexible leg with the foundation. Cyclic loading tests were carried out using a load controlled system which applied a sinusoidal load simulating wave action. Effects of currents were investigated by introducing an offset to the loading cycle. The influence of amplitude and period of loading as well as the influence of vertical load were also investigated. Special tests were carried out to cover some peculiarities of real loading conditions. Fitting of a three-parameter hyperbola to the test results provided a systematic and accurate method of analysis of monotonic loading tests, leading to valuable information involving stiffness and ultimate loads. Analysis of cyclic loading tests yielded useful qualitative information regarding the progress of settlement and the variation of rotational stiffness and damping ratio with the number of cycles.

This thesis is a theoretical study, using both finite element and boundary element methods, of the behaviour of single-piles and pile groups under vertical and lateral loading. It offers an improved understanding of the soil-structure interaction that occurs in pile groups, particularly closely spaced piles subjected to lateral loads. The potential of a two- dimensional idealisation of what is a three-dimensional problem is demonstrated by achieving real insight into the complex nature of pile-soil and pile-soil-pile interaction in pile groups. A new load transfer mechanism is presented for a rigid, axially loaded vertical pile. From this an improvement is then derived to the analytical solution for pile head settlement given by Randolph and Wroth (1978). The improved mechanism has the further merit that it can be applied also to solutions for flexible piles and pile groups. The improved analytical solution is further adapted in the development of two correcting layers specifically for vertically loaded piles to model infinite boundaries in the finite element model. The correcting layers help in establishing superiority of the finite element method over the boundary element method. To model pile-soil interaction, a purely cohesive interface element is developed and then validated by performing various two-dimensional test problems, including stability analysis of flat surface footings. Footing-soil interface tension is successfully modelled in this way - an outcome that entails a significant modification to the Hansen (1970) bearing capacity solution. Stability analysis is also carried out of conical footings using a three-dimensional finite element model: the results help to explain the applicability of the existing bearing capacity theories to conical footings. The ultimate lateral soil reaction is determined and various pile loading stages are investigated through parametric studies. Study of the stage immediately following pile installation (i.e. the consolidation stage) highlights the need to develop an effective stress analysis for laterally loaded piles. Pile-soil interaction is studied using the cohesive interface element presented earlier, which proves to be quite successful in smoothing out the stress discontinuities around the pile. A new material model for frictional soils is presented, and validated by using it to model an extension test: it captures well post-peak behaviour and takes care of the effects of dilation on the response of laterally loaded piles. Finally, mechanisms of interaction in closely spaced pile groups are studied. Simple analytical expressions are derived which quantify the effects of interaction. A new method of analysis is presented for single-piles and pile groups which offers a considerable degree of reliability without having to do either impossibly expensive full scale field tests or prohibitively expensive full three-dimensional analysis using the currently available computers.

Offshore structures are used in a variety of applications ranging from the traditional oil and gas extraction facilities to emerging renewable energy concepts. These structures must be secured to the seabed in an efficient and cost effective manner. A novel approach is to use shallow inverted buckets as foundations, installed by suction, in place of the more usual piles. These foundations lead to cost savings through reduction in materials and in time required for installation. It is necessary to determine how these foundations perform under typical offshore loading conditions so that design calculations may be developed. This thesis presents experimental data from a comprehensive series of investigations aimed at determining the important mechanisms to consider in the design of these shallow foundations for dense sand. Initially the long term loading behaviour (e.g. wind and current) was investigated by conducting three degree of freedom loading {V:M/2R:H} tests on a foundation embedded in dry sand. The results were interpreted through existing work-hardening plasticity theories. The analysis of the data has suggested a number of improved modelling features. Cyclic and transient tests, representing wave loading, were carried out on a foundation embedded in an oil saturated sand. The novel feature of the cyclic loading was that a 'pseudo-random' load history (based on the 'NewWave' theory) was used to represent realistic loading paths. Of particular interest was the tensile load capacity of the foundation. The results observed suggested that for tensile loading serviceability requirements rather than capacity may govern design. Under combined-load cyclic conditions the results indicated that conventional plasticity theory would not provide a sufficient description of response. A new theory, termed 'continuous hyperplasticity' was used, reproducing the results with impressive accuracy. Surprisingly, under the conditions investigated, loading rate was found to have a negligible effect on response.

This thesis is concerned with four different types of offshore foundations, namely gravity foundations, jack-up foundations, the mudmats for piled jacket structures and caisson foundations for jacket structures. In most applications, these can be idealised as circular rigid foundations. Unlike onshore foundations, offshore foundations are subjected to large horizontal and moment loads. This research used the finite element method to examine the elastic behaviour and stability of circular footings under combined loading. Due to the circular shape of the footings and the combination of vertical, horizontal and moment loads, three dimensional finite element analysis was used. In-depth analyses of the elastic behaviour of circular footings under combined loading (V,H,M) were performed. The vertical stiffness coefficient was investigated using two dimensional axi-symmetric analyses whereas three dimensional analyses were used to examine the other coefficients. Different features of offshore foundations such as footing embedment and cone angle were taken into consideration. Based on the numerical results, a set of empirical expressions for elastic stiffness coefficient was derived. For footing stability calculations, large horizontal or moment loads can cause the footing to lose contact with the soil, or cause the footing to slide relative to the soil. In finite element analyses, this loss of contact and sliding are modelled by interface elements. A new zero-thickness iso-parametric interface element was formulated for both two and three dimensional analyses. An exact close formed solution for integration of the stress-strain relationship (for the two dimensional interface element) was found. The element is then used to explore footing stability. It was shown that by using a yield criteria which allows the interface to behave as either frictional or cohesive interface, depending upon the normal stress, numerical stability is achieved. The footing stability was examined by establishing the bearing capacity envelope. The envelopes for footings on undrained clays were established for surface flat strip footings and for surface flat circular footings. The effects of soil strength varying with depth, cone angle and embedment on the bearing capacity envelope were also investigated.