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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Valoração econômica da Gruta do Maquiné em Cordisburgo MG: uma aplicação do método do custo de viagem / Economic valuation of Maquine Cavern - Cordisburgo MG: an application of the travel cost method

Paula, Zélia Rodrigues de 15 February 2008 (has links)
Made available in DSpace on 2015-03-19T19:29:57Z (GMT). No. of bitstreams: 1 01 - capa_abstract.pdf: 104110 bytes, checksum: 9a26d488fd09651766208a527c72bc65 (MD5) Previous issue date: 2008-02-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Maquine Cavern is an important natural resource system located at Cordisburgo, in the state of Minas Gerais. It was built by nature in the last few thousand years and it is a significant source of knowledge to researchers and income to local people. Therefore, it is very important to preserve it. Visitors characteristics and econometric estimation of demand systems are key information which may be important to resource management decisions at local, state and federal levels. This study objective was to find the economic value of the Maquine Cavern. Specifically, the objectives were: a) To profile the Maquine Cavern visitor; b) To analyze the consumer surplus and the visitors response to variations in the admission fee by county; b) To analyze the consumer surplus and the visitors response to variations in the admission fee by consumer. The theory behind this study was the demand theory and public goods theory which support economic valuation methodologies to estimate natural resource prices . The analytical procedure was the Travel Cost method. Data were obtained by interviews (298) made with visitors in July 2007. Results showed that most visitors have high educational levels and generally do not travel alone and visit Maquine Cavern for the first time. Visitors which travel using their own cars show a high demand for visits and most visitors have monthly income between 2 and 5 minimum wages. The estimated Maquine Cavern average value with county data, i.e., the average willingness to pay for visits to the Maquine Cavern, revealed by visitors decisions in each county, was R$ 80.654,81. The average willingness to pay for visits to the Maquine Cavern, revealed by visitors when using individual data, was even smaller, R$ 12.688,32. The main conclusion was that estimated values do not show the real willingness to pay by individual for Maquine Cavern visits since the travel cost method did allow only the estimation of use values which represents a small part of total economic value of this natural resource. / A Gruta do Maquiné é um importante ativo ambiental do Município de Cordisburgo, no Estado de Minas Gerais. Formada ao longo de milhares de anos pela própria natureza, suas especificidades a colocam como fonte enriquecedora de conhecimento e também como fonte geradora de renda, fazendo-se, portanto, essencial a sua proteção. O conhecimento do perfil do visitante da Gruta do Maquiné e a estimativa da demanda de visitantes são informações que podem contribuir para melhor tomada de decisão dos gestores municipais, estaduais e nacional desse ativo. Dessa forma, o objetivo geral deste trabalho consistiu em determinar o valor econômico do ativo ambiental Gruta do Maquiné - MG. Especificamente pretendeu-se: a) traçar o perfil do turista da Gruta do Maquiné; b) analisar a resposta dos consumidores às variações na taxa de admissão da Gruta do Maquiné e o excedente do consumidor por município; c) analisar a resposta dos consumidores às variações na taxa de admissão da Gruta do Maquiné e o excedente do consumidor por indivíduo. A teoria que deu sustentação a este estudo foi a de demanda e a de bens públicos, que fornece o suporte necessário às metodologias de valoração econômica para a estimação dos preços dos ativos ambientais. O procedimento analítico usado foi o método do custo de viagem. Os dados foram obtidos por meio de questionários (298) aplicados aos visitantes da gruta no mês de julho de 2007. Os resultados obtidos demonstram que a maioria dos visitantes possui alto nível de escolaridade; em geral viajam acompanhados e visitam a gruta pela primeira vez. Observou-se ainda que os turistas que viajam em carro próprio apresentam demanda maior por visitas à Gruta do Maquiné e que a maior parcela de visitantes detém renda entre 2 e 5 salários mínimos. O valor médio estimado para a Gruta do Maquiné MG com dados agrupados por município, ou seja, a disposição total média a pagar por visitas à Gruta de Maquiné, revelada pelos visitantes de cada região, foi R$ 80.654,81. A disposição total média a pagar por visitas à Gruta, revelada pelos visitantes, quando avaliada por indivíduos foi ainda menor, R$ 12.688,32, comparativamente àquele valor obtido por município. Conclui- se, portanto, que os valores estimados não traduzem a real disposição dos indivíduos a pagarem por visitas à Gruta do Maquiné, visto que o método aplicado permitiu estimar somente o valor de uso direto do ativo, que representa apenas uma pequena parcela do valor econômico total deste ativo ambiental.
12

Rock cavern as thermal energy storage

Berglund, Simon January 2020 (has links)
In the fall of 2019, a comprehensive idea study was conducted on heat storage in two rock caverns located at Näsudden in Skelleftehamn and was part of the project course "Energiteknik, huvudkurs" at Luleå University of Technology. This idea study investigated the conditions of using waste heat from Boliden AB:s copper smeltery (Rönnskär) and storing this waste heat in two rock caverns and use them as seasonal thermal storage tanks, with the purpose of using the heat in the nearby district heating network, thus replacing some of the oil burned at Rönnskär. To investigate this, the authors of the idea study looked at two different storage cycles of seasonal storage and modeled this in ANSYS Fluent to simulate the heat storage and the heat losses. The results from this idea study showed promising results for using these caverns as heat storage and this work is therefore a continuation of the idea study. Since the study provided a good understanding of the conditions for seasonal storage, some questions arose about how the rock caverns will behave during an intermittent operation, which is the planned mode of operating the caverns in case of deployment. In this thesis, intermittent operation of these caverns are explored and how this effects the temperature in the caverns and its surrondings, the charge/discharge speed, how insulated walls affect the operation and how much oil is replaced. At the beginning of this project a review of the idea study and similar projects was done to gain deeper knowledge about the subject, but also to get a wider grasp on the different problems that could arise during the thesis. Relevant data for the caverns was collected and acquired to get a deeper understanding of its geometry, layout and what kind of modifications are really possible. Further data from the district heating networks of Boliden AB and Skellefteå Kraft was acquired. The available waste heat from Rönnskär was examined and used to calculate the chargeable energy by hour for the caverns, with the limits of Skelleftehamn district heating network in mind. By examining the different steam boiler patterns, the discharge pattern could be calculated. Using CFD, the unknown global heat transfer coefficient between the cavern water and the cavern wall can be determined. This data was then used with a set of differential equations to model the behavior of the caverns in Simulink. This allowed to determine the behavior for the caverns during normal operation, such as how the heat losses evolve, how the temperatures fluctuate, how much heat the caverns can be charged with and how much they can discharge. The results from the simulations showed that the caverns discharge a higher amount of energy when operating intermittently than when operating seasonally. Depending on how the caverns are utilized, different amounts of discharged energy are obtained. This range from 2224,7MWh to 7846,1MWh for the different discharging patterns. The usage also affects the efficiency of the cavern giving the efficiency a range between 19% to 53,9%. The heat losses range from around 20kW to 1000kW, depending on operation. Insulating the cavern walls reduces on average the heat losses by a factor of 5. Operating the caverns intermittently would on average remove a total of 29 ktonne CO2 and 88,74 tonne NOx for its expected lifespan of 30 years. Economically, the rock caverns have good economic potential as they would save about 80 million SEK during their lifetime just from buying less oil. / Hösten 2019 genomfördes en omfattande idéstudie om värmelagring i två bergrum vid Näsudden i Skelleftehamn och var en del av projektkursen "\textit {Energiteknik, huvudkurs}" vid Luleå tekniska universitet. Denna idéstudie undersökte villkoren för att använda spillvärme från Boliden AB:s kopparsmältverk (Rönnskär) och lagra denna värme i bergrummen och använda dem som säsongslagrade ackumulatortankar. Syftet med detta var att använda värmen i det närliggande fjärrvärmenätverket och därmed ersätta en del av den förbrända oljan hos Rönnskär. Författarna utforskade detta genom att undersöka två olika lagringscykler för säsongslagring och modellerade detta i ANSYS Fluent för att simulera värmelagring och värmeförluster. Resultaten från idéstudien visade lovande resultat för säsongsbaserad värmelagring i dessa bergrum och detta arbete är därför en fortsättning av idéstudien. Eftersom studien gav en god förståelse för förhållandena för säsongslagring, uppstod några frågor om hur bergrummen kommer att bete sig under en intermittent drift, vilket är den planerade driften av bergrummen vid en framtida användning. I detta projekt undersöks intermittent drift av dessa bergrum och hur detta påverkar temperaturen i bergrummen och dess omgivning, laddnings- / urladdningshastigheten, hur isolerade väggar påverkar driften och hur oljeförbrukningen reduceras. I början av detta projekt gjordes en genomgång av idéstudien och liknande projekt för att få djupare kunskap om ämnet, men också för att få ett bredare grepp om de olika problem som kan uppstå under arbetets gång. Relevant data för bergrummen samlades in och anskaffades för att få en djupare förståelse för dess geometri, layout och vilken typ av ändringar som verkligen är möjliga. Ytterligare data från fjärrvärmenätverket för Boliden AB och Skellefteå Kraft förvärvades. Den tillgängliga spillvärme från Rönnskär undersöktes och användes för att beräkna den urladdningsbara energin per timme för bergrummen, med begränsningarna i Skelleftehamns fjärrvärmenät i åtanke. Genom att undersöka de olika ångpannmönstren kan urladdningsmönstret beräknas. Med hjälp av CFD kan den okända globala värmeöverföringskoefficienten mellan bergrumsvattnet och bergväggen bestämmas. Denna data användes sedan med en uppsättning differentialekvationer för att modellera driften av bergrummen i Simulink. Detta gjorde det möjligt att bestämma beteendet för bergrummen under normal drift, till exempel hur värmeförlusterna utvecklas, hur temperaturen fluktuerar, hur mycket värme bergrummen kan laddas med och hur mycket de kan ladda ur. Resultaten från simuleringarna visade att bergrummen kan ladda ur en större mängd energi än vid en säsongsbetonad drift. Beroende på hur grottorna utnyttjas erhålls olika mängder urladdad energi. Detta sträcker sig från 2224,7MWh till 7846,1MWh för de olika urladdningsmönstren. Användningen påverkar också grottans effektivitet vilket ger en effektivitet mellan 19% och 53,9%. Värmeförlusterna sträcker sig från cirka 1000 kW till 20kw, beroende på drift. Isolering av bergväggarna minskar i genomsnitt värmeförlusten med en faktor 5. Att använda grottorna intermittent skulle i genomsnitt ersätta totalt 29 kton CO2 och 88,74 ton NOx för den förväntade livslängden på 30 år. Bergrummen har även god ekonomisk potential eftersom de skulle spara cirka 80 miljoner SEK under sin livstid bara från minskade oljekostnader.
13

Stakeholdermanagement aus Sicht des Markscheiders – Außenpolitik eines Bergbaubetriebes

Meyer, Stefan 02 February 2024 (has links)
Am Beispiel des Kavernenfeldes Epe, das mit seinen aktuell 76 Erdgaskavernen einen Anteil von 15% an den gesamtdeutschen Untergrundgasspeichern hat, soll gezeigt werden, wie das Markscheidewesen helfen kann, die „licence to operate“ bestehender Betriebe zu erhalten und den Genehmigungsprozess von Neuprojekten zu unterstützen. Bergbau ist nahezu immer mit Bodenbewegungen verbunden, der Betrieb von Salzkavernen zur Solegewinnung und Untergrundspeicherung macht hier keine Ausnahme. Naturgemäß ist das Interesse an den Auswirkungen der bereits eingetretenen sowie den noch zu erwartenden Bewegungen groß, sowohl bei Anwohnern wie auch den betroffenen Kommunen. In Epe helfen bei der Beantwortung dieser Fragestellungen die Erfahrungen aus 50 Jahren markscheiderischen Messungen an der Oberfläche (v.a. Nivellement, zunehmend auch GNSS/GPS und Radarinterferometrie) und im Untergrund (Hohlraumvermessungen der Kavernen). Neben den standortspezifischen Gegebenheiten wie Teufe und Salzgeologie ist bei Kavernen die Bedeutung der jeweiligen Nutzung entscheidend für das Senkungsgeschehen. Dabei liegt die größte Herausforderung in der mittel- bis langfristigen Antizipation des zukünftigen Kavernenbetriebs, da die Liberalisierung des Energiemarktes Mitte der 2000er Jahre zu einer sich mehr an betriebswirtschaftlichen Vorgaben orientierenden Fahrweise der Gasspeicher führte. Seitdem variiert die jährliche Konvergenz (Hohlraumverlust) der Gaskavernen stark, mit in der Folge ebenso veränderlichen Senkungsbeträgen an der Oberfläche. Die Annahme wahrscheinlicher Szenarien zum zukünftigen Betriebsgeschehen erlaubt trotz alledem verlässliche Senkungsprognosen, basierend auf dem etablierten analytischen Berechnungsmodell nach Sroka/Schober. Informationen zu verschiedenen Messmethoden (neben den markscheiderischen sind hier z.B. Beobachtungen des Grundwasserspiegels zu nennen), ihrer Ergebnisse und deren Bewertung sowie die Präsentation der Senkungsprognosen erfolgten in Epe bei mehreren Öffentlichkeitsterminen in den vergangenen Jahren. Essentiell war dabei der Rückgriff auf markscheiderisches Wissen, um die Informationen korrekt und verständlich zu transportieren. Bei mittlerweile fast 1 m Senkung im Kavernenfeld Epe und sich neu anbahnenden Nutzungskonzepten wie Wasserstoff- und Druckluftspeicherung ist eine erfolgreiche Kommunikation elementar, um ein gegenseitiges Vertrauen und Verständnis für unternehmerische Ziele einerseits sowie den Sorgen der Bevölkerung andererseits zu entwickeln. Im Folgenden soll das Senkungs- und Umweltmonitoring im Kavernenfeld Epe im Detail vorgestellt werden, ergänzt um die Erfahrungen in der Vermittlung dieser Ergebnisse.
14

AA-CAES physical modelling: integration of a 1D TES code and plant performance analysis

Santo, Luca January 2018 (has links)
The focus of this thesis work was the development of an approachto couple a previosly existing Thermal Energy Storage (TES) modelwritten in C++ with a Simulink/Simscape plant model to simulate anAdvanced Adiabatic Compressed Air Energy Storage (AA-CAES) plant.After the creation and validation of such tool, the complete modelwas used to run simulations, with the aim of assessing the AA-CAESplant's performance under multiple patterns of charge anddischarge.Most of the works found in the literature only provide values ofstorage efficiency obtained from analytical approaches, whilethose that use simulation tools provide average values ofefficiencies when the plant is performing a series of identicalcycles of charge and discharge. During this thesis project,instead, simulations were performed for consecutive irregularcycles determined as the plant response to the electric grid powerrequest. The average efficiency values obtained provide thereforea better representation of how the plant would perform in realapplications.The results show that, under the assumptions made, the AA-CAESplant's overall storage efficiency is influenced very weakly byalterations of the charge-discharge patterns, and that goodperformances can be expected not only for identical chargedischargeconsucutive cycles, but for any pattern that observesthe cavern pressure limits, as long as the thermal energy storageis sized wisely.In addition, a sensitivity analysis was performed in order toassess the influence of turbomachinery efficiency on overallstorage efficiency, for a specified plant layout. The results showthat the turbine efficiency is the most affecting parameter to theplant's performance, while the impact of the main compressors'sinefficiency is mitigated by the thermal recovery that takes placein the TES.The present work confirms that AA-CAES is a promising technologyand that storage efficiencies above 70% can be achieved even inrealistic production scenarios.Finally, future steps for more accurate simulations of plants'performances and more detailed energy production scenarios areproposed.MSc ET 18007Examinator: Joakim WidénÄmnesgranskare: Ane HåkanssonHandledare:
15

Konvertering av oljelager till värmelager : I Sundsvalls fjärrvärmesystem / Conversion of oil storage to thermal energy storage

Hagstedt, Love January 2020 (has links)
This study has examined how an oil storage could be converted into a thermal heat storage (TES). Focus was put on the transient thermal heat flow that occurs during the early years when using a rock cavern as a TES. First existing literature were studied to learn from earlier experiences. Crucial steps of a conversion were identified as well as important mistakes that have been made in the past. Simulations of Sundsvall’s district heating (DH) system were made to see what impact a large TES would have. These simulations showed the importance of being able to transfer enough amount of heat. Then heat simulations were preformed to study the transient heat flow. This showed that much of the heat will be heating the rock around the cavern. Over time, the losses decrease as the rock around the cavern remains heated, due to its thermal inertia. This means that some energy needs to be considered an investment cost as it will not be used in the DH-grid but will increase the efficiency of the TES. 4 different heating strategies were analysed and the heat losses during 25 years were measured. The results showed that a conversion would save between 0,7 – 1,55 million SEK annually depending on how many caverns were converted and cost approximately 6 million SEK for one cavern, 10,5 million SEK for two caverns and 15 million SEK for three caverns. / I denna studie har det undersökts hur ett oljelager kan omvandlas till ett termisk värmelager. Fokus låg på det transienta värmeflödet som inträffar under de första åren när ett bergrum används som värmelager. Först studerades litteratur för att lära av tidigare erfarenheter. Avgörande steg för en konvertering identifierades liksom viktiga misstag som har gjorts tidigare. Simuleringar av Sundsvalls fjärrvärmesystem gjordes för att se vilken påverkan ett stort värmelager skulle ha. Dessa simuleringar visade vikten av att kunna överföra tillräcklig mängd värme. Därefter genomfördes värmesimuleringar för att studera det transienta värmeflödet. Detta visade att mycket av värmen kommer att värma berget runt bergrummet. Med tiden minskar förlusterna när berget runt rummet förblir uppvärmd på grund av dess termiska tröghet. Detta innebär att en del energi måste betraktas som en investeringskostnad eftersom den inte kommer att användas i fjärrvärmesystemet utan kommer att öka effektiviteten hos lagret. Fyra olika uppvärmningsstrategier analyserades och värmeförlusterna under 25 år mättes. Resultaten visade att en omvandling skulle spara mellan 0,7 - 1,55 miljoner SEK årligen med en trivial driftstrategi beroende på hur många bergrum som konverterades och kosta cirka 6 miljoner SEK för ett bergrum, 10,5 miljoner SEK för två bergrum och 15 miljoner SEK för tre bergrum. I framtida studier bör en optimal driftstrategi tas fram utifrån det aktuella systemet.
16

Untersuchungen zur Bohrungsintegrität sowie dem Gasverhalten von Wasserstoff in Salzkavernen unter Berücksichtigung variabler Randbedingungen

Kirch, Martin 19 May 2023 (has links)
Salzkavernen gelten als vielversprechende Möglichkeit Wasserstoff unter Tage zu speichern. Da aktuell keine Salzkaverne zur kommerziellen Wasserstoffspeicherung in Deutschland existiert, wurden Forschungsvorhaben initiiert, um offene Fragen in diesem Bereich zu klären. Die vorliegende Arbeit beschäftigt sich mit der Bestimmung der Dichtheit eines ausgewählten technischen Bohrungsbarriereelements: der letzten zementierten Rohrtour. Laborative Permeabilitätsmessungen stellen eine Möglichkeit dar, den Nachweis der Dichtheit zu erbringen. Zur Messung der Permeabilität werden zwei Versuchsanlagen gebaut, die auf einem instationären Messprinzip basieren. Mit Hilfe dieser Anlagen wird die Durchlässigkeit von Einzelmaterialproben und Verbundproben bestehend aus Steinsalz, Anhydrit, Zementstein und Futterrohr bestimmt und bewertet. Zur Auswertung der Versuche wird eine Software programmiert, die die eindimensionale Strömungsgleichung mit Hilfe der Finiten-Volumen-Methode numerisch löst. Die Arbeit beschreibt die weltweiten Erfahrungen im Bereich untertägiger Wasserstoffspeicherung. Weiterhin wird der Stand der Technik von Permeabilitätsmessungen dargestellt und die Eigenschaften des verwendeten Messverfahrens beschrieben. Mit Hilfe der Auswertung von Dichtheitstest kann gezeigt werden, dass die Anlagen zum Nachweis niedrigster Permeabilitäten geeignet sind. Das grundliegende mathematische Modell und dessen numerische Approximation wird hergeleitet. Die numerischen Fehler und der Modellfehler werden mit Hilfe einer Genauigkeitsanalyse bestimmt. Über die Analyse der Messunsicherheiten der Eingangsparameter erfolgt eine Abschätzung der Messunsicherheit der berechneten Permeabilität. Die Ergebnisse der Permeabilitätsmessungen zeigen, dass der untersuchte Zementstein dichte Verbunde mit Steinsalz und Futterrohr gegenüber Wasserstoff ausbilden kann. Als wichtigste Einflussgröße auf die Permeabilität wird der Effektivdruck identifiziert. Ein Einfluss der Messgase (Wasserstoff und Methan) auf das Strömungsverhalten kann, mit Ausnahme des Klinkenberg-Effekts, nicht nachgewiesen werden. Erfahrungen aus dem Bereich der Erdgasspeicherung sind prinzipiell auf die Wasserstoffspeicherung übertragbar. Die Ergebnisse der Untersuchungen sind in die Erstellung eines Leitfadens zur Errichtung von Wasserstoffkavernen für Genehmigungsbehörden und zukünftige Investoren eingeflossen.
17

[pt] GEOMECÂNICA DE ROCHAS SALINAS APLICADA A PROJETOS ESTRATÉGICOS DE ENGENHARIA / [en] SALT GEOMECHANICS APPLIED TO STRATEGIC ENGINEERING PROJECTS

PEDRO ALCIDES LOBO PENNA FIRME 20 June 2022 (has links)
[pt] A importância do sal em diversas atividades humanas tem acompanhado as fases principais da civilização. Aplicações estratégicas e inovadoras envolvendo rochas salinas são planejadas até os dias atuais, tais como barreiras geológicas para abandono de poços e cavernas de estocagem para novas fontes de energia ou descarbonização. Esta tese foca no comportamento geomecânico do sal com atenção especial à fluência, dilatância, efeitos térmicos e seus impactos no comportamento hidráulico. Modelos deram suporte ao desenvolvimento de metodologias para avaliação de condições de integridade e estanqueidade de projetos estratégicos no contexto de energia. Eles incluem o abandono de poços do pré-sal, cavernas de sal e sal como rocha capeadora de reservatórios carbonáticos. Simulações numéricas avançadas utilizando o framework GeMA investigaram cenários representativos de cada projeto. Para tanto, modelos constitutivos de fluência, condições de contorno customizadas e variáveis de saída específicas foram implementados. Dentre os modelos de fluência, o EDMT foi desenvolvido no contexto desta pesquisa de doutorado, com foco no sal brasileiro. Os estudos de caso conduziram a observações importantes. Um poço do pré-sal pode fechar completamente por fluência após a remoção do revestimento. A redução da pressão e o aquecimento do poço aceleraram seu fechamento de modo significativo. No cenário mais crítico, a permeabilidade final foi ligeiramente superior a 100 vezes o valor inicial. Uma caverna de sal pode suportar mecanicamente ciclos de pressão causados por um esquema contingencial de fornecimento de hidrocarbonetos, embora uma permeabilidade final de 6,5 vezes o valor inicial tenha sido observada. Na geomecânica de reservatórios, a contribuição da fluência da rocha capeadora na subsidência é pequena e irreversível mesmo que a pressão do reservatório seja recuperada. As mudanças na permeabilidade foram sutis apesar da contribuição da fluência do sal e da variação de pressão do reservatório. A revisão da literatura, os modelos de fluência, as metodologias de análise, as funcionalidades incorporadas ao framework e as discussões motivadas pelos estudos de caso representam o valor agregado da tese para a comunidade científica e para a indústria no que tange ao aproveitamento estratégico de rochas salinas. / [en] The importance of salt in many human activities has accompanied the main phases of civilization. Strategic and innovative applications in salt rocks are planned until the present day, such as geological barriers for well abandonment and storage caverns for new energy sources or decarbonization. This thesis focuses on the geomechanical behavior of salt with special regards to creep, dilation, thermal effects and their impact on the hydraulic behavior. Models have supported the development of methodologies to assess integrity and tightness conditions of strategic projects in the context of energy. These include Pre-salt well abandonment, salt caverns and salt as caprock of carbonate reservoirs. Advanced numerical simulations using the framework GeMA have investigated representative scenarios of each project. To this end, creep constitutive models, customized boundary conditions and specific output variables have been implemented. Among the creep models, the EDMT has been developed in the context of this doctoral research, focusing on Brazilian salt. The case studies have led to important findings. A Pre-salt well can close completely by creep after casing removal. Pressure reduction and well heating have accelerated closure significantly. In the most critical scenario, the final permeability was slightly higher than 100 times the initial value. A salt cavern can mechanically support pressure cycles caused by a contingency hydrocarbon supply scheme; however, a final permeability of 6.5 times the initial value has been noticed. In reservoir geomechanics, the caprock creep contribution in the subsidence is small and irreversible even if the reservoir pressure is recovered. Permeability changes have been subtle despite the creep contribution and the reservoir pressure variation. The literature review, the creep models, the analysis methodologies, the capabilities incorporated into the framework and the discussions motivated by the case studies represent the added value of the thesis to the scientific community and industry regarding the strategic use of salt rocks.
18

Posouzení výhodnosti výstavby přečerpávací vodní elektrárny velkého výkonu v lokalitě Cukrová bouda, okres Šumperk / The assessment of advantages of construction of large hydroelectric power plants in the area of Cukrova bouda, district Sumperk

Knápek, Michal January 2012 (has links)
The subject matter of the master´s thesis is, in particular, an evaluation of the advantageousness of the construction of a pumped-storage hydroelectric power station in the vicinity of Cukrová Bouda. In the master´s thesis introduction the utilisation of pumped-storage hydroelectric power stations in providing reserve power generation to the operator of a power transmission system is discussed. The thesis then focuses on a technical design solution where two alternatives are drawn up for which the nominal parameters of individual designs for a pumped-storage hydroelectric power station are specified. The following part deals with the impact of the structure and the plant’s subsequent operation on the environment. A further key part is the determination of investment and subsequent operating costs and an evaluation of the plant according to economic pointers. The final part of the master´s thesis contains a SWOT analysis and an assumed programme of works for the plant’s preparation and actual construction. The conclusion contains an overall evaluation.
19

[pt] EFEITO DA FLUÊNCIA DO SAL NO CRESCIMENTO DE PRESSÃO EM ANULAR CONFINADO DE POÇOS DE PRÉ-SAL / [en] SALT CREEP EFFECT ON THE ANNULAR PRESSURE BUILD UP IN SUBSALT WELLS

HERNAN EDUARDO EISENHARDT PEREZ 01 February 2016 (has links)
[pt] Este trabalho apresenta o crescimento de pressão no anular causado pela fluência do sal e relaciona com o cálculo deste fenômeno quanto ao efeito térmico, que é normalmente conhecido por APB (annular pressure build-up). Este fenômeno não é modelado em softwares comerciais e deve ser considerado em poços de pré-sal. O cálculo de APB considera três mecanismos geradores de pressão no anular: expansão térmica do fluido do anular, expansão do tubing e influxo e efluxo do fluido confinado no anular. Mudanças no volume do anular, causados pela fluência do sal, podem ser tratadas como um quarto mecanismo, equivalente ao influxo de fluido no cálculo do APB. O cálculo deste fenômeno pode ser incorporado a um modelo de cálculo acoplado ( multistring casing design ) através da programação do APB causado pelo efeito de expansão térmica dos fluidos confinados e o APB causado pela fluência do sal. Para isso é necessário adotar um modelo constitutivo para descrever o comportamento de fluência desta rocha em função do estado de tensão, perfil de temperatura, tipo de sal, tempo decorrido, energia de ativação e outros fatores. Os efeitos de APB devido à fluência do sal podem ser mais pronunciados quando a sapata do revestimento é assentada em um intervalo de sal com elevado gradiente de sobrecarga e elevado gradiente geotérmico. Não considerar o efeito da fluência do sal no crescimento de pressão do anular (APB) pode causar um dimensionamento inadequado de revestimento ou packoff e levar a perda da integridade do poço. / [en] This paper presents the annular pressure build-up caused by salt creep and link to current calculation of this phenomenon due to thermal effect, which is commonly known as APB. This phenomenon is not currently modeled on commercial software and should be considered in subsalt wells. The calculation of APB considers three generator mechanisms: thermal expansion of annular fluid, influx or efflux and tubing buckling. Changes in the annular volume, caused by salt creep, may be treated as a fourth mechanism, equivalent to the influx in current calculation of APB. The calculation of this phenomenon can be incorporated into a multistring casing design model by programming the thermal expansion effect and the APB caused by salt creep. This requires adopting a constitutive model to describe the creep behavior of rock for differential stress, temperature profile, salt type, salt thermal activation and other factors. When the casing shoe is seated in deep salt sections with high overburden gradient and high temperature from the produced hydrocarbons, effects of APB due to salt creep and thermal effects may be more pronounced. Not considering the salt creep effect in the annular pressure build-up (APB) can lead to inadequate casing design and possible loss of well integrity.

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