Dissertations / Theses on the topic 'Oil wells – Hydraulic fracturing'
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King, Jeremy Scott. "Acoustical signal during hydraulic fracturing." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=565.
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Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains x, 82 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references (p. 42).
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CACHAY, LEONARDO RODIN SALAS. "PROPPANT FLOWBACK IN OIL WELLS STIMULATED BY HYDRAULIC FRACTURING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=6513@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROUm dos principais objetivos da engenharia de petróleo é desenvolver e aplicar técnicas capazes de aumentar a produtividade de poços de petróleo, incluindo a estimulação da formação através de operações que aumentem a permeabilidade da rocha-reservatório e facilitem o escoamento do fluido. Dentre as técnicas de estimulação, a mais utilizada é o fraturamento hidráulico, a qual tem viabilizado a exploração em cerca de 40% dos poços produtores de petróleo em todo o mundo. Durante o fraturamento hidráulico, um material granular conhecido como material de sustentação ou propante, é injetado nas fraturas recém-criadas com o objetivo de mantê-las abertas e garantir-lhes condições de alta permeabilidade. A produção de material de sustentação (proppant flowback) é termo usado para descrever o refluxo do propante para o interior do poço, juntamente com o hidrocarboneto produzido. O controle do fluxo de propante representa um grave desafio para a indústria de petróleo, pois pode causar graves problemas operacionais e de segurança, relacionados com o desgaste dos equipamentos de produção, problemas econômicos associados ao custo de limpeza, paralisação das operações e intervenção no tratamento da fratura, problemas ambientais relacionados com a disposição de sólidos impregnados por hidrocarbonetos, etc. Neste contexto, a presente dissertação apresenta um estudo detalhado dos principais tipos de propante e de suas propriedades, bem como descreve os mecanismos que influem no refluxo do material de sustentação da fratura e analisa os principais modelos apresentados na literatura para previsão deste fenômeno. Uma retroanálise considerando os dados de campo em 22 poços da Petrobrás, localizados em Sergipe, permite uma comparação da eficiência entre quatro dos modelos, desenvolvidos com base em resultados de ensaios de laboratório, indicando suas vantagens e desvantagens para aplicação na prática da engenharia.
One of the main objectives of petroleum engineering is to develop and to apply techniques aiming the productivity increase of oil fields, including the stimulation of the rock through operations that increase the permeability of the oil reservoir and makes the flow of the fluid toward the well more efficient. Among the stimulation techniques, the most used is the hydraulic fracturing, carried out in about 40 percent of the producing oil wells around the world. During hydraulic fracturing, a granular material known as proppant, is injected into the just created fractures with the objective to keep them open and in order to guarantee the designed conditions of high permeability. Proppant flowback is the technical terminology employed to describe the flow of proppant from the fracture to the interior of the oil well, together with the produced hydrocarbon. An efficient and reliable control of this problem is still a major challenge to the oil industry, given the serious operational and security problems that it may cause, including costs of interrupted operations, cleaning measures, environmental contamination risks associated with the disposal of residues impregnated by oil, etc. In this context, the present thesis presents a detailed description on the main proppant materials and their engineering properties and available treatments, as well as on the physical mechanisms that control the flowback phenomenon. Several simple models published in the literature, that permit the forecast of proppant flowback in a fast and easy way, are also presented and discussed. Finally, a back-analysis considering the actual conditions in 22 Petrobras oil wells located in Sergipe was also carried out, what permitted a comparison among the results calculated according 4 prediction models, putting in evidence their advantages, shortcomings and adequacy as a design or control tool in the design and exploration of oil fields stimulated by hydraulic fracturing.
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Valencia, Karen Joy Petroleum Engineering Faculty of Engineering UNSW. "Optimising hydraulic fracture treatments in reservoirs under complex conditions." Awarded by:University of New South Wales. School of Petroleum Engineering, 2005. http://handle.unsw.edu.au/1959.4/23318.
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Growing global energy demand has prompted the exploitation of non-conventional resources such as Coal Bed Methane (CBM) and conventional resources such as gas-condensate reservoirs. Exploitation of these resources primarily depends on stimulation by hydraulic fracturing. Traditional hydraulic fracturing practices, however, are in many ways inadequate in addressing difficulties associated with these non-conventional and conventional resources. For example, complex in-situ stress distribution, large material property contrasts and unique production mechanism complicate the implementation of hydraulic fracture treatments in CBM and gas-condensate reservoirs respectively. An integrated approach to optimise hydraulic fracture treatments in reservoirs under complex conditions is developed in this thesis. The optimisation methodology integrates a fracture geometry model which predicts fracture geometry for a given set of treatment parameters, a production model which estimates reservoir productivity after stimulation and an economic model which calculates net present value. A stochastic optimisation algorithm combining features of evolutionary computations is used to search for the optimum design. Numerical techniques such as finite element analysis, iterative semi-analytical methods and evolutionary computation are also used. The following are the major contributions of this thesis: 1. A three-dimensional hydraulic fracture geometry model which accounts for poroelastic effects, in-situ stress and rock material properties, has been developed to provide a more realistic description of the hydraulic fracture geometry. This served as a tool to visualise hydraulic fracture propagation for a given in-situ stress distribution, rock material properties and treatment parameters. Furthermore, by accounting for poroelastic effects, it is possible to identify the causes of exceptionally high treatment pressures. 2. An innovative production model was formulated in this thesis to quantify the well deliverability due to hydraulic fracturing. The production model has been used for a range of production scenarios for CBM and gas-condensate reservoirs such as: multiple wells at arbitrary locations and various well types (stimulated and unstimulated wells). 3. The optimisation methodology presented in this work provides a platform for operators to assess risks and gains associated with different field development scenarios. The added feature of sub-optimal NPV contouring provided flexibility to calibrate the treatment design in real-time. The strength of the optimisation methodology lies in the flexibility to: (1) impose design constraints, (2) optimise multiple variables and (3) simulate multiple objectives.
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Echavarria, Erika. "Acoustic properties of a 2-D fracture during formation." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=1143.
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Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains xiii, 132 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 98).
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VELOZO, LILIANE TOJEIRA. "STUDY OF PROPPED MATERIAL OF FRACTURES STIMULATED BY HYDRAULIC FRACTURING IN OIL WELLS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2006. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8725@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOA viabilidade da exploração de um campo petrolífero está associada às características produtivas da formação, obtidas mediante o desenvolvimento e a aplicação de técnicas capazes de aumentar a economicidade dos poços. A técnica de estimulação mais utilizada atualmente é o fraturamento hidráulico, que tem como uma das etapas principais a injeção de um material granular, denominado de propante, para a manutenção da abertura da fratura. Tal técnica tem como obstáculo o refluxo do propante para o interior do poço (proppant flowback), ocasionando diversos problemas que podem levar à interrupção da produção do mesmo. Alguns modelos teóricos e empíricos foram desenvolvidos para a previsão desse fenômeno, mas os mecanismos que o governam não são ainda claramente explicados. Alguns fatores que influenciam na produção de propante são largura da fratura, tensão de fechamento, gradiente hidráulico e características do propante. O refluxo de propante não é considerado nos procedimentos atuais de projeto de fraturamento hidráulico. Nessa dissertação de mestrado foi desenvolvida uma ferramenta computacional com uma arquitetura orientada a objeto, em linguagem de programação Java, para a análise de estabilidade do propante no interior da fratura com base em modelos empíricos e teóricos. Além disso, foi investigada a influência da inclusão de restrições no projeto de fraturamento de modo a prevenir o fenômeno. Busca-se, desse modo, a obtenção de melhores projetos de fraturamento hidráulicos com prevenção do refluxo de propante, garantindo a produtividade do poço e prolongando sua vida útil.
The viability of the exploration of an oil field is associated with the productive characteristics of the formation, guaranteed by means of the development and application of techniques capable of increasing the productivity and the economy of the oil fields. The currently most used stimulation technique is hydraulic fracturing, by which one of the main stages is the injection of a granular material called proppant to keep the fracture open and enhance fracture permeability. This technique presents as a drawback the phenomenon known as proppant flowback. The proppant is carried to the inside of the well causing many problems which can lead to production interruption. Some empirical and theoretical models for its prediction have been developed, however the mechanisms that govern it are still not clearly explained. Parameters that are related to proppant flowback are fracture width, closure pressure, drag force and proppant characteristics. Proppant flowback prediction is not included in today s procedures of the hydraulic fracturing project. In the present work a computational tool for proppant stability analysis was developed based on empirical and theoretical prediction models. This tool has an object oriented architecture written in Java language. The influence of the introduction of restrictions to prevent proppant production in the hydraulic fracture design procedure was also investigated. In this way, it is aimed to obtain hydraulic fracturing projects by which proppant flowback is prevented in field situations assuring well productivity and extending its activity period.
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Yin, Qingqing. "Transporting and Disposing of Wastewater from North Dakota Oil Producers." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26541.
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North Dakota?s oil boom is aided by a new technology, fracking. But this technology implies large amounts of wastewater. The methods of dealing with this wastewater are now an issue. Currently, North Dakota locks it into deep injection wells in the Bakken formation. With the development of membrane technologies to treat wastewater, it may be feasible to treat the wastewater and reuse it.
This study uses a mathematical programming model to minimize the total cost of dealing with wastewater using three methods - deep well injection, on-site treatment, and off-site treatment. The model results show it is cost-effective to use on-site and large capacity off-site treatment to treat the 20% of the wastewater that flows back within the first 30-60 days after a well is drilled.
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Dohde, Farhan A. "Estimation of Air Emissions During Production Phase from Active Oil and Gas Wells in the Barnett Shale Basin: 2010-2013." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc799523/.
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The Barnett shale basin, the largest onshore gas field in the state of Texas, mainly produces natural gas. The basin’s oil and gas productions have dramatically increased over the past two decades with the enhancement via shale fracturing (fracking) technology. However, recent studies suggest that air emissions from shale fracking have significantly contributed to the growing air pollution problem in North Texas. In this study, air emissions from the Barnett shale basin during the production phase of the oil and gas activities (once the product is collected from the wells) are quantified. Oil and gas production data were acquired from the Texas Railroad Commission for the baseline years of 2010 through 2013. Methodology from prior studies on shale basins approved by the Texas Commission on Environmental Quality was employed in this study and the emission inventories from the production phase sources were quantified. Accordingly, the counties with the most gas operations in the basin, Tarrant, Johnson, Denton and Wise, were found to be the highest emitters of air pollutants. Tarrant County was responsible for the highest emitted NOx (42,566 tons) and CO (17,698 tons) in the basin, while Montague County released the maximum VOC emissions (87,601 tons) during the study period. Amongst the concerned emitted pollutants, VOC was the largest emitted pollutant during the study period (417,804 tons), followed by NOx (126,691 tons) and CO (47,884 tons). Significant Sources of air emissions include: storage tanks, wellhead compressor engines, and pneumatic devices. Storage tanks and pneumatic devices contributed to about 62% and 28% of the total VOC emissions, respectively. Whereas, wellhead compressor engines are primarily responsible for about 97% of the total NOx emissions. Finally, in Tarrant, Wise and Denton counties, the emissions increased during the study period due to increase in the oil and gas production, while Johnson County’s emission contribution declined throughout the study period.
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Neumann, Luís Fernando. "Investigação experimental sobre a geração, visualização e avaliação da condutividade de fraturas ácidas em carbonatos microbiais." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265384.
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Orientadores: Jose Luiz Antunes de Oliveira e Sousa, Paulo Dore FernandesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências
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Resumo: O sucesso da estimulação por fraturamento hidráulico ou ácido é dependente da geração de condutividade. No fraturamento hidráulico sustentado, a condutividade é gerada pela introdução de uma quantidade significativa de um agente de sustentação granular e praticamente esférico. No fraturamento ácido, a condutividade é gerada por irregularidades reveladas devido à reação desigual do ácido em cada uma das faces da fratura naturalmente rugosa e da resistência destas mesmas irregularidades para suportar as tensões que atuam após o fechamento da fratura. A baixa resistência das irregularidades leva ao colapso e cicatrização da fratura ácida com a perda total da condutividade. Esta dissertação investiga a viabilidade da estimulação por fraturamento ácido em carbonatos microbiais rasos e profundos. Ensaios de laboratório em escala reduzida foram projetados para verificar se a condutividade de uma fratura induzida por reação química da rocha reservatório com um ácido forte pode ser mantida frente às elevadas tensões normais efetivas que agirão na fase de explotação do poço. A dissertação ainda investiga se o emprego de uma pequena quantidade de agente de sustentação é capaz de dividir os esforços aplicados sobre as irregularidades de uma fratura ácida e manter a condutividade por maiores períodos de tempo. As superfícies que imitam fraturas ácidas são criadas pelo ataque ácido em corpos de prova em condições de laboratório que reproduzem em escala aquelas observadas em um fraturamento ácido real. Imagens digitais são utilizadas para medir a rugosidade das fraturas ácidas e o consumo de rocha carbonática pelo ácido na face do corpo de prova. A resistência das irregularidades é medida indiretamente pelo decréscimo da condutividade da fratura ácida frente a tensões de confinamento crescentes. O efeito ou não da adição de agente de sustentação é medido pela comparação dos parâmetros da correlação empírica desenvolvida por Nierode e Kruk
Abstract: A well succeeded stimulation by hydraulic or acid fracturing is related to conductivity creation. In a hydraulic fracturing, the conductivity is created by means of introducing a significant amount of a propping agent. In an acid fracturing, the conductivity is related to the creation of asperities due to uneven acid reaction on each naturally rougher fracture side and the asperities strength to withstand high stresses that start to act just after fracture closure. Low asperities strength leads to collapse of acid fracture and fracture healing with total conductivity loss. The dissertation investigates the feasibility of acid fracturing stimulation in shallow and deep microbial carbonates. Laboratory tests were designed to verify if the acid fracture conductivity induced by chemical reaction of reservoir rock with a strong acid could be kept when facing the high effective normal stress that is expected in exploitation phase. The dissertation still investigates whether the use of a small amount of proppant is able to share the tension that acts on asperities and maintain the acid facture conductivity for longer periods. The surfaces that mimic acid fractures are created by acid etching specimens in laboratory conditions reduced in scale from those observed in an actual acid fracturing job. Digital images are used to measure fracture roughness and rock consumption by acid on the specimen face. The asperities strength is indirectly measured from acid conductivity decrease under increased confinement tension. The effect of adding or not adding propping agent is accomplished comparing empirical parameters from Nierode and Kruk correlation
Mestrado
Explotação
Mestre em Ciências e Engenharia de Petróleo
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Cleto, Pedro Rogério. "Simulação de fraturamento hidráulico usando elementos finitos de elevada razão de aspecto com acoplamento hidromecânico /." Bauru, 2016. http://hdl.handle.net/11449/140148.
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Orientador: Osvaldo Luís ManzoliBanca: Flavia de Oliveira Lima Falcão
Banca: Leonardo José do Nascimento Guimarães
Resumo: A técnica de fraturamento hidráulico é amplamente utilizada na indústria petrolífera para aumentar a permeabilidade da rocha-reservatório numa região próxima ao poço e permitir a extração, e consequente produção, de hidrocarbonetos armazenados em seus poros. Primeiramente a rocha é perfurada criando-se um poço e então injeta-se fluido a uma pressão suficientemente alta para fraturar a rocha. A injeção contínua de fluido permite que as fraturas se propaguem pelo reservatório, formando assim canais de alta permeabilidade. A modelagem e simulação computacional de fraturamento hidráulico são complexas em função da física envolvida no processo. O presente trabalho objetiva o estudo da formação e propagação de fraturas induzidas hidraulicamente em meios rochosos de baixa permeabilidade e também tem o propósito de verificar se a metodologia adotada é capaz de reproduzir características apresentadas num processo de fraturamento hidráulico, como a pressão necessária para causar a ruptura da rocha. Para tal, apresenta-se a técnica de fragmentação da malha utilizando elementos finitos de elevada razão de aspecto (ou elementos de interface) para representar a fratura, aos quais são atribuídas relações constitutivas baseadas na mecânica do dano. Além disso, os elementos de interface também possuem um acoplamento hidromecânico capaz de representar o canal de alta permeabilidade devido à ocorrência da fratura. Os resultados obtidos mostraram que os elementos de interface asso... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The hydraulic fracturing technique is widely used to increase the permeability of reservoirs in the vicinity of the well and to allow the extraction and subsequent production of hydrocarbons trapped in its pores. Firstly, the rock is drilled, creating a well and then a fluid is injected at a sufficiently high pressure to fracture the rock. The continuous fluid injection allows the fractures to propagate through the reservoir, thereby forming some high permeability paths. The computer modeling and simulation of hydraulic fracturing are complex due to the physics involved in the process. This work aims to study the formation and propagation of hydraulically induced fractures in rocky media with low permeability and also aims to verify if the adopted methodology is able to reproduce the characteristics presented in a hydraulic fracturing process, as for instance, the required pressure to cause the breakdown of the rock. For this purpose, it is presented the mesh fragmentation technique using finite elements with a high aspect ratio (or interface elements) to represent the fracture, which are assigned constitutive relations based on damage mechanics. Besides, the interface elements also have a hydromechanical coupling which is able to represent the high permeability path due to the fracture. The results showed that the interface elements associated with the mesh fragmentation technique were able to represent both the formation and the propagation of hydraulically induc... (Complete abstract click electronic access below)
Mestre
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Damas, Renato Gomes. "Avaliação da qualidade dos modelos de fraturamento hidraulico." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258703.
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Orientadores: Philippe Remy Bernard Devloo, Sonia Maria GomesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Neste trabalho avalia-se três modelos que retratam o processo de fraturamento hidráulico. O primeiro, desenvolvido por Fernandes [1998], trata-se de um modelo semi- nalítico cuja formulação fundamenta-se na taxa constante de injeção de fluido fraturante. Esse modelo apresenta como vantagem a simplicidade dos cálculos e a obtenção imediata dos resultados, por outro lado tem seu campo de atuação limitado a intervalos específicos de eficiência volumétrica para os quais foi elaborado. Os outros dois são modelos numéricos desenvolvidos por Devloo et al. [2001] e Devloo [2001]. Incorporam em seu equacionamento taxa variável de injeção e por efetuarem cálculos iterativos são independentes quanto a eficiência volumétrica do processo. Os resultados dos modelos numéricos foram comparados com os do modelo semi-analítico. Buscando-se, desta forma, validar os modelos numéricos para o uso em simulações de fraturamento hidráulico, principalmente para as condições de injeção de água presentes em poços com alta porosidade. Pretende-se com isso oferecer maior liberdade e flexibilidade durante o planejamento da operação de fraturamento. Oferecendo ao projetista a possibilidade de adoção de taxa injeção variável, períodos sem injeção intercalados com períodos com injeção, liberdade para utilização de diferentes fluidos fraturantes entre outros benefícios.
Abstract: The purpose of this research has been evaluated three models of hidraulic fracturing. The first one, developed byFernandes [1998], is a semi-analytical model whose formulation is based on a constant rate of injection of fracturing fluid. This model presents as advantage the simplicity of the calculations and the immediate attainment of the results, on the other hand its performance is limited at specific intervals of volumetric efficiency for which it was elaborated. The others two are numerical models developed by Devloo et al. [2001] and Devloo [2001]. They incorporate variable injection rate and due to the iterative calculations they are not limited in a range of volumetric efficiency of the process. The results of the numerical models had been compared with the ones of the semianalytical model. Searching, in such a way, to validate the numerical models for the use in simulation of hydraulic fracturing, mainly for the characteristic conditions of water injection present in wells with high porosity. It is intended with this to provide freedom and flexibility during the planning of the operation of fracturing. Offering to the designer the possibility to use variable injection rate, periods without injection intercalated with periods with injection, freedom to choose differents fracturing fluids among others benefits.
Mestrado
Estruturas
Mestre em Engenharia Civil
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Romanó, James Luigi. "Modelo numérico para determinação de zonas de perda de circulação de fluido de perfuração em poços de petróleo." Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2631.
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Durante a perfuração de poços de petróleo, a determinação do perfil de temperaturas no poço é importante para tomada de decisões relativas ao processo de cimentação, para a seleção de revestimento do poço e equipamentos e, sobretudo, na identificação de zonas de influxo e perda de circulação. Neste trabalho é proposto um modelo matemático da transferência de calor em regime transitório do escoamento de fluido de perfuração em poços fraturados com perda de circulação. O poço é representado de maneira simplificada através de um cilindro anular concêntrico, cuja parede externa (interface poço-formação) apresenta uma ou mais fraturas discretas. Para a obtenção do modelo térmico é realizado um balanço de energia com foco nas trocas de calor entre a coluna de perfuração, região anular e formação rochosa. A característica principal do modelo proposto é a possibilidade de detecção da posição e número de fraturas a partir do perfil do gradiente térmico da região anular ao longo poço. Para tanto, com o código numérico, obtido via método dos volumes finitos, investiga-se a influência de parâmetros: da fratura (profundidade relativa, perda de circulação, número e distância entre fraturas), físicos (tempo de circulação) e do regime de escoamento (número de Reynolds e viscosidade dos fluidos de perfuração). As variáveis-resposta principais analisadas são a temperatura da região anular e o gradiente térmico. Como variáveis-resposta secundárias são utilizadas as evoluções térmicas da temperatura no fundo do poço e na saída da região anular. É constatado que o aumento da profundidade relativa ou número de fraturas diminui a temperatura do fundo do poço, sem causar variação significativa na temperatura de saída do anular. Para a variação da perda de circulação, o efeito na temperatura do fundo do poço é similar ao da variação do aumento da profundidade relativa da fratura, no entanto são observadas diferenças na temperatura de saída. Além disso, é verificado que, conforme se aumenta o número de fraturas distribuídas ao longo da profundidade do poço, a temperatura do poço tende ao caso de poço não fraturado. De maneira similar é evidenciada a tendência de que a diminuição na distância entre fraturas se aproxima dos resultados para um poço com uma única fratura. Finalmente, o aumento da perda de circulação facilita a detecção de fraturas devido a respectiva mudança na descontinuidade do perfil do gradiente térmico da região anular.During oil drilling operations, the wellbore temperature profile is used when selecting well casing materials, making cementation related decisions, and, most importantly, to identify loss zones. In this work, a transient heat transfer mathematical model for a fractured wellbore is proposed. The well has its geometry simplified to a concentric annular cylinder which has one or more discrete fracture in its external wall (wellformation interface). In order to obtain the thermal model an energy balance is used, focusing the heat transfer between the pipe, the annular region and the formation. The key characteristic of the model is the fracture detection through thermal gradient graphical analysis. The thermal gradient is an output of the solution of the discretized energy equation in the domains, obtained through the finite volume method. The following parameters are investigated: fracture depth, fracture number, fracture interference, loss circulation, circulation time, Reynolds number and drilling fluid viscosity. The analysis is done through the analysis of the annular region temperature profile and its gradient, along with the thermal evolution of both the bottomhole and outlet temperatures. It is verified that increasing the fracture relative depth or number decreases the bottomhole temperature, while having no significant impact in the outlet temperature. The same bottomhole temperature effect is noted when increasing loss rate, however outlet temperature changes are observed. In a similar way, when decreasing the distance between fractures, the temperature profile in the annular region trends to a wellbore with a single fracture. Finally, increasing loss rate favors fracture detection, since the discontinuity in the annular region thermal gradient profile is intensified.
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Wang, Wenxin. "Methodologies and new user interfaces to optimize hydraulic fracturing design and evaluate fracturing performance for gas wells." Texas A&M University, 2005. http://hdl.handle.net/1969.1/3268.
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This thesis presents and develops efficient and effective methodologies for optimal
hydraulic fracture design and fracture performance evaluation. These methods
incorporate algorithms that simultaneously optimize all of the treatment parameters while
accounting for required constraints. Damage effects, such as closure stress, gel damage
and non-Darcy flow, are also considered in the optimal design and evaluation algorithms.
Two user-friendly program modules, which are active server page (ASP) based, were
developed to implement the utility of the methodologies. Case analysis was executed to
demonstrate the workflow of the two modules. Finally, to validate the results from the
two modules, results were compared to those from a 3D simulation program.
The main contributions of this work are:
An optimal fracture design methodology called unified fracture design (UFD)
is presented and damage effects are considered in the optimal design
calculation.
As a by-product of UFD, a fracture evaluation methodology is proposed to
conduct well stimulation performance evaluation. The approach is based on
calculating and comparing the actual dimensionless productivity index of
fractured wells with the benchmark which has been developed for optimized
production.
To implement the fracture design and evaluation methods, two web ASP
based user interfaces were developed; one is called Frac Design (Screening),
and the other is Frac Evaluation. Both modules are built to hold the following
features.
o Friendly web ASP based user interface o Minimum user input
o Proppant type and mesh size selection
o Damage effects consideration options
o Convenient on-line help.
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Asif, Ehsan Syed Mortuza. "Three Essays on the Economics of Hydraulic Fracturing." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/72130.
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Hydraulic fracturing has been increasingly used in the USA to economically extract natural
gas and oil from newly discovered shale plays. Despite new, more severe, and long term
impacts of hydraulic fracturing compared to conventional drilling, regulatory practices are
mostly implemented by states that regulate with older regulations that were were written
before the widespread use of hydraulic fracturing. This dissertation presents three essays on
the economics of hydraulic fracturing. A standard renewable lease in hydraulic fracturing
runs for a five-year primary term. The first essay examines the effect of initial contract length
on extraction behavior and social costs. It finds that the rate of extraction decreases over
time for both, the social planner and the private extractor. In addition, the social planner
has a more stable extraction path compared to the private extractor. Holding other things
equal, if the social planner seeks to induce a private extractor to leave a higher in situ stock
un-extracted, then the optimal contract duration is longer. Simulations illustrate the magnitude
of social costs inherent in hydraulic fracturing and non-optimal fixed contract lengths. The second essay investigates the impact of the significantly increased bonding requirements
for horizontal wells introduced in West Virginia in December, 2011, on the probability of
violation committed by those wells. Results suggest that the increased bonding requirement
has reduced the probability of violation by 2.6 to 3.2 percentage points. Moreover, it slightly
reduces the number of violations done by horizontal wells. Finally, the third essay explores
several aspects of Act-13, introduced on February 14, 2012, by Pennsylvania. This act imposes new fees that are assessed annually for fifteen years, on all unconventional gas wells in Pennsylvania. This chapter explores the impacts of Act-13 on the likelihood of an unconventional well's shut-down, rate of extraction, and probability of violation. Results suggest that wells incurring this increased fee schedule have a significantly higher likelihood (more than three times) of shut-down. Also, Act-13 have reduced the extraction rate, and the probability of violation committed by unconventional wells in Pennsylvania.Ph. D.
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Ma, Long. "Interpretation of sequential hydraulic tests /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Lopez, Hernandez Henry De Jesus. "Optimal fracture treatment design for dry gas wells maximizes well performance in the presence of non-Darcy flow effects." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1103.
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This thesis presents a methodology based on Proppant Number approach for optimal fracture treatment design of natural gas wells considering non-Darcy flow effects in the design process. Closure stress is taken into account, by default, because it is the first factor decreasing propped pack permeability at in-situ conditions. Gel damage was also considered in order to evaluate the impact of incorporating more damaging factors on ultimate well performance and optimal geometry. Effective fracture permeability and optimal fracture geometry are calculated through an iterative process. This approach was implemented in a spreadsheet.
Non-Darcy flow is described by the β factor. All β factor correlations available in the literature were evaluated. It is recommended to use the correlation developed specifically for the given type of proppant and mesh size, if available. Otherwise, the Pursell et al. or the Martins et al. equations are recommended as across the board reliable correlations for predicting non-Darcy flow effects in the propped pack.
The proposed methodology was implemented in the design of 11 fracture treatments of 3 natural tight gas wells in South Texas. Results show that optimal fracture design might increase expected production in 9.64 MMscf with respect to design that assumes Darcy flow through the propped pack. The basic finding is that for a given amount of proppant shorter and wider fractures compensate the non-Darcy and/or gel damage effect.
Dynamic programming technique was implemented in design of multistage fractures for one of the wells under study for maximizing total gas production. Results show it is a powerful and simple technique for this application. It is recommended to expand its use in multistage fracture designs.
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Aydin, Adnan. "Interpretation of well tests in acute fracture-wellbore systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1994. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25766.pdf.
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Uzunian, Adrian B. "Interpreting Risk: Variations and Explanations of Resident Perceptions of Hydraulic Fracturing Impacts." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/4745.
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Hydraulic fracturing is a novel technological development that has pushed the extraction of energy resources forward. As technology improves and world oil and gas markets shift, more shale formations are being uncovered, and new drilling activities are seen as economically viable. I examine the ways in which residents perceive environmental and health risks of hydraulic fracturing in the Eagle Ford Shale region of Texas, and how these perceptions differ depending on social position and where the resident is receiving their information. To understand how residents perceive the environmental and health risks associated with the Eagle Ford Shale oil and gas boom, or if these perceptions differ by social status and information sources, I conducted a qualitative analysis of key informant and focus group interview data, coding for major themes found in interview transcripts. I found that groups in lower social positions had increased concern regarding environmental and health risk perceptions than those in higher social positions. Additionally, respondents in lower social positions discussed all environmental and health risk perceptions with a relatively higher breadth and depth than those in higher social positions. Regarding information sources, those in higher social positions tend to receive more of their information on hydraulic fracturing from government officials and industry. Those in lower social positions receive more information from interpersonal networks, although they generally discussed a general lack of information concerning oil and gas development. These findings contribute to a relatively small field of growing research on resident perceptions in a hydraulic fracturing context. This research also brings attention to rural populations who are being uniquely impacted by hydraulic fracturing and provides insight into a region, the Eagle Ford Shale, where there is a need for more scholarly research.
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Leap, Shannon J. "Roots Versus Wells: Grassroots Activism Against Fracking in New York and California." Scholarship @ Claremont, 2015. http://scholarship.claremont.edu/pitzer_theses/64.
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The reliance upon and depletion of fossil fuels as an energy source puts pressure on individuals, communities, energy companies, and policy-makers. Hydraulic fracturing – known colloquially as fracking – as a method of drilling for oil and natural gas temporarily alleviates this pressure since it allows for the extraction previously inaccessible fossil fuels in shale rock deposits deep beneath the Earth’s surface. This has resulted in a nationwide “fracking boom,” which has come with its share of economic benefits. However, the process of fracking can be detrimental to human and environmental health. In reaction to the increasing development of this practice, many communities across the country are mobilizing against fracking. This thesis will focus on the grassroots activism against fracking in New York, where fracking was banned in December 2014, and in California, which is largely slated as the next frontier for the expansion of fracking and thus battleground for the fight against fracking. Using grassroots academic literature, media coverage of fracking and activism in each state, and interviews from organizers working in each state, this thesis will examine the motivations, frameworks, strategies, and tactics used in each grassroots campaign in order to offer lessons in successes and opportunities for improvement within these anti-fracking efforts and others across the country.
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Fuchs, Grace Frances. "How Community Concerns about Hydraulic Fracturing and Injection Wells can be Addressed Through the Application of Environmental Monitoring Technology." Ohio University Honors Tutorial College / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1556136264849063.
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Solis, Alyssa M. "The Political Landscape of Hydraulic Fracturing: Methods of Community Response in Central Arkansas." Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/pitzer_theses/42.
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This thesis looks at the current fracking debate on a national scale, before focusing specifically on how this debate is playing out in the landscape of Central Arkansas. Focusing on the lack of national regulation, the unique array of state regulations that have popped up are assessed in their effectiveness on the ground through speaking with residents of the area. The demographics of these residents are analyzed within an assessment of environmental injustice vulnerability. This ethnographic approach also compares the de jure v. de facto outcomes of these regulations through the narratives of residents working with organizations across the political spectrum, and specifically seeks to gauge their own personal stories and experiences with regulators and the fracking industry. Other key actors are identified. This thesis concludes that agency capture is a reality for these residents, and their perceived powerlessness drastically increases the power of the gas companies that monopolize the political agenda in the region.
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Whalen, Christina. "The Environmental, Social, and Economic Impacts of Hydraulic Fracturing, Horizontal Drilling, and Acidization in California." Scholarship @ Claremont, 2014. http://scholarship.claremont.edu/cmc_theses/969.
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The oil extraction mechanisms of hydraulic fracturing, horizontal drilling, and acidization have recently spread throughout the state of California. This thesis explores and assesses whether federal and state legislation should approve of fracking operations in California after studying its effects on human health, the environment, and the economy. This thesis assesses the impacts of fracking; analyzes the role of current legislation and regulation; compares California fracking to fracking in other states and countries; and provides recommendations for future action.
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Botner, Elizabeth. "Elevated methane levels from biogenic coalbed gas in Ohio drinking water wells near shale gas extraction." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439295392.
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Evans, Morgan Volker. "Microbial transformations of organic chemicals in produced fluid from hydraulically fractured natural-gas wells." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555609276432456.
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Salzman-Gubbay, Gideon J. "Earth, Air, Water, Oil: Regulating Fracking in the Monterey Shale with Health and Environment in Mind." Scholarship @ Claremont, 2014. http://scholarship.claremont.edu/pomona_theses/112.
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“Earth, Air, Water, Oil: Regulating Fracking in the Monterey Shale with Health and Environment in Mind,” explores how hydraulic fracturing regulation in California’s oil-rich Monterey Shale will impact regional public health, including groundwater and air quality. This is achieved through a combination of case study and policy analysis on both the state and national level.
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Warren, Alisa Renee Warren. "The Monster on the Hill: A Story of Environmental Injustice in Appalachia." Ohio University Honors Tutorial College / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1524840984220302.
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Reilly, Darren A. "Identification of Local Ground Water Pollution in Northeastern Pennsylvania: Marcellus Flow-back or Not?" Kent State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1397949957.
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Sakinejad, Michael Cyrus. "The Landscape Legacies of Gas Drilling in North Texas." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849745/.
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In North Texas, the Barnett Shale underlies large areas of the Dallas-Fort Worth Metroplex (DFW), which magnifies debates about the externalities of shale gas development (SGD). Continued demand for natural gas and expansive urbanization in DFW will cause more people to come in contact with drilling rigs, gas transport, and other urban shale gas landscapes. Thousands of gas wells within the DFW region occupy a large, yet scattered land surface area. DFW city planners, elected officials, and other stakeholders must deal with current and future urban growth and the surface impacts that are associated with gas development. This research examines how shale gas landscapes affect urban land uses, landscapes, and patterns of development in DFW. The study focuses on multiple fast growing DFW municipalities that also have high numbers of gas well pad sites. This study asks what are the spatial characteristics of gas well production sites in DFW and how do these sites vary across the region; how do gas well production sites affect urban growth and development; and how are city governments and surface developers responding to gas well production sites, and what are the dominant themes of contestation arising around gas well production sites and suburban growth?
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Clarkberg, Jasper W. "Regulatory Uncertainty and the Natural Gas Industry in the US." Oberlin College Honors Theses / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1495560884199246.
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Roshankhah, Shahrzad. "Physical properties of geomaterials with relevance to thermal energy geo-systems." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54893.
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Energy related geo-systems involve a wide range of engineering solutions from energy piles to energy geo-storage facilities and waste repositories (CO₂, nuclear). The analysis and design of these systems require proper understanding of geo-materials, their properties and their response to extreme temperature and high stress excitations, the implications of mixed-fluid conditions when contrasting fluid viscosities and densities are involved, the effect of static and cyclic coupled hydro-thermo-chemo-mechanical excitations, and rate effects on the response of long design-life facilities.
This study places emphasis on thermal geo-systems and associated physical properties. Uncemented soils and rocks are considered. The research approach involves data compilation, experimental studies and analytical methods. Emphasis is also placed to engineer geomaterials in order to attain enhanced performance in energy geo-systems. The thermal conductivity and stiffness of most geomaterials decrease as temperature increases but increase with effective stress. This macroscale response is intimately related to contact-scale conduction and deformation processes at interparticle contacts. Pore-filling liquids play a critical role in heat conduction as liquids provide efficient conduction paths that can diminish the effects of thermal contact resistance. Conversely, grains and fluids can be selected to attain very low thermal conductivity in order to create mechanically sound thermal barriers. In the case of rock masses, heat (and gas) recovery can be enhanced by injecting fluids at high pressure to cause hydraulic fractures. Scaled experiments reveal the physical meaning of hydraulic fractures in pre-structured rocks (e.g., shale) and highlight the extensive self-propped dilational distortion the medium experiences. This result explains the higher production rate from shale gas and fractured geothermal reservoirs that is observed in the field, contrary to theoretical predictions.
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Hensley, Colton Dwayne. "Maximal Proposition, Environmental Melodrama, and the Rhetoric of Local Movements: A Study of The Anti-Fracking Movement in Denton, Texas." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062840/.
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The environmental problems associated with the boom in hydraulic fracturing or "fracking," such as anthropogenic earthquakes and groundwater contamination, have motivated some citizens living in affected areas such as Denton, Texas to form movements with the goal of imposing greater regulation on the industry. As responses to an environmental threat that is localized and yet mobile, these anti-fracking movements must construct rhetorical appeals with complicated relationships to place. In this thesis, I examine the anti-fracking movement in Denton, Texas in a series of three rhetorical analyses. In the first, I compared fracking bans used by Frack Free Denton and State College, Pennsylvania to distinguish the argumentative claims that are dependent on the politics of place, and affect strategies localities must use in resisting natural gas extraction. In the second, I compare campaign strategies that use local identity as a way of invoking legitimacy, which reinforces narrative frameworks of environmental risk. In the third, I conduct and analyze interviews with anti-fracking leaders who described the narrative of their movement, which highlighted tensions in the rhetorical construction of a movement as local. Altogether, this thesis traces the rhetorical conception of place across the rhetoric of the anti-fracking movement in Denton, Texas, while seeking to demonstrate the value of combining rhetorical criticism with rhetorical field methods.
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Gorman, Mary Kathleen. "Social Consequence, Stakeholder Influence, and Resource Needs for Marcellus Shale Communities." ScholarWorks, 2014. https://scholarworks.waldenu.edu/dissertations/103.
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The process of natural gas recovery by horizontal drilling and hydraulic fracturing, known as fracking, is a major scientific advance in unconventional energy development. Attention has largely been focused on its economic advantages and potential negative environmental repercussions, while less consideration given to its social dimensions. The purpose of this study was to explore the social consequences of fracking for communities in the Appalachian Basin's Marcellus shale. Research questions focused on the role of stakeholders and the resource needs of localities in shaping public policy. This study was guided by the tenets of the Boomtown theory along with key issues in fracking research such as environmental impacts, water resources, public health and safety, economics, and ethical concerns. An embedded case study research design was employed, using a purposive sample of 8 economic and policy subject matter experts from the 3 most prolific drilling counties in Pennsylvania. Data were collected by semi-structured interviews and were analyzed using open and axial coding with cross-case comparison. Results suggested that positive economic social consequences of fracking involved sustainability in providing generational and employment stability. Negative consequences, such as traffic, damaged infrastructure, and housing shortages, were temporary and manageable. Logistical and demographic information were valuable resources for community leadership, and stakeholders favored autonomy in decision making. The implications for social change include informing policy makers how to prepare the local workforce to be adaptable, establish sufficient infrastructure to support change, and educate communities to leverage opportunity in advance of new industry.
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Ahmadi, Mahdi. "Ozone Pollution of Shale Gas Activities in North Texas." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849624/.
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The effect of shale gas activities on ground-level ozone pollution in the Dallas-Fort Worth area is studied in detail here. Ozone is a highly reactive species with harmful effects on human and environment. Shale gas development, or fracking, involves activities such as hydraulic fracturing, drilling, fluid mixing, and trucks idling that are sources of nitrogen oxides (NOX) and volatile organic compounds (VOC), two of the most important precursors of ozone. In this study two independent approaches have been applied in evaluating the influences on ozone concentrations. In the first approach, the influence of meteorology were removed from ozone time series through the application of Kolmogorov-Zurbenko low-pass filter, logarithmic transformation, and subsequent multi-linear regression. Ozone measurement data were acquired from Texas Commission on Environmental Quality (TCEQ) monitoring stations for 14 years. The comparison between ozone trends in non-shale gas region and shale gas region shows increasing ozone trends at the monitoring stations in close proximity to the Barnett Shale activities. In the second approach, the CAMx photochemical model was used to assess the sensitivity of ozone to the NOX and VOC sources associated with shale oil and gas activities. Brute force method was applied on Barnett Shale and Haynesville Shale emission sources to generate four hypothetical scenarios. Ozone sensitivity analysis was performed for a future year of 2018 and it was based on the photochemical simulation that TCEQ had developed for demonstrating ozone attainment under the State Implementation Plan (SIP). Results showed various level of ozone impact at different locations within the DFW region attributed to area and point sources of emissions in the shale region. Maximum ozone impact due to shale gas activities is expected to be in the order of several parts per billion, while lower impacts on design values were predicted. The results from the photochemical modeling can be used for health impact assessment and air quality management purposes. Both studies in this research show that the impact of shale gas development on local and regional level of ozone is significant, and therefore, it should be considered in the implementation of effective air quality strategies.
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Schlothmann, Daniel. "Kurz- und langfristige Angebotskurven für Rohöl und die Konsequenzen für den Markt." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-201396.
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In dieser Arbeit wurden Angebotskurven für 22 bedeutende Ölförderländer ermittelt und anschließend zu globalen Angebotskurven aggregiert. Gemäß den ermittelten Angebotskurven sind nahezu alle gegenwärtig in der Förderphase befindlichen Ölprojekte in den Untersuchungsländern auch beim aktuellen Ölpreis von 35 bis 40 US-$ je Barrel unter Berücksichtigung der kurzfristigen Grenzkosten rentabel. Sollte der Ölpreis jedoch in den kommenden Jahren auf diesem Niveau verharren, wird es bis zum Jahr 2024 zu einem Angebotsengpass auf dem globalen Ölmarkt kommen, da zur Deckung der zukünftigen Nachfrage die Erschließung kostenintensiver, unkonventioneller Lagerstätten und von Lagerstätten in tiefen und sehr tiefen Gewässern notwendig ist. Damit es bis zum Jahr 2024 nicht zu einem solchen Angebotsengpass kommt, ist gemäß des ermittelten langfristigen Marktgleichgewichts ein Ölpreis von mindestens 80 (2014er) US-$ je Barrel notwendig.
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Blattler, Stephanie. "A regulação diante de incertezas científicas: um estudo sobre a possibilidade de exploração e produção de shale gas no Brasil." reponame:Repositório Institucional do FGV, 2018. http://hdl.handle.net/10438/20591.
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In Brazil, the debate regarding the exploration and production of shale gas became relevant with the 12th Bid Round promoted by the National Oil, Natural Gas and Biofuels Agency (ANP), which offered areas with great potential of such unconventional hydrocarbon. The country is listed as the tenth with greater shale gas potential in the world. However, due to the international controversy involving this energy source, mainly by virtue of its potential environmental impacts and damages, the matter was brought to the courts and is subject to legislative initiatives, so that the production of such hydrocarbon in Brazil has not started yet. Therefore, the present essay aims to clarify how the exploration and production of shale gas takes place and what would be its potential harmful effects to the environment, demonstrating that there are diverging scientific opinions over the most relevant of such effects. The description of the existing regulatory instruments in Brazil, such as ANP Resolution No. 21/2014, is also provided herein, as well as the description of the current legal proceedings and bills over the matter. Following, this essay also describes how the shale gas matter was solved in four states/countries, as to verify if there are any valuable lessons for Brazil. Based on the scientific uncertainty over the potential environmental damages and impacts, the precautionary rule is herein analyzed, aiming to understand how precaution may be applied to shale gas and to other cases under similar scientific uncertainty. Initially, the doctrine of absolute precaution is presented, followed by the main critics to precaution. Finally, the main conclusion is that the path of interpretation for the shale gas case and for other cases with similar scientific uncertainty is the use of the precautionary rule modulated by proportionality, so that its application does not reflect an immediate prohibition, but the management of uncertainties through regulation.
No Brasil, a discussão a respeito da exploração e produção de gás de folhelho, conhecido de forma equivocada como “gás de xisto”, ganhou expressividade com a 12ª Rodada de Licitações promovida pela Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP), que licitou áreas com grande potencial exploratório para esse hidrocarboneto não convencional. O país apresenta o décimo maior potencial de gás de folhelho do mundo, porém, em razão da polêmica internacional que envolve essa fonte energética, principalmente em função de seus potenciais impactos e danos ambientais, a questão permanece judicializada e objeto de iniciativas legislativas, de forma que a produção desse hidrocarboneto no Brasil ainda não foi iniciada. Nesse âmbito, o presente trabalho visa esclarecer como se dá a exploração e produção do gás de folhelho e quais seriam seus potenciais efeitos nocivos ao meio ambiente, demonstrando a divergência existente na comunidade científica sobre os mais relevantes desses potenciais efeitos. O trabalho também traz a descrição dos instrumentos regulatórios já existentes sobre o gás de folhelho no Brasil, como a Resolução ANP nº 21/2014, bem como dos processos judiciais e projetos de leis existentes sobre a questão. Em seguida, o presente trabalho também descreve como a questão do shale gas foi decidida em quatro estados/países, para verificar se podem ser extraídas lições para o Brasil. Com base na incerteza científica constatada sobre os potenciais danos e impactos ambientais, o postulado da precaução é aqui analisado, visando compreender como ele pode ser aplicado ao caso do gás de folhelho e a outros casos de incerteza científica análoga. Inicialmente, é apresentada a doutrina da precaução absoluta, para posteriormente introduzir as principais críticas ao postulado. Por fim, conclui-se que o caminho para a interpretação do caso do gás de folhelho e de outros casos em que recai incerteza científica análoga é a utilização do postulado da precaução modulado pela proporcionalidade, de modo que sua aplicação não reflita uma proibição imediata, mas sim o gerenciamento das incertezas envolvidas por meio da regulação.
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Liu, Yajun. "Settling and hydrodynamic retardation of proppants in hydraulic fractures." Thesis, 2006. http://hdl.handle.net/2152/2766.
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Aghighi, Mohammad Ali Petroleum Engineering Faculty of Engineering UNSW. "Fully coupled fluid flow and geomechanics in the study of hydraulic fracturing and post-fracture production." 2007. http://handle.unsw.edu.au/1959.4/40621.
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This work addresses the poroelastic effect on the processes involved in hydraulic fracturing and post-fracture production using a finite element based fully coupled poroelastic model which includes a triple system of wellbore-fracture-reservoir. A novel numerical procedure for modeling hydraulic fracture propagation in a poroelastic medium is introduced. The model directly takes into account the interaction of wellbore, hydraulic fracture and reservoir in a fully coupled manner. This allows realistic simulation of near fracture phenomena such as back stress and leak-off. In addition, fluid leak-off is numerically modeled based on the concept of fluid flow in porous media using a new technique for evaluating local pressure gradient. Besides, the model is capable of accommodating the zone of reduced pressure (including intermediate and fluid lag zones) at the fracture front so as to capture the behavior of fracture tip region more realistically. A fully coupled poroelastic model for gas reservoirs has been also developed using an innovative numerical technique. From the results of this study it has been found that fracture propagation pressure is higher in poroelastic media compared to that of elastic media. Also high formation permeability (in the direction normal to the hydraulic fracture) and large difference between minimum horizontal stress (in case of it being the smallest principal stress) and reservoir pressure reduce the rate of fracture growth. Besides, high pumping rate is more beneficial in elongating a hydraulic fracture whereas high viscous fracturing fluid is advantageous in widening a hydraulic fracture. It has been also shown that rock deformation, permeability anisotropy and modulus of elasticity can have a significant effect on fluid flow in a hydraulically fractured reservoir. Furthermore, it has been shown that long stress reversal time window and large size of stress reversal region can be caused by high initial pressure differential (i.e. the difference between flowing bottomhole pressure and reservoir pressure), low initial differential stress (i.e. the difference between maximum and minimum horizontal stresses) and low formation permeability in tight gas reservoirs. By taking advantage of production induced change in stress state of a reservoir, this study has also shown that a refracture treatment, if carried out in an optimal time window, can lead to higher economic gain. Besides, analysis of stress reversal region has depicted that a small region with high stress concentration in the vicinity of the wellbore could impede refracture from initiating at the desired place. Moreover, re-pressurization of the wellbore can result in further propagation of the initial fracture before initiation or during propagation of the secondary fracture.
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Friehauf, Kyle Eugene. "Simulation and design of energized hydraulic fractures." 2009. http://hdl.handle.net/2152/6644.
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Hydraulic fracturing is essential for producing gas and oil at an economic rate from low permeability sands. Most fracturing treatments use water and polymers with a gelling agent as a fracturing fluid. The water is held in the small pore spaces by capillary pressure and is not recovered when drawdown pressures are low. The un-recovered water leaves a water saturated zone around the fracture face that stops the flow of gas into the fracture. This is a particularly acute problem in low permeability formations where capillary pressures are high. Depletion (lower reservoir pressures) causes a limitation on the drawdown pressure that can be applied. A hydraulic fracturing process can be energized by the addition of a compressible, sometimes soluble, gas phase into the treatment fluid. When the well is produced, the energized fluid expands and gas comes out of solution. Energizing the fluid creates high gas saturation in the invaded zone, thereby facilitating gas flowback. A new compositional hydraulic fracturing model has been created (EFRAC). This is the first model to include changes in composition, temperature, and phase behavior of the fluid inside the fracture. An equation of state is used to evaluate the phase behavior of the fluid. These compositional effects are coupled with the fluid rheology, proppant transport, and mechanics of fracture growth to create a general model for fracture creation when energized fluids are used. In addition to the fracture propagation model, we have also introduced another new model for hydraulically fractured well productivity. This is the first and only model that takes into account both finite fracture conductivity and damage in the invaded zone in a simple analytical way. EFRAC was successfully used to simulate several fracture treatments in a gas field in South Texas. Based on production estimates, energized fluids may be required when drawdown pressures are smaller than the capillary forces in the formation. For this field, the minimum CO2 gas quality (volume % of gas) recommended is 30% for moderate differences between fracture and reservoir pressures (2900 psi reservoir, 5300 psi fracture). The minimum quality is reduced to 20% when the difference between pressures is larger, resulting in additional gas expansion in the invaded zone. Inlet fluid temperature, flowrate, and base viscosity did not have a large impact on fracture production. Finally, every stage of the fracturing treatment should be energized with a gas component to ensure high gas saturation in the invaded zone. A second, more general, sensitivity study was conducted. Simulations show that CO2 outperforms N2 as a fluid component because it has higher solubility in water at fracturing temperatures and pressures. In fact, all gas components with higher solubility in water will increase the fluid’s ability to reduce damage in the invaded zone. Adding methanol to the fracturing solution can increase the solubility of CO2. N2 should only be used if the gas leaks-off either during the creation of the fracture or during closure, resulting in gas going into the invaded zone. Experimental data is needed to determine if the gas phase leaks-off during the creation of the fracture. Simulations show that the bubbles in a fluid traveling across the face of a porous medium are not likely to attach to the surface of the rock, the filter cake, or penetrate far into the porous medium. In summary, this research has created the first compositional fracturing simulator, a useful tool to aid in energized fracture design. We have made several important and original conclusions about the best practices when using energized fluids in tight gas sands. The models and tools presented here may be used in the future to predict behavior of any multi-phase or multi-component fracturing fluid system.text
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Perkins, Adam Reed. "An examination of state regulations of hydraulic fracturing." Thesis, 2014. http://hdl.handle.net/2152/26531.
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As hydraulic fracturing gains popularity in the energy industry, the state of Texas finds itself in a very advantageous position. With multiple regions which could have great potential for oil and natural gas extractable via the production technique, Texas has assumed a new importance for the energy industry. However, in order to fully utilize its advantages, the state of Texas should revise its oil and gas regulations, particularly with regard to groundwater use and contamination, air emissions, and discretion for municipal regulation of oil and gas operations, insofar as they may apply to hydraulic fracturing. This course of action only will this allow the state to efficiently utilize the production method while better balancing against the technique's risks.text
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Dong, Guangwei. "Modeling Performance of Horizontal Wells with Multiple Fractures in Tight Gas Reservoirs." 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8712.
Full textAbstract:
Multiple transverse fracturing along a horizontal well is a relatively new technology that is designed to increase well productivity by increasing the contact between the reservoir and the wellbore. For multiple transverse fractures, the performance of the well system is determined by three aspects: the inflow from the reservoir to the fracture, the flow from the fracture to the wellbore, and the inflow from the reservoir to the horizontal wellbore. These three aspects influence each other and combined, influence the wellbore outflow.
In this study, we develop a model to effectively formulate the inter-relationships of a multi-fracture system. This model includes a reservoir model and a wellbore model. The reservoir model is established to calculate both independent and inter-fracture productivity index to quantify the contribution from all fractures on pressure drop of each fracture, by using the source functions to solve the single-phase gas reservoir flow model. The wellbore model is used to calculate the pressure distribution along the wellbore and the relationship of pressure between neighboring fractures, based on the basic pressure drop model derived from the mechanical energy balance. A set of equations with exactly the same number of fractures will be formed to model the system by integrating the two models. Because the equations are nonlinear, iteration method is used to solve them. With our integrated reservoir and wellbore model, we conduct a field study to find the best strategy to develop the field by hydraulic fracturing. The influence of reservoir size, horizontal and vertical permeability, well placement, and fracture orientation, type (longitudinal and transverse), number and distribution are completely examined in this study. For any specific field, a rigorous step-by-step procedure is proposed to optimize the field.
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Yu-SenTseng and 曾雨森. "An Analysis of the Borehole Stability and the Hydraulic Re-fracturing Pressure in Deviated Wells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/23857397488948595924.
Full textAbstract:
碩士國立成功大學
資源工程學系碩博士班
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In order to avoid the collapse of borehole, the analysis of borehole stability is necessary before the start of the drilling project. There are many factors that affect the stability of the borehole wall, including earth stress, inclined orientation, formations physical properties, mud composition, and temperature of borehole. The hydraulic fracturing is widely used not only in the oil and gas exploration, but also in the earth stress measurements. In this study, we consider the factors including inclined orientation, earth stress, pore pressure, rock properties and discuss the range of the stable pressure by various stress conditions around the wellbore by stress analysis approach. In addition, Rummel’s(1987) fracture mechanics approach was used in this study to evaluate the hydraulic re-fracturing pressure under different inclined positions, earth stresses, fracture toughness, crack lengths, pore pressures in inclined state. The study shows that the different inclined orientations have different effects on the wellbore stability pressure. The range of stability pressure increases with the increasing of the overburden stress and decreases with the increasing of the lateral stress ratio. The increasing of pore pressure around borehole causes the range of stability pressure distinctly decreasing. When the cohesion and angle of internal friction of rocks are larger, the range of wellbore stability pressure becomes greater. The different stress states cause the different effects of inclined orientations. The re-fracturing pressure increases with the increasing of the overburden stress, and the re-fracturing pressure decreases slightly with the increasing of the lateral stress ratio. The rock fracture toughness does not affect the re-cracking pressure. In most cases, when the crack length is longer, the cracking pressure is larger. The rising of pore pressure around borehole wall causes decreasing in re-cracking pressure.
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Bryant, Stephen Andrew. "Simulating refracturing treatments that employ diverting agents on horizontal wells." 2013. http://hdl.handle.net/2152/22365.
Full textAbstract:
The use of hydraulic fracturing has increased rapidly and is now a necessary technique for the development of shale oil and gas resources. However, production rates from these plays typically exhibit high levels of decline. After one year, rates often decrease by over fifty percent. Refracturing – the process of hydraulically fracturing a well that has previously been fractured – is a proposed technique designed to offset these high decline rates and provide a sustainable increase in production. Benefits from refracturing can occur due to a variety of reasons, including the extension of fracture length, the increase in fracture conductivity or the reorientation of the fracture into new areas of the reservoir.
In this thesis, the simulation of refracturing treatments on horizontal wells with the use of a diverting agent is described. Diverting agents are used to distribute flow more evenly along the wellbore and to replace the use of costly downhole equipment employed to isolate sections of the wellbore. When diverting agent is deposited, a cake forms with an associated permeability. Flow is diverted from the fractures with high amounts of diverting agent because the larger cake results in a greater resistance to flow. The diverting agent cake breaks down with time at reservoir temperature so that production is uninhibited. Two different models are used to account for the application of diverting agent. One assumes the diverting agent cake forms in the perforation tunnel and the other assumes it forms in the fracture. The propagation of competing fractures is calculated using a computer code developed at the University of Texas called UTWID.
In both models, the simulations showed successful diversion of flow. Previously understimulated fractures – that is, shorter fractures or fractures that would grow less preferentially under normal fracturing treatments – grew at a faster pace after pumping of the diverting agent. A sensitivity analysis was conducted on several of the key refracturing design parameters, and the interdependence of the parameters was demonstrated. The simulations support the concept that diverting agents can be used to more evenly stimulate the entire length of the lateral.text
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Greiner, Lydia Hallacher. "To frack or not to frack: understanding community concerns about health and hydraulic fracturing." Thesis, 2017. https://hdl.handle.net/2144/27160.
Full textAbstract:
BACKGROUND: Over the past decade hydraulic fracturing, the high-pressure injection of water and chemicals into an oil or gas well, has been widely adopted to maximize oil and gas recovery despite debate about potential health impacts. Often the debate is contentious and complicated by incomplete information. The purpose of this dissertation was to implement and assess the usefulness of a process for communities to identify, prioritize, and respond to potential health effects of hydraulic fracturing.
METHODS: The study was conducted in a community in Kern County, California, the epi-center of hydraulic fracturing in the state. Mixed methods were used to develop an inventory of known or potential health effects associated with exposure to hydraulic fracturing: a systematic review of literature published before April 1, 2017 to determine health outcomes reported in exposed communities; a Delphi study to elicit expert opinion; and focus groups to determine residents’ health concerns. The resulting inventory of 60 health effects derived from one or more of these sources was presented to community residents in ballot form and multi-voting was used to prioritize health effects. Focus group and multi-voting results were used to develop an action plan.
RESULTS: The Delphi panel endorsed 13 health outcomes associated with hydraulic fracturing for oil and/or gas; all but one were reported in the scientific literature. Focus groups generated 17 health effects; 13 of these were reported in the scientific literature and/or endorsed by the Delphi panel. Multi-voting results indicated that priority health effects were: problems with sleep; breathing; eyes, ears, nose, and throat; heart disease and hypertension; cancer; headache; nausea; and a group of symptoms known as “Shale Gas Syndrome”.
CONCLUSION: The process described in this dissertation could be used by communities across the US that are debating the potential health impacts of hydraulic fracturing. It engages community residents, requires few resources, and can be completed in a relatively short period of time. The results can inform a community-specific response to the priority health concerns identified.
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Khan, Abdul Muqtadir. "Multi-frac treatments in tight oil and shale gas reservoirs : effect of hydraulic fracture geometry on production and rate transient." 2013. http://hdl.handle.net/2152/22367.
Full textAbstract:
The vast shale gas and tight oil reservoirs in North America cannot be economically developed without multi-stage hydraulic fracture treatments. Owing to the disparity in the density of natural fractures in addition to the disparate in-situ stress conditions in these kinds of formations, microseismic fracture mapping has shown that hydraulic fracture treatments develop a range of large-scale fracture networks in the shale plays.
In this thesis, an approach is presented, where the fracture networks approximated with microseismic mapping are integrated with a commercial numerical production simulator that discretely models the network structure in both vertical and horizontal wells. A novel approach for reservoir simulation is used, where porosity (instead of permeability) is used as a scaling parameter for the fracture width. Two different fracture geometries have been broadly proposed for a multi stage horizontal well, orthogonal and transverse. The orthogonal pattern represents a complex network with cross cutting fractures orthogonal to each other; whereas transverse pattern maps uninterrupted fractures achieving maximum depth of penetration into the reservoir. The response for a
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single-stage fracture is further investigated by comparing the propagation of the stage to be dendritic versus planar. A dendritic propagation is bifurcation of the hydraulic fracture due to intersection with the natural fracture (failure along the plane of weakness).
The impact of fracture spacing to optimize these fracture geometries is studied. A systematic optimization for designing the fracture length and width is also presented. The simulation is motivated by the oil window of Eagle Ford shale formation and the results of this work illustrate how different fracture network geometries impact well performance, which is critical for improving future horizontal well completions and fracturing strategies in low permeability shale and tight oil reservoirs.
A rate transient analysis (RTA) technique employing a rate normalized pressure (RNP) vs. superposition time function (STF) plot is used for the linear flow analysis. The parameters that influence linear flow are analytically derived. It is found that picking a straight line on this curve can lead to erroneous results because multiple solutions exist. A new technique for linear flow analysis is used. The ratio of derivative of inverse production and derivative of square root time is plotted against square root time and the constant derivative region is seen to be indicative of linear flow. The analysis is found to be robust because different simulation cases are modeled and permeability and fracture half-length are estimated.text
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Gaspar, Joana Henriques. "Os Estados Unidos da América e a Revolução do Shale." Master's thesis, 2015. http://hdl.handle.net/10362/17708.
Full textAbstract:
Ao longo dos últimos anos, tem-se verificado grandes mudanças no mercado
energético global, sendo os Estados Unidos da América um dos grandes
protagonistas.
A presente investigação tem como principal objetivo compreender e clarificar o
conceito de independência energética/auto-suficiência energética e averiguar a
possibilidade e o alcance deste propósito por parte dos Estados Unidos da América,
desde a Revolução do Shale.
Ao longo desta investigação haverá oportunidade de estudar as políticas
energéticas assumidas durante aproximadamente os últimos 40 anos, obter
informações sobre a segurança energética dos Estados Unidos, bem como formas de
exploração energética americana, política para exportação de energia e impactos
geopolíticos.
Facilmente se observa ao longo deste trabalho que a auto-suficência não pode
ser vista numa perspetiva de criação de condições para o isolacionismo americano
mas sim numa perspetiva de instrumentalização e proteção dos seus aliados.Over the past few years, there has been great changes in the Global energy market, with the United States of America as one of the major protagonists. The main goal of the present investigation is to understand and clarify the notion of energy Independence or Self-sufficiency and verify the possibility to achieve this goal, by the United States. Throughtout this research, there will be opportunity to study the US energy policies of the last 40 years, obtain informations about US energy security, and learn about american energy exploration, exports policy and geopolitical impacts of the Shale Revolution. Lastly, in this research it is easily observed that self-sufficiency can not be seen in a perspective of creating conditions for American isolationism but rather in a perspective of instrumentalization and protection of their allies