Thèses : « Fracturing fluids »

1

Kekacs, Daniel. « Treatment and Characterization of Hydraulic Fracturing Fluids ». The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406297620.

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Cluff, Maryam Ansari. « Microbial Aspects of Shale Flowback Fluids and Response to Hydraulic Fracturing Fluids ». The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366292190.

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Heyob, Katelyn M. « The Biodegradability of Polypropylene Glycols and Ethoxylated Surfactants within Hydraulic Fracturing Fluids ». The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440415027.

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Liu, Shuai. « Laboratory Investigations on the Geochemical Response of Groundwater-sediment Environment to Hydraulic Fracturing Fluids ». The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1376501759.

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O'Keeffe, Niall. « Fluid-driven fractures in elastic hydrogels : propagation and coalescence ». Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/287633.

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In this thesis we focus on a novel experimental exploration of fluid-driven fractures in a brittle hydrogel matrix. Fluid-driven fracturing is a procedure by which a fracture is initiated and propagates due to pressure applied by a fluid introduced inside the fracture. We describe how to construct the experimental setup utilised in this research, including how to synthesise polyacrylamide hydrogels to study the processes linked with fluid-driven fracturing. These transparent, linearly elastic and brittle gels permit fracturing at low pressures and speeds allowing accurate measurements to be obtained. The broad range of modulus and fracture energy values attainable from this medium allow the exploration of particular regimes of importance. Fracturing within these hydrogels also creates beautiful spiral patterns on the plastically deformed surfaces. We analyse these patterns and discuss their formation, while also commenting on their fractal-like nature. Initially, we study single fractures that are driven by an incompressible Newtonian fluid, injected at a constant rate into an elastic matrix. The injected fluid creates a radial fracture that propagates along a plane. We investigate this type of fracture theoretically and then verify the scaling predictions experimentally. We examine the rate of radial crack growth, fracture aperture, shape of the crack tip and internal fluid flow field. We exhibit the existence of two distinct fracturing regimes, and the transition between these, in which propagation is either dominated by viscous flow within the fracture or the material toughness. Particle image velocimetry measurements also strikingly show that the flow in the fracture can alter from an expected radial symmetry to circulation cells, dependent on the regime of propagation. We then expand our research to the problem of two coplanar fluid-driven radial fractures. This was chosen to focus on the physical mechanisms that are key to fracture network formation, related to many geophysical and industrial practices. Initially, the two fractures propagate independently of each other. At a critical separation they begin to interact, with non-uniform growth occurring along the fracture edges due to the evolving stress state in the gel matrix. When the radial extents of the fractures become sufficiently large, they coalesce and form a bridge between them. Following initial contact, a large increase in flow is seen into the newly created bridge and most of the growth is localised along this, perpendicular to the line connecting the injection sources. From experimental measurements, we observe a universal dynamic behaviour for the growth of this bridge. We model this universal behaviour theoretically and construct scalings related to the growth after coalescence, which again identifies both a viscous and toughness regime. The toughness regime is verified experimentally for the bridge growth and the universal shape of the thickness profile along the bridge. The coalesced fractures then transition into a single fracture at late times. Finally, we discuss a number of other interesting scenarios that may occur such as, non-coalescing fractures, asymmetric coalescence and ridge formation.

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Ohanian, Nicholas. « The Examination of Fiber and Breaker Effects on the Rheological and Settling Rate Characteristics of Hydraulic Fracturing Fluids ». The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417610323.

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Rocco, Stefano. « Some geological implications of the flow of clay-water mixtures ». Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/270525.

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This thesis investigates three problems in the general area of environmental fluid mechanics. The first two problems are related to liquid or gas flow through clay-water suspensions, with relevance for the underground storage of radioactive waste and also for understanding the mechanism of eruption in mud volcanoes. The third problem centres on the different problem of mixing in a turbulent buoyant plume. First, the injection of gas and water from a central source into a two-dimensional layer of clay confined between two circular horizontal plates is investigated. This provides a model of the potential pressurisation and failure of the seal rock around a radioactive waste repository as may arise if gas is continuously generated in the repository. As the gas injection pressure is gradually increased the cell walls deform and the clay moves radially outwards. However, at a critical radius, the liquid-clay interface becomes unstable and a series of channels propagate through the clay. When one of the channels reaches the edge of the domain the gas escapes and the pressure is released. As a result, the domain relaxes by elastic deformation and the clay seals the channel. In this way, continuous fluid injection leads to episodic release of gas from the cell. The second problem concerns the flow of mud along a vertical conduit driven by the combined effect of reservoir pressure and buoyancy associated with the gas injected at the base of the conduit. This represents an analogue model of the eruption of a mud volcano, in which mud rises from a deep reservoir to the surface. I find that the pressure associated with the reservoir and any buoyancy force produced by the migration of gas from deep in the reservoir to the surface leads to a continuous eruption if the net pressure is greater than the yield stress of the clay. If the reservoir pressure falls during such an event, the eruption will eventually stop, once the pressure reaches a dynamic yield stress condition. Only later, if the reservoir pressure increases to the static yield stress of the clay will the eruption start again, and this can lead to a series of eruption cycles which depend on the non-Newtonian rheology of the clay. In contrast, if this pressure is smaller than the yield stress of the clay, a series of episodic gas burst events can occur until the conduit is cleared of mud. The third problem relates to the mixing in a turbulent buoyant plume. Through a series of new experiments and some complementary theoretical modelling I show that the mixing in a turbulent plume is strongly affected by the eddies and leads to significant longitudinal dispersion in the flow. The implications of the modelling for determining the residence time distribution of the fluid in the plume is discussed.

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Salardon, Roland. « Fracturation, interactions fluides-roches et circulations fluides dans un bassin en hyper-extension puis lors de son inversion : Exemple des séries mésozoïques de la Zone Nord Pyrénéenne (Chainons Béarnais, France) ». Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0342/document.

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Les interactions entre la fracturation, les circulations fluides et la chimie des fluides au sein de marges hyper-étendues sont encore peu décrites et sont pour la plupart localisées en mer, enfouies sous des sédiments post-rift. Le bassin sud Aquitain et la partie nord des Pyrénées constituent un cas d’étude approprié pour l’investigation de ces interactions dans un modèle de marge hyper-étendue avec exhumation du manteau durant le Crétacé inférieur puis inversée. Les données de terrain ont permis de décrire trois principaux sets de fractures. Ils ont été corrélés aux principaux événements de l’évolution géodynamique du bassin correspondant au rifting triasique, à l’hyper-extension datée Aptien-Cénomanien, et à la compression pyrénéenne. Les observations pétrographiques, les analyses Raman et microthermométriques sur les inclusions fluides, les données acquises par ICP-MS, et les analyses isotopiques ont permis de déterminer les chimies, les températures, les conditions rédox, les compositions des gaz, les signatures isotopiques de l’oxygène et du carbone, et les teneurs en terres rares des fluides parents pour les ciments précipités durant chaque épisode. Ces données ont permis le calage temporel des évènements diagénétiques majeurs. En particulier, la dolomie baroque et la chlorite ont précipité dans les fractures du set 2 durant l’hyper-extension correspondant au pic thermique à des températures supérieures à 300°C. La signature isotopique, la forte teneur en CO2, l’occurrence de H2S et les fortes salinités des fluides parents suggèrent la percolation de fluides mantelliques ascendants au travers des évaporites triasiques. La phase fin et post hyper-extension est caractérisée par de la bréchification hydraulique dans les formations les plus poreuses, une baisse des températures et des salinités, une baisse de la contribution mantellique dans les fluides parents, une fermeture du système diagénétique au cours de l’enfouissement et un passage à des conditions réductrices durant la précipitation du quartz, de la pyrite et de la calcite. La phase de compression pyrénéenne associée au troisième stade de fracturation a induit une réouverture du système diagénétique et favorisé le retour à des conditions oxydantes et à des infiltrations de fluides météoriques
Interactions between fracturing, fluid circulations and fluid chemistry on hyper-extended margins is still poorly described as most of them are located offshore, buried underneath post-rift sediments. The southern Aquitaine basin and the northern Pyrenees constitute an appropriate case study to investigate these interactions since a model of hyper extended margin with mantle exhumation during the Lower Cretaceous subsequently inverted was recently proposed. From a field study, we here describe three main sets of fractures (set 1 to set 3). They are correlated with main stages of the geodynamic evolution of the basin corresponding to the Liassic rifting, the Aptian-Cenomanian hyper-extension, and the Pyrenean compression. Petrographic observations, Raman and micro-thermometry analysis on fluid inclusions, ICP-MS, and isotope analysis permitted to determine chemistries, temperatures, redox conditions, gas compositions, oxygen and carbon isotopic signatures, and REE contents of parent fluids for cements precipitated during each episode. In particular saddle dolomite and chlorite precipitated in set 2 fractures during the hyper-extension corresponding to the thermal peak at temperatures higher than 300°C. The isotopic signature, the high CO2 content, the occurrence of H2S and the high salinity of parent fluids suggest ascending mantle fluids percolating across Triassic evaporites. The late and post hyper-extensional phase is characterized by hydraulic brecciation in porous formations, a decrease in temperature and salinity, a decrease in mantle contribution in parent fluids, a closing of the diagenetic system during burial and a switch to reducing conditions during the precipitation of quartz, pyrite and calcite. The Pyrenean compressive phase associated with the third fracturing stage induced a reopening of the diagenetic system and favored a return to oxidizing conditions and infiltrations of meteoric fluids

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Eljarray, Abdelali. « Circulations fluides et altérations hydrothermales associées à des dépôts U (As, F) dans le massif de Saint Sylvestre (NW du massif central français) ». Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL009N.

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Ce travail consacre à l'étude des transferts de l'uranium aux différents stades hydrothermaux dans le massif de saint sylvestre (NW du M. C. F. ), et aux caractéristiques des perturbations d'ordre géochimique, minéralogique et structural qui leur sont associées, a été réalisée grâce à une approche pluridisciplinaire. Il a permis de connaitre: (1) la remobilisation tardive d'uranium hors du gisement et son ampleur; (2) les relations entre les différentes phases d'altération et la minéralisation primaire qui se traduisent par des marqueurs spécifiques et des orientations de réseaux de micro à macro-fracturation; (3) les conditions et la géométrie de développement des différents stades d'altération grâce à l'étude des fluides liées à ces stades. L'étude simultanée des circulations fluides, de la microfissuration et des altérations associées, a permis de: (1) envisager un développement des pièges d'uranium episyenite dans un système de fractures e-w, par un mécanisme de condensation de fluide aqueux type VW dont les caractéristiques sont, une faible salinité (<2% pds eq. Nacl) et une température élevée (350 a 400c); (2) définir les caractéristiques physicochimiques des fluides associes aux stades précoces à tardifs par rapport a la minéralisation uranifère. En effet, les stades précoces, sont caractérises par des fluides aquo-carboniques assez comparables (300 a 350c, salinité comprise entre 6 et 14% pds eq. Nacl) et par différents stades de piégeages de fluides aqueux

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10

Chang, Hong. « Hydraulic Fracturing in Particulate Materials ». Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4957.

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For more than five decades, hydraulic fracturing has been widely used to enhance oil and gas production. Hydraulic fracturing in solid materials (e.g., rock) has been studied extensively. The main goal of this thesis is a comprehensive study of the physical mechanisms of hydraulic fracturing in cohesionless sediments. For this purpose, experimental techniques are developed to quantify the initiation and propagation of hydraulic fractures in dry particulate materials. We have conducted a comprehensive experimental series by varying such controlling parameters as the properties of particulate materials and fracturing fluids, boundary conditions, initial stress states, and injection volumes and rates. In this work, we suggest principle fundamental mechanisms of hydraulic fracturing in particulate materials and determine relevant scaling relationships (e.g., the interplay between elastic and plastic processes). The main conclusion of this work is that hydraulic fracturing in particulate materials is not only possible, but even probable if the fluid leak-off is minimized (e.g., high flow rate, high viscosity, low permeability). Another important conclusion of this work is that all parts of the particulate material are likely to be in compression. Also, the scale effect (within the range of the laboratory scales) appears to be relatively insignificant, that is, the observed features of fractures of different sizes are similar. Based on the observed fracture geometries, and injection pressures we suggested three models of hydraulic fracturing in particulate materials. In the cavity expansion or ??e driving model, the fracturing fluid is viewed as a sheet pile (blade) that disjoints the host material, and the cavity expansion occurs at the fracture (blade) front. The shear banding model is also consistent with a compressive stress state everywhere in the particulate material and explains the commonly observed beveled fracture front. The model of induced cohesion is based on the fluid leak-off ahead of the fracture front. The induced cohesion may be caused by the tensile strain near the fracture tip (where the stress state is also compressive), which, in turn, induces the cavitation of the leaked-off fluid and hence capillary forces.

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Yi, Tongchun. « Numerical simulation of fluid loss in hydraulic fracturing treatments ». Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/779.

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GUIMARAES, GLAUCE DA SILVA. « ANALYSIS OF THE RHEOLOGICAL CHARACTERISTICS OF A HYDRAULIC FRACTURING FLUID ». PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1989. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33266@1.

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Como parte da linha de pesquisa na área de estimulação de poços de petróleo, foi montado um viscosímetro tubular para análise das características de comportamento reológico de um fluido de fraturamento hidráulico (HPGUAR), dotado de dispositivo para preparação do fluido . Os dados experimentais obtidos foram tratados analiticamente segundo dois tipos de equações constitutivas: as do Modelo de Ostwald, amplamente utilizadas pelos pesquisadores da área de Engenharia de Petróleo, e as do Modelo de Bingham. Pela avaliação dos resultados obtidos, pode-se concluir que parecem ocorrer evidências de que o Modelo de Bingham possa ser mais adequado, por retratar de forma mais independente as contribuições isoladas do atrito viscoso e da componente gerada pela viscosidade plástica, na análise teológica do HPGUAR. Sugere-se que investigações mais detalhadas devam ser conduzidas, posto que eventualmente poderiam ser bastante úteis no esclarecimento da pendência existente nos resultados experimentais obtidos por diversos autores consultados.
In order to contribute in the investigation of the stimulation operation of an oil reservoir was built a tubular viscometer to determine the rheological properties of a hydraulic fracturing fluid (HPGUAR). This test rig included a system to prepare the hydraulic fracturing fluid. The experimental results were modelled according to two types of constitutive equations: the Ostwald Model one, widely used in the Petroleum Engineers field, and the Bingham Model one. An evaluation of the experimental results suggests that the Bingham Model should be more adequate than the other one, specifically when it shows the contribuition from the viscous friction and from the plastic viscosity independently, in the determination of the rheological properties of the HPGUAR. More detailed investigations must be carried out, although they should be very usefull in better explaning the differeces obtained among several investigators.

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al-Najafi, Falah. « Dynamic fluid loss characteristics of linear fracturing gels and associated permeability impairment ». Thesis, Heriot-Watt University, 1986. http://hdl.handle.net/10399/862.

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Gehne, Stephan. « A laboratory study of fluid-driven tensile fracturing in anisotropic rocks ». Thesis, University of Portsmouth, 2018. https://researchportal.port.ac.uk/portal/en/theses/a-laboratory-study-of-fluiddriven-tensile-fracturing-in-anisotropic-rocks(ba904551-8672-4db8-8e90-56cf03c76a26).html.

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Fluid-driven tensile failure is a ubiquitous phenomenon in Earth sciences, as seen in examples ranging from dyke and sill injection in volcanic systems to veining and mineralisation. In the engineered environment, the method has recently been used for the intentional hydraulic fracture of water and hydrocarbon reservoirs. This has allowed the exploitation of previously uneconomic reservoirs by generating tensional fracture networks for enhanced permeability, but with the side effect of generating small earthquakes in the process. This has made the application of the technology controversial, as it generates a clear inherent risk. Although this industrial application has proven itself, it has developed in a largely uncontrolled trial-and-error approach and with little regard to the fundamental science behind the process. This is important, as to understand and predict the fracture process, the various controlling factors must be known, which is challenging in a natural environment. To address some of these gaps in knowledge, this study has developed a novel laboratory-based method to simulate the fluid-mechanical process of hydraulic fracturing. New data are presented that illustrate the combined effects of the inherent rock anisotropy, fabric and initial permeability, and how this is manifested in terms of tensile fracture initiation, propagation and geometry. To achieve this, a new apparatus to generate fluid-driven tensile fractures using a conventional triaxial cell (providing simulated burial depth) is developed. Rock physics data from the experiments (Acoustic Emission, radial strain and fluid pressures) recorded at high speed are combined with post-test micro X-ray CT imaging. For the first time, the generation and propagation of fluid-induced hydraulic fractures is made with respect to the initial rock fabric, and then linked to the generated Acoustic Emission, for direct comparison to field seismicity. Fracture orientation is primarily controlled by the principal stresses and their orientation relative to bedding planes. However, inherent rock anisotropy, initial rock permeability and rock fabric are key controlling factors in governing fracture initiation, propagation, and fracture geometry. It has been shown that anisotropy and initial permeabilities affect fracture initiation and can lead to increased or premature failure pressures respectively. Fracture geometry strongly depends on the orientation of the inherent bedding, determining if fractures propagate parallel or normal to the bedding, and the rock fabric, resulting in planar or more tortuous fracture paths. By linking Acoustic Emission and mechanical behaviour with respect to the final fracture network, the hydraulic fracture process is decoded into distinct fracture stages: (i) maximum fluid pressure, (ii) a short period of 'plastic' deformation, (iii) fracture initiation, (iv) stable fracture propagation, (v) sample breakdown and finally (vi) unstable fracture propagation. This analysis shows that a combination of seismic activity, fluid injection rates and deformation are reliable indicators for imminent breakdown in anisotropic sedimentary rocks subjected to injection fluid pressures, a critical step towards the development of an updated, engineered approach to hydraulic fracturing in an effort to reduce risks, increase controllability and to optimise gas extraction. Finally, the incremental fracture process is analysed and related to the fracture toughness (KIC) using fracture energy as a proxy to show that fracture extension only occurs when fluid-driven stress increases beyond KIC, whereas fracture initiation is controlled by the tensile strength. Ultimately, relating fracture behaviour in unconventional resource lithologies to induced seismicity and key mechanical and fluid injection parameters may provide for better fracture prediction during field operations, reducing the risk and improve resource exploitation.

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Alseamr, Nisreen. « A Theoretical Simulation of the Settling of Proppants in a Hydraulic Fracturing Process ». VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4272.

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Hydraulic fracturing is a process for the extraction of hydrocarbons from underground formations. It involves pumping a specialized fluid into the wellbore under high pressures to form and support fractures in the rock. Fracturing stimulates the well to increase the production of oil and the natural gas which are the pillars of the energy economy. Key to this process is the use of proppants, which are solid materials used to keep the fractures open. Understanding the transport of proppant particles through a fluid is important to improve the efficiency and reduce environmental impact of fracturing. An increase of the settling velocity for instance, will impede the hydraulic fracturing process by reducing well productivity, or necessitate use of chemical additives. This thesis presents a theoretical investigation of the settling velocity of proppant particles. The effect of different parameters on the settling velocity were studied by manipulating the main factors that can influence particle transport. These include size of the particle (300 μm- 2000 μm), sphericity, density (1200 kg/m3-3500 kg/m3) and concentration. These typical values were obtained from commercially available proppants currently used in industry. Various correlations were investigated, assuming the carrier (fracturing) fluid to be an ideal Newtonian and as a power law (non-Newtonian) fluid. This will help predict the settling velocity for proppant particles in order to increase well productivity, and improve hydraulic fracturing efficiency. The models show that changing the carrier fluid viscosity and particle properties such as diameter, density, sphericity, and concentration leads to a significant change in the proppant settling velocity. For instance, reduction in particle size, density, and sphericity tend to reduce the settling velocity, while increasing the concentration of the particles and the fluid viscosity reduce the settling velocity.

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Fletcher, Sarah Marie. « Risk assessment of groundwater contamination from hydraulic fracturing fluid spills in Pennsylvania ». Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/72885.

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Thesis (S.M. in Technology and Policy)-- Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 109-115).
Fast-paced growth in natural gas production in the Marcellus Shale has fueled intense debate over the risk of groundwater contamination from hydraulic fracturing and the shale gas extraction process at large. While several notable incidents of groundwater contamination near shale gas wells have been investigated, the exact causes are uncertain and widely disputed. One of the most frequently occurring and widely reported environmental incidents from shale gas development is that of surface spills. Several million gallons of fluid are managed on each well site; significant risk for spill exists at several stages in the extraction process. While surface spills have been primarily analyzed from the perspective of surface water contamination, spills also have the potential to infiltrate groundwater aquifers. This thesis develops a risk assessment framework to analyze the risk of groundwater resource contamination in Pennsylvania from surface spills of hydraulic fracturing fluid. It first identifies the major sources of spills and characterizes the expected frequency and volume distribution of spills from these sources using results from a preliminary expert elicitation. It then develops a stochastic groundwater contaminant transport model to analyze the worst-case potential for groundwater contamination in local water wells. Finally, it discusses the range of risk perception and incentives from a wide-ranging stakeholder base, including industry, communities, environmentalists, and government. This thesis concludes that while the vast majority of shale gas operations do not result in large spills, the worst-case potential for groundwater contamination is high enough to warrant further attention; it also recommends increased inclusion of community stakeholders in both industry and government risk management strategies.
by Sarah Marie Fletcher.
S.M.in Technology and Policy

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Sousani, Marina. « Modeling of hydraulic fracturing in rocks : a multiscale and fluid-solid coupling approach ». Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/9607/.

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This dissertation investigates the implications of the fluid flow on the behaviour of the particle-scale structure of a porous hard rock, based on the Discrete Element Method (DEM). This project is driven by the need to contribute towards a better understanding of the mechanical behaviour of porous rock formations under intense injection conditions and the influence of natural pre-existing rock damage to the hydraulic fracturing mechanism. The proposed numerical scheme incorporates different methods for computing both the solid and co-existing fluid phases. The solid phase (rock sample) has been characterized as a collection of discrete interacting particles, bound by spring-like contacts according to the DEM. Meanwhile, the fluid phase has been modelled by discretising the Navier-Stokes equations for porous media, utilising the fluid coupling algorithm embedded in the Particle Flow Code (PFC3D) software by Itasca. The outcome of this dissertation suggests that the DEM approach is an advanced computational method that can reproduce accurate rock models, adequately describe the inter-particle dynamics and thus contribute towards direct numerical and experimental comparisons, and interpret the geo-mechanical behaviour of the rock materials. Furthermore, this study identifies the importance of shear cracking in the hydraulic fracturing models, whereas conventional theory relates hydraulic fracturing with tensile cracking. Finally, this study focuses on the influences of various parameters, such as the external stress regime, fluid viscosity and pre-existing fractures, on the mechanical behaviour of the rock material in the particle-scale and the hydraulic fracturing process as a whole. This work is in an early stage and it aims to simulate hydraulic fracturing experiments with the use of a 3D modelling and the DEM approach, and to investigate the micromechanical response of the rock. Further research may include areas such as the 3D modelling of pre-cracked rocks using a larger variety of fracture angles.

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Bennour, Ziad. « Effect of Hydraulic Fracturing Fluid Viscosity on Stimulated Reservoir Volume for Shale Gas Recovery ». 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225563.

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Turkaya, Semih. « Understanding the evolution of channeling and fracturing in tight rocks due to fast fluid flow ». Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAH021/document.

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Depuis de nombreuses années, la compréhension de l'influence des fluides dans la déformation des roches est un enjeu majeur pour de nombreux scientifiques. Dans le cadre de ce projet de recherche, notre attention s’est focalisée sur l’observation et la modélisation des mécanismes d’interaction entre les parties fluide et solide lors de l’aérofracturation d’un milieu poreux. Notre dispositif expérimental reproduit le phénomène à basse pression et dans un système pertinent pour l’analyse optique, grâce à une cellule de Hele‐Shaw rectangulaire dans laquelle se trouve un milieu granulaire soumis à des écoulements de fluide interstitiel. Dans les expériences et les simulations nous avons observé ce que l’amplitude de la partie de fréquence basse du spectre puissance diminue avec la fracturation en progrès. Aussi, nous avons développé une méthode pour focaliser les ondes ce qui peut être utiliser pour estimer la position de la source
Fluid induced brittle deformation of porous medium is a phenomenon commonly present in everyday life. From an espresso machine to volcanoes it is possible to see traces of this phenomenon. In a rectangular Hele‐Shaw cell we inject air into a loose porous medium. Then, we monitor this system using optical imaging using a high speed camera (1000 fps) and 4 high frequency resolution accelerometers. Using the numerical and experimental acoustic emissions, different sources of the recorded signal (vibrations due to air, changes in the effective stress due to fluid‐solid interactions) are analyzed. We found that, the peaks in the low frequency range (f < 20 kHz) diminishes while the medium fractures. Furthermore, we propose a new signal localization method based on energy amplitude attenuation and inversed source amplitude comparison. Furthermore, using optical and acoustic datasets and numerical simulations, the mechanics leading Type‐A and Type‐B earthquakes are explained

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Cornejo, Velázquez Alejandro. « A fully Lagrangian formulation for fluid-structure interaction between free-surface flows and multi-fracturing solids ». Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/670376.

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It is well known that in civil engineering structures are designed so that they remain,whenever possible, in an elastic regime and with their mechanical properties intact. The truth isthat in reality there are uncertainties either in the execution of the work (geometric errors ormaterial quality) or during its subsequent use (loads not contemplated or its value has beenestimated incorrectly) that can lead to the collapse of the structure. This is why the study of thefailure of structures is inherently interesting and, once is known, its design can be improvedto be the less catastrophic as possible or to dissipate the maximum energy before collapsing.Another area of application of fracture mechanics is that of processes of which interest liesin the breakage or cracking of a medium. Within the mining engineering we can enumerateseveral processes of this nature, namely: hydraulic fracture processes orfracking, blasting fortunnels, explosion of slopes in open pit mines, among others. Equally relevant is the analysis ofstructural failures due to natural disasters, such as large avenues or even tsunamis impactingprotection structures such as walls or dikes. In this work numerous implementations and studieshave been made in relation to the mentioned processes.That said, the objective of this thesis is to develop an advanced numerical method capableof simulating multi-fracture processes in materials and structures. The general approach ofthe proposed method can be seen in various publications made by the author and directorsof this thesis. This methodology is meant to cover the maximum spectrum of engineeringapplications possible. For this purpose, a coupled formulation of theFinite Element Method(FEM) and theDiscrete Element Method(DEM) is used, which employs an isotropic damageconstitutive model to simulate the initial degradation of the material and, once the strength ofthe material has been completely exhausted, thoseFinite Element(FE) are removed from theFEMmesh and a set ofDiscrete Element(DE) are generated at its nodes. In addition to ensurethe conservation of the mass of the system, theseDEprevent the indentation between thefissure planes thanks to the frictional repulsive forces calculated by theDEM, if any.Additionally, in this thesis it has been studied how the proposed coupled method namedFEM-DEMtogether with the smoothing of stresses based on thesuper-convergent patchisable to obtain reasonably mesh-independent results but, as one can imagine, the crack width isdirectly related to the size of the elements that have been removed. This favours the inclusionof an adaptive remeshing technique that will refine the mesh where it is required (according tothe Hessian of a nodal indicator of interest) thus improving the discretization quality of the crackobtained and thereby optimizing the simulation cost. In this sense, the procedures for mappingnodal and internal variables as well as the calculation of the nodal variable of interest will bediscussed.As far as the studies of natural disasters are concerned, especially those related to free-surface water flows such as tsunamis, one more level of coupling between the aforementionedmethodFEM-DEMand oneComputational Fluid Dynamics(CFD) formulation commonlyreferred to asParticle Finite Element Method(PFEM) has been implemented. With this strongcoupled formulation, many cases of wave impacts and fluid flows have been simulated agains solid structures such as walls and dikes, among others.
Es bien sabido que en ingeniería civil las estructuras se diseñan para que permanezcan, siempre que sea posible, en régimen elástico y con sus propiedades mecánicas intactas. Lo cierto es que en realidad existen incertidumbres tanto en la ejecución de la obra (errores geométricos o de calidad de los materiales) como en su posterior utilización (cargas no contempladas o cuyo valor y/o punto de aplicación se ha estimado incorrectamente) que pueden conllevar al colapso de la estructura. Por ello, el estudio del fallo de las estructuras es inherentemente interesante y, una vez conocido, se puede mejorar el diseño de la misma para que sea lo menos catastrófico posible o para que disipe la máxima energía antes del colapso y aumentar así su ductilidad y seguridad. Otra área de aplicación de la mecánica de la fractura es la de los procesos cuyo interés radica en la rotura o la fisuración de un medio. Dentro de la ingeniería de minas podemos enumerar varios procesos de esta naturaleza, a saber: procesos de fractura hidráulica o fracking, voladuras para excavación de túneles, explosión de taludes en minas a cielo abierto, entre otros. Igualmente relevante es el análisis de los fallos estructurales debidos a desastres naturales, como grandes avenidas o incluso tsunamis que impactan en estructuras de protección como muros o diques. En este ámbito se han realizado numerosas implementaciones y estudios en relación con los procesos mencionados. Dicho esto, el objetivo de esta tesis es desarrollar un método numérico avanzado, cuyo enfoque general puede verse en diversas publicaciones realizadas por el autor y los directores de esta tesis, capaz de simular procesos de multifractura en materiales y estructuras cubriendo así el máximo espectro de aplicaciones de ingeniería posible. Para ello se emplea una formulación acoplada del Método de los Elementos Finitos (FEM) y del Método de los Elementos Discretos (DEM), que internamente incluye un modelo constitutivo de daño isótropo para simular la degradación irrecuperable del material. Una vez agotada la energía de deformación disponible de algunos elementos finitos (FE), se eliminan de la malla FEM y se genera un conjunto de elementos discretos (DE) en los nodos del mismo. Los DE generados, además de asegurar la conservación de la masa del sistema, evitan la indentación entre los planos de la fisura gracias a las fuerzas friccionales de repulsión calculadas por el DEM, si las hubiere. En esta tesis se ha estudiado cómo el método acoplado propuesto denominado FEM-DEM junto con el suavizado de tensiones basado en el super-convergent patch es capaz de obtener resultados razonablemente independientes de la malla pero, como se puede imaginar, el ancho de la fisura está directamente relacionado con el tamaño de los elementos finitos que se han eliminado. Esto propicia la inclusión de una técnica de remallado adaptativo que refinará la malla donde se requiera (según la matriz Hessiana de un indicador nodal) mejorando así la calidad de discretización de la fisura obtenida y optimizando el coste computacional de la simulación. En este sentido, se discutirán los procedimientos de mapeo de las variables nodales e internas, así como el cálculo de la variable nodal de interés. En lo que respecta al estudio de los desastres naturales, especialmente los relacionados con flujos de agua de superficie libre como los tsunamis, se ha implementado un nivel más de acoplamiento entre el mencionado método FEM-DEM y una formulación de Dinámica de Fluidos Computacional (CFD) comúnmente conocida como Método de Elementos Finitos y Partículas (PFEM). Con esta formulación fuertemente acoplada, se han simulado diversos casos de impactos de olas contra estructuras sólidas como muros y diques, entre otros.

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Kobchenko, Maya. « Fracturation durant la production interne de fluides dans les roches : application à la migration primaire d'hydrocarbures ». Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENU035/document.

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Cette thèse presente des travaux et résultats d'expériences de fracturation dont l'origine est une génération interne de fluides induite par des réactions chimiques dans des échantillons de roches et des matériaux analogues. Les deux premiers articles portent sur une expérience avec des échantillons de schistes imagés par tomographie aux rayons X au cours du temps. Le premier article décrit la formation de fractures créées par l'augmentation de pression induite par la décomposition de matière organique lorsque les schistes sont chauffés. Le deuxième article porte sur la procédure expérimentale et l'analyse d'images, utilisées pour obtenir les résultats du premier article. Les deux autres articles concernent la fracturation d'une couche de gélatine contenant de la levure et du sucre, ce qui génère du CO2. Le troisième article décrit le mécanisme de formation d'un réseau de fractures au cours du drainage du CO2 contenu dans la gélatine. Le quatrième article concerne l'évolution du réseau de fractures au cours de ce drainage, ainsi que les mécanismes d'ouverture et fermeture des fractures. Le dernier article porte sur une étude par tomographie aux rayons X de la distribution de porosité d'échantillons endommagés d'andésite. Les méthodes développées dans ce projet peuvent s'appliquer à la déshydratation de sédiments, la formation de volcans de boue, l'exploration d'hydrates de méthane, la séquestration de CO2 et la fracturation de réservoirs non conventionnels
This thesis presents the experimental work and the results on fracturing of rock samples and analogue materials due to internal fluid generation during chemical reaction. The first two papers concentrate on time-resolved 3D X-ray imaging experiment on organic-rich shale samples. Paper 1 describes fracture formation due to hydrocarbon generation in the shale induced by organic matter decomposition during heating. Paper 2 gives an overview of the experimental procedure and image analysis workflow, which were used to obtain results presented in the first paper. The other two papers are focused on fracturing of gelatin mixed with yeast and sugar, which generates CO2. Paper 3 describes the mechanism of fracture network formation during draining of CO2 out of a gelatine layer. Paper 4 focuses on the temporal evolution of the drainage network and the mechanism of fracture opening and closing. The last paper presents a study in which X-ray microtomography was used to characterize porosity distribution in weathered andesite samples. The scientific methods developed in this project have potential application in studying dehydration of sediments, formation of mud volcanoes, methane hydrate exploration and assessment, geological sequestration of carbon dioxide CO2 and hydraulic fracturing of unconventional reservoirs

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SANTOS, PAULO ROBERTO DA FONSECA. « EVALUATING CHARACTERISTICS OF STATIC AND DYNAMIC FILTRATION OF A FLUID USED IN HYDRAULIC FRACTURING AT ROOM TEMPERATURE ». PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1989. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33262@1.

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Este trabalho teve como objetivo estudar as características de filtração estática e dinâmica de um fluido usado em fraturamento hidráulico à temperatura ambiente. Para sua realização foi projetado, desenvolvido e qualificado metrologicamente um simulador que permitisse efetuar testes de filtração estática e dinâmica. Foram realizadas filtrações com um fluido newtoniano (água) e um não newtoniano (HPGUAR-BO lbm/1000gal).
This research intended to study the characteristcs of dynamic and static leakoff of a fluid in hydraulic fracturing at room temperature. A test apparatus was designed, constructed and metrologically qualified in order to carry out dynamic and stactic leakoff test. Leakoffs with a Newtonian fluid (water) and with a non-Newtonian one (HPGUAR-BO lbm/1000 gal) were performed.

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Chen, Zipeng. « A Smoothed Particle Hydrodynamics Approach for Modelling Meso-scale Fluid–Fracture Interaction ». Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/28188.

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The fluid–fracture interaction at meso-scale is vital in numerous applications and challenging for numerical studies. During this process, the solid deforms or even damages due to the force transmitted from the surrounding fluid, whereas the deformation and failure of the solid in turn change the flow behaviour. Besides, the surface tension and wettability at meso-scale can have considerable effects on fluid behaviour. As a particle-based approach, the smoothed particle hydrodynamics (SPH) has shown its capability in modelling the flow at multiscale and potential in reproducing the fracture. Therefore, to model the fluid–fracture interaction at meso-scale, this thesis aims to develop a modified SPH method considering the surface tension of fluid and the fracture propagation of solids at meso-scale. In this approach, an interparticle force that can provide repulsive force in a short-range and attractive force in a long-range is introduced to model the fluid–fluid and fluid–solid interactions. Compared to traditional methods modelling the surface tension and wettability, the proposed interparticle force can be employed in complex geometry without explicitly identifying the fluid–solid interface. The formation of a droplet with surface tension and the change of contact angles on fluid–solid interface demonstrate the capability in reproducing the mesoscopic effects. Moreover, this interparticle force can prevent the SPH particles from clustering when under great pressure. The compressibility of the pipe flow is consistent with the physical value of water without particle clustering. This interparticle force is then coupled with the no-slip boundary to expand its application range. The simulation results of the Couette flow and the Poiseuille flow are consistent with the analytical solution, showing the feasibility of using this approach in the pipe flow under a no-slip boundary. For the solid part, the Drucker–Prager (DP) model and the Grady–Kipp (GK) damage model are combined and implemented to describe the shear failure and tensile failure, respectively. A shear analytical model a biaxial compressive model and a uniaxial compressive experiment are simulated. The results show that the implemented DP model reproduces the shear failure well. After calibrating the GK damage model through the available uniaxial tensile test, the DP model is combined with the GK damage model. A Brazilian disc test is then simulated. The numerical results reproduce the fracture patterns consistent with the experimental ones, showing the feasibility of using this mixed solid model to express the complex fracture of rock-like material. Finally, by coupling the fluid model and the solid model, an SPH framework is formed to consider the surface tension and fracture of the solid. A process of hydraulic fracturing is simulated at the meso-scale with different in-situ stress conditions. Moreover, a pre-existing flaw is added in the solid domain to investigate the influence of natural fracture in hydraulic fracturing. The results suggest that tensile failure is the dominant failure type controlling the fracture pattern of hydraulic fracturing. Moreover, since the in-situ stress state and the pre-existing flaw have mutual effects, the hydraulic fracturing should be analysed comprehensively. All the results prove that this modified SPH method had considerable potential in modelling the fluid–fracture interaction with the consideration of the surface tension effects of fluid and the fracture propagation of solid.

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Bonson, Christopher G. « Fracturing, fluid processes and mineralisation in the Cretaceous continental magmatic arc of Northern Chile (25°15'-27°15'S) ». Thesis, Kingston University, 1998. http://eprints.kingston.ac.uk/20612/.

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The structural geology of the Coastal CordiIIera of northern Chile (25°15'-27°15'S) is dominated by three fracture systems: (1) the margin-parallel, trench-linked Atacama Fault Zone (AFZ), (2) a northwest¬trending network of faults, and (3) northeast-trending discrete fracture zones. The margin-oblique fracture sets appear to relate to magnetic fabrics imaged deep in the lithosphere and suggests that these fault zones utilise long-lived zones of weakness. The interaction of these fractures was an important structural control on the focusing of melts and ore fluids' in the leading edge of the Andean margin. Magnetite-dominated deposits comprise one major style of genetically-related mineral deposits within the study area. Primary' fluids from a magnetite-apatite deposit (Carmen) are moderate to highly saline (c. 17 to 37wt% NaCl eq.), Na-Ca-Fe±Mg-Cl-H20 brines. Magnetite from the main-stage of mineralisation was precipitated from a fluid with a high alSo content of circa lO%lIvs SMOW, at temperatures of -300 to 500°C and a mean depth of -2.5km, indicating a magmatic provenance of these magnetite deposits. Comb and dendritic textures indicate precipitation from a low viscosity ore fluid, consistent with fluid densities of 0.9 to 1.lg/cm3 and high contents of Cl, F and H20. These data point to a submagmatic origin of the ores. The second major type of fracture-controlled mineralisation in the Coastal CordiIIera are fault-hosted veins and breccia-pipes of specular haematite-cha1copyrite ore. They are found in close spatial relationship with magnetite-dominated styles of mineralisation and are thought to have formed by cooling and oxidation of an originally magnetite-bearing ore fluid, by mixing with a carbonate-bearing, extraneously sourced fluid. This explains the intergrowth of ore minerals with calcite and/or siderite, and the geological setting of these deposits, under a carbonate-precipitating, shallow-marine marginal basin, which is tentatively suggested to source the extraneous fluid. Further investigation is needed to confirm this. A first-order structural control on the distribution of magnetite-dominated deposits is imposed by the Atacama Fault Zone, due to its role in the emplacement of dioritic and granodioritic magmas, which are the likely sources of the magnetite-mineralisation. Magnetite-dominated deposits were emplaced along broadly north-south-trending brittle and mylonitic segments of the sinistral AFZ. The structural controls on the mineralisation imposed by brittle faults are not fully understood. In several of the larger deposits, east¬northeast-fractures are important, although their precise role remains obscure. Magnetite-dominated mineralisation along the mylonitic shear zones of the AFZ and Chivato Fault Zone, appear associated with cyclic deformation. This is linked to pulses of hydrothermal fluids expelled from an intrusion, or episodic fluid flow accompanying high coseismic strain rates, experienced by the mylonites due to their high crustal level. The structural control on the haematite-cha1copyrite breccias is imposed by northwest trending faults. Breccia-pipes and veins are located in dilationaI sites along these faults, such as jogs and/or fault bends. Their textures may also interpreted to relate to the earthquake cycle. Along the AFZ belt of brittle and mylonitic shear zones, haematite-cha1copyrite-bearing, northwest-trending fractures commonly cross-cut the north-south oriented, magnetite bodies. This represents a change in the predominant structures which focused hydrothermal fluids throughout the evolution of a mineralising system. A model is proposed in which, 'locking-up' of the mylonite occurs as the temperature passes through the quartz plastic-brittle transition temperature (-300°C). This causes deformation to switch from localised displacements along the mylonitic shear zones of the AFZ, to more distributed deformation along 'basement-controlled' northwest faults. These faults are more favourable to accommodate displacements due to their orientation and that they are probably nucleated upon inherited zones of crustal weakness. The temperature of the brittle-ductile transition is approximately intermediate between the formation temperatures of the two classes of Fe-oxide deposit, hence switching of the fracture kinematics is broadly contemporaneous, with the change in mineralisation style.

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Wong, John Kam-wing. « Three-dimensional multi-scale hydraulic fracturing simulation in heterogeneous material using Dual Lattice Model ». Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/270542.

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Hydraulic fracturing is a multi-physics multi-scale problem related to natural processes such as the formation of dikes. It also has wide engineering applications such as extraction of unconventional resources, enhanced geothermal energy and carbon capture and storage. Current simulators are highly simplified because of the assumption of homogeneous reservoir. Unconventional reservoirs are heterogeneous owing to the presence of natural fracture network. Because of high computational effort, three-dimensional multi-scale simulations are uncommon, in particular, modelling material as a heterogeneous medium. Lattice Element Method (LEM) is therefore proposed for multi-scale simulation of heterogeneous material. In LEM, material is discretised into cells and their interactions are modelled by lattices, hence a three-dimensional model is simplified to a network of one-dimensional lattice. Normal, shear and rotational springs are used to define the constitutive laws of a lattice. LEM enables desktop computers for simulation of a lattice model that consists of millions of lattices. From simulations, normal springs govern the macroscopic bulk deformation while shear springs govern the macroscopic distortion. There is fluctuation of stresses even under uniform loading which is one of the characteristics of a lattice model. The magnitude increases with the stiffness ratio of shear spring to normal spring. Fracturing process can be modelled by LEM by introducing a microscopic tensile strength and a microscopic shear strength to the lattice properties. The strength parameters can be related to fracture toughness with the length scales of cells. From simulations, the relationships between model parameters and macroscopic parameters that are measurable in experiments are identified. From the simulations of uni-axial tension tests, both the spring stiffness ratio and the applied heterogeneity govern the fracturing process. The heterogeneity increases the ductility at the expense of the reduction on the macroscopic strengths. Different stages of fracturing are identified which are characterised by the model heterogeneity. Heterogeneous models go through the stages of the spatially distributed microscrack formation, the growth of multiple fracture clusters to the dominant fracture propagation. For homogeneous models, one of the microcracks rapidly propagates and becomes a dominant fracture with the absence of intermediate stages. From the uni-axial compression test simulations, the peak compressive stress is reached at the onset of the microscopic shear crack formation. Ductility is governed by the stiffness reduction ratio of a lattice in closed fractured stage to its unfractured stage. A novel Dual Lattice Model (DLM) is proposed for hydraulic fracture simulation by coupling a solid lattice model with a fluid lattice model. From DLM simulations of hydraulic fracturing of the classical penny shape crack problem under hydrostatic condition, the heterogeneities from both the fracture asperity and the applied heterogeneity increase the apparent fracture toughness. A semi-analytical solution is derived to consider the effect of fluid viscosity in the elastic deformation regime. Two asymptotes are identified that gives steep pressure gradients near the injection point and near the fracture tip which are also identified in the DLM simulations. Simulations also show three evolving regimes on energy dissipation/transfer mechanisms: the viscosity dominant, the elastic deformation dominant and the mixture of elastic deformation and toughness.

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Montague, James. « Assessing The Probability Of Fluid Migration Caused By Hydraulic Fracturing ; And Investigating Flow And Transport In Porous Media Using Mri ». ScholarWorks @ UVM, 2017. http://scholarworks.uvm.edu/graddis/793.

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Hydraulic fracturing is used to extract oil and natural gas from low permeability formations. The potential of fluids migrating from depth through adjacent wellbores and through the production wellbore was investigated using statistical modeling and predic-tive classifiers. The probability of a hydraulic fracturing well becoming hydraulically connected to an adjacent well in the Marcellus shale of New York was determined to be between 0.00% and 3.45% at the time of the study. This means that the chance of an in-duced fracture from hydraulic fracturing intersecting an existing well is highly dependent on the area of increased permeability caused by fracturing. The chance of intersecting an existing well does not mean that fluid will flow upwards; for upward migration to occur, a pathway must exist and a pressure gradient is required to drive flow, with the exception of gas flow caused by buoyancy. Predictive classifiers were employed on a dataset of wells in Alberta Canada to identify well characteristics most associated to fluid migration along the production well. The models, specifically a random forest, were able to identify pathways better than random guessing with 78% of wells in the data set identified cor-rectly. Magnetic resonance imaging (MRI) was used to visualize and quantify contami-nant transport in a soil column using a full body scanner. T1 quantification was used to determine the concentration of a contaminant surrogate in the form of Magnevist, an MRI contrast agent. Imaging showed a strong impact from density driven convection when the density difference between the two fluids was small (0.3%). MRI also identified a buildup of contrast agent concentration at the interface between a low permeability ground silica and higher permeability AFS 50-70 testing sand when density driven con-vection was eliminated.

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Wang, Yilin. « Simulation of fracture fluid cleanup and its effect on long-term recovery in tight gas reservoirs ». [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3222.

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Liu, Yong [Verfasser], Mohd [Akademischer Betreuer] Amro, Mohd [Gutachter] Amro, Heinz [Gutachter] Konietzky et Xiaoxi [Gutachter] Zhang. « Optimization of fracturing fluid to increase shale gas production / Yong Liu ; Gutachter : Mohd Amro, Heinz Konietzky, Xiaoxi Zhang ; Betreuer : Mohd Amro ». Freiberg : Technische Universität Bergakademie Freiberg, 2020. http://d-nb.info/1226111254/34.

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Khadraoui, Sofiane. « Analyse des impacts environnementaux liés à l'exploitation des réservoirs non conventionnels ». Thesis, Pau, 2022. https://tel.archives-ouvertes.fr/tel-03969353.

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L'objectif de ce travail est d'évaluer les impacts environnementaux liés aux opérations de fracturation hydraulique à travers l'étude des mécanismes d'adsorption des produits chimiques utilisés dans les fluides de fracturation et prédire le devenir de ces additifs injectés dans la roche mère. A travers les résultats obtenus, Il s'avère que la bentonite a un pouvoir très adsorbant du xanthane par rapport aux autres minéraux contenus dans la roche mère. Les trois matrices modèles à savoir la bentonite, la calcite et la kaolinite ont le même pouvoir adsorbant du sp breaker. Il apparaît, aussi, que le xanthane est un produit biodégradable car c'est un biopolymère de fermentation utilisant le xanthomonas campestris, à l'inverse du sp breaker qui est un produit non biodégradable, nécessitant d'autres méthodes de traitement. Ces deux résultats nous ont permis de conclure que la bentonite peut être utilisée comme un adsorbant pour le traitement des eaux de retour afin l'éliminer des deux produits cités précédemment (xanthane et sp breaker) dont les quantités ne sont pas négligeables dans ces eaux (flow back) et qui posent un problème environnemental assez important. Les résultats obtenus à travers l'étude rhéologique ont montré que l'agent gélifiant (xanthane) à tendance à s'épaissir (forte viscosité) quand il est soumis à de faibles contraintes de cisaillement et à se fluidifier (faible viscosité) quand il est soumis à de fortes contraintes de cisaillement. De plus, cet additif présente une viscosité qui augmente avec le temps. Ainsi, les échantillons conservés pendant 24 heures nécessitent plus d'énergie pour être injectés dans le gisement. Le mélange eau-gélifiant se comporte comme un fluide rhéofluidifiant avec l'existence d'une contrainte critique d'écoulement. Cet écoulement n'est observé que lorsque la contrainte de cisaillement appliquée est supérieure à cette valeur critique. Par ailleurs, les essais analytiques, numériques et expérimentaux de fracturation hydraulique réalisés au laboratoire sur un certain nombre d'échantillons cylindriques de PMMA synthétisés nous ont permis de conclure que le débit et la taille des fissures initiales ont plus d'impact que la viscosité sur la pression de rupture. Un accord raisonnable a été obtenu entre les résultats des modèles analytiques et numériques comparés aux données expérimentales (réelles). Comparés aux résultats de l'étude analytique, les résultats de l'étude de simulation numérique sont les plus proches des résultats expérimentaux (réels). Cette bonne corrélation entre les résultats expérimentaux et numériques s'explique par le fait que l'étude analytique ne prend en compte que la profondeur de la fissure, à l'inverse de la simulation numérique, qui prend en considération la forme de la fissure semi-elliptique (demi-longueur et profondeur). Mots clés : schiste, fluide de fracturation roche mère, PMMA
The objective of this work is to evaluate the environmental impacts related to hydraulic fracturing operations by studying the adsorption mechanisms of chemicals additives used in fracturing fluids and to predict the evolution of these additives injected in large quantities into the shale. Based on the results obtained, it appears that bentonite has a high adsorption capacity of xanthan additive compared to other minerals contained in the shale. The three-model matrices bentonite, calcite and kaolinite have the same adsorption capacity of sp breaker additive. It also appears that xanthan is a biodegradable product, unlike sp breaker, which is a non-biodegradable product, requiring other treatment methods other than the biological method. These two results allowed us to conclude that Bentonite can be used as an adsorbent for the treatment of return water for the elimination of the two products (xanthan and sp breaker), both of which are present in significant quantities in the return water (flow back) and present a fairly significant environmental problem. The results obtained by the rheology studies showed that the gelling agent (xanthan) has a high viscosity when applied under low shear stress and a low viscosity when applied under high shear stress. This shear stress tends to increase for the samples conserved for 24 hours and needs more energy to be injected into the shale. The water-gelling agent mixture behaves like a rheofluidifying fluid with a critical flow stress and flow is only observed when the applied shear stress is above this critical value. In addition, analytical, numerical and experimental hydraulic fracturing tests carried out in the laboratory on a number of cylindrical samples of synthesized PMMA showed that the flow rate and the initial crack size has more impact than viscosity on breakdown pressure. A good agreement was obtained between the results of the analytical and numerical models compared to the experimental results. The results of the numerical simulation study are nearly the same as the experimental (real) results compared to the analytical study, because the analytical study only takes into account the depth of the crack, but the numerical simulation, which considers the shape of the semi-elliptical crack (half-length and depth). Key Words: shale, fracturing fluid, source rock, PMMA

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Zeng, Lingping. « Fluid-Shale Geochemical Characterization and Its Relation to Geomechanics : Implications for Low Recovery of Flowback Water during Hydraulic Fracturing in Shale Reservoirs ». Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/83826.

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This study aims to systematically reveal the role of fluid-rock interactions during hydraulic fracturing in shale reservoirs from both geochemical and geomechanical perspectives by conducting comprehensive physicochemical modelling with combination of spontaneous imbibition tests and rock mechanics experiments to understand the impact of fluid-rock interactions on shale wettability, water uptake ability, flowback water chemistry and geomechanical behaviours.

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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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Lefort, Vincent. « Un modèle lattice pour simuler la propagation de fissures sous l’effet d’une injection de fluide dans un milieu hétérogène quasi-fragile ». Thesis, Pau, 2016. http://www.theses.fr/2016PAUU3011/document.

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Cette thèse vise à développer un modèle numérique de type lattice permettant de simuler la propagation de fissures sous l’effet d’une injection de fluide dans un milieu hétérogène quasi-fragile. Si la finalité de l'étude concerne l'étude de matrices rocheuses naturelles, dans les différentes parties du manuscrit détaillée ci-après et dans un souci de validation, le modèle a été régulièrement confronté à des résultats expérimentaux obtenus sur des matériaux cimentaires similaires à des roches naturelles en termes de comportements mécaniques et de transport mais présentant des hétérogénéités mieux contrôlées. La première partie du document est dédiée à l'étude du processus de fissuration caractéristique des matériaux quasi-fragiles présentant une zone d'élaboration. Un outil d'analyse statistique basé sur les fonctions de Ripley et permettant d'extraire une longueur caractéristique à partir d'un nuage de points -- lieux d'un endommagement mécanique -- et présenté. Il est ensuite utilisé dans le cadre d'essais numériques et expérimentaux de rupture par flexion 3 points sur des éprouvettes de bétons. Les résultats montrent que le modèle numérique de type lattice est capable de rendre compte à la fois du processus global de fissuration mais également du processus local de fissuration. Par ailleurs, cet outil permet également de montrer l'influence du mode de sollicitation sur le développement de l'endommagement au sein d'une structure. La deuxième partie du document présente une loi de comportement élasto-plastique endommageable représentative du comportement de joints. L'originalité du modèle réside dans le couplage entre l'endommagement sous sollicitation normale et la plasticité sous sollicitation tangentielle. Cette nouvelle loi permet de reproduire correctement des résultats d'essais de cisaillement indirects effectués sur des joints de plâtre séparant des épontes en mortier alors qu'un modèle de Mohr-Coulomb classique ne le permet pas. La troisième partie est dédiée à l'introduction d'un couplage hydromécanique complet dans le modèle lattice utilisé précédemment. Le couplage hydromécanique est introduit au travers du comportement poromécanique du milieu basé sur une description mécanique-hydraulique duale et intrinsèque du modèle lattice. La contrainte totale fait le lien entre la contrainte mécanique du lattice mécanique et la pression de pore du lattice hydraulique au travers du coefficient du Biot du milieu alors que la perméabilité locale pilotant le gradient de pression hydraulique est indexée sur les ouvertures locales de fissures estimées au travers du lattice mécanique. Les résultats obtenus par ce modèle hydro-mécanique dual ont été confrontés à des solutions analytiques données dans la littérature pour des fissures de type "bi-wings", et il est montré que les deux approches sont cohérentes pour une fissure parfaitement rectiligne. Après les différentes étapes de validation du modèle présentées dans les parties précédentes, la quatrième et dernière partie est dédiée à la simulation numérique du couplage hydromécanique sous-jacent à la propagation libre d'une fissure propageant sous l'effet d'une injection de fluide et de son interaction avec un joint rocheux naturel. Les trajets de fissuration, non maillés a priori, et les profils de pression au sein de la matrice poreuse sont obtenus et comparés en fonction de l'inclinaison du joint rocheux. Par ailleurs, le traitement statistique concernant les lieux d'endommagement développé en première partie est repris ici afin de caractériser l'évolution des longueurs de corrélation entre point s'endommageant au cours de la propagation de la fissure et de son interaction avec le joint. Il est montré que le modèle hydromécanique lattice permet de représenter différent mécanismes de ré-initiation de fissure à partir d'un joint suivant son inclinaison
This research study aims at developing a lattice-type numerical model allowing the simulation of crack propagation under fluid injection in a quasi-brittle heterogeneous medium. This numerical tool will be used to get a better understanding of initiation and propagation conditions of cracks in rock materials presenting natural joints where the coupling between mechanical damage and fluid transfer properties are at stake. If the final goal of the study does concern natural rocks, the model has been validated by different comparisons with experimental results obtained on cementitious materials mimicking natural rocks in term of mechanical and transport behaviours but presenting heterogeneities which are better controlled. The first part of the manuscript presents a general state of the art. The second part of the manuscript is dedicated to the study of crack propagation in quasi-brittle materials where a significant fracture process zone is evolving upon failure. Only the solid phase is studied here and a statistical tool based on Ripley’s functions is adapted in order to extract a characteristic length representative of the correlations appearing between a set of point undergoing mechanical damage. This tool is then used in the context of numerical and experimental fracture tests on 3 point bending concrete beams. The results show that the lattice-type numerical model is able to capture the global fracture process – in term of force vs. crack opening mouth displacement – but also the local fracture process – in term of dissipated energy and correlation length evolution between damage points. Moreover, this statistical tool shows how the solicitation mode may influence the development of damage within a structure. The third part presents a new elasto-plastic damage constitutive law for joint modelling. The originality of the model lies in the coupling between mechanical damage under normal strain and plasticity under tangential strain. This new constitutive law is able to reproduce indirect shear experimental tests performed on mortar specimens presenting a plaster joint where a classical Mohr-Coulomb criterion fails. The fourth part is dedicated to the representation of the full hydro-mechanical coupling within the lattice-type numerical model. The hydro-mechanical coupling is introduced through a poromechanical framework based on the intrinsic and dual hydro-mechanical description of the lattice model, which is based on a "hydraulic" Voronoï tessellation and a "mechanical" Delaunay triangulation. The total stress links the mechanical stress and the pore pressure through the Biot coefficient of the medium whereas the local permeability, which drives the hydraulic pressure gradient, depends on the local crack openings. The numerical results are compared with analytical solutions from the literature for "bi-wings" shape cracks and it is shown that both approaches present similar results for a perfect straight crack. Once the lattice-model has been successfully validated within the former parts of the manuscript, its fifth and last part is dedicated to the numerical simulation of the fully hydro-mechanical coupling problem of a free crack propagation due to fluid injection and its interaction with a natural joint in an heterogeneous rock medium. Different crack paths, which are not pre-meshed a priori, and different pressure profiles are obtained and compared for different joint inclinations. Finally, our statistical tool, which has been primarily developed for the analysis of the failure behaviour of the solid phase, is used to characterise the evolution of correlation lengths between points undergoing damage upon the crack propagation and its interaction with a natural joint. It is shown that the hydro-mechanical lattice model is able to represent different mechanism of crack stop and restart from a joint depending on its inclination

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Lary, Brent Alexander. « Utilizing noble gases to identify hydraulic fracturing “sweet spots” and evaluate the occurrence of carbon isotopic reversals of hydrocarbons within the Northern Appalachian Basin ». The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu15924000841796.

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Touboul, Eric. « Simulation numérique tridimensionnelle d'un problème de fracturation hydraulique ». Ecully, Ecole centrale de Lyon, 1986. http://www.theses.fr/1986ECDL0004.

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On présente ici un modèle numérique de fracturation hydraulique dans un milieu tridimensionnel, base sur un couplage entre : une suite d'états d'équilibre élastique, l'écoulement du fluide à l'intérieur de la fracture, et le phénomène de rupture. Pour l'élasticité, une formulation intégro-variationnelle permet de se ramener à un problème bidimensionnel tout en évitant les singularités classiques. La résolution numérique se fait par éléments finis sur un maillage mobile. On résout d'abord le problème d'équilibre. Les résultats numériques pour l'ouverture et les facteurs d'intensité de contrainte sont en très bon accord avec des solutions analytiques disponibles pour des géométries simples. Puis le couplage et la propagation sont réalisés. Les résultats sont compares a ceux obtenus par des modèles plus simples dans l'industrie pétrolière.

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Soerensen, Dennis Dam. « Optimization and Analysis of The Total Cavo-Pulmonary Connection ». Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10444.

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Single Ventricle congenital heart defects with cyanotic mixing between systemic and pulmonary circulations afflict 2 per 1000 live births. The total cavo-pulmonary connection (TCPC), where the superior and inferior vena cavae are sutured to the left and right pulmonary arteries, is the current procedure of choice. It is believed that reducing the fluid mechanical power losses in the TCPC will relieve strain on the single functional ventricle. It is hypothesized that a proposed idealized TCPC design, decreases power losses to a level below that of any other TCPC designs, while providing other advantages and increased flexibility. Physical models with slightly different geometries of the proposed design were created, and in vitro experiments carried out with particle image velocimetry (PIV), phase contrast magnetic resonance imaging (PC-MRI), and control volume flow analysis at physiological flow rates. Computational fluid dynamics (CFD) was used for numerical studies of the same geometries as in the physical models. Power losses were calculated using the control volume method and the viscous power dissipation function. The latter method incorporated registration of high-resolution PC-MRI velocity vectors to tetrahedral meshes followed by inverse interpolation of the vectors onto the meshes. Detailed flow structures were analyzed. Results show that the new design is more energy efficient than any other idealized models. Furthermore, a tool was developed to extract flow and vessel information from PC-MRI datasets obtained from patients with Fontan connections. The tool utilized a display algorithm, which was developed for optimal noise detection in PC-MRI images. This enabled accurate segmentation. Comparing PC-MRI images before and after this accurate segmentation showed that the standard deviations of the pixels at the perimeter of the segmented vessel were statistically significantly smaller after the segmentation in 94.1% of the datasets investigated. The developed tool was able to extract flow, flow in the quadrants of vessels, area of the segmented vessel, velocities and pulsatility indices. The velocity vectors were exported for use as CFD boundary conditions in models reconstructed from patient anatomies. A database was created with patient PC-MRI data from approximately 140 patients, which is probably the largest database in the world.

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Imbert, Tony. « Caractérisation de la rigidité diélectrique de fluides et d'une roche en fonction de leur conductivité, de la température et de la pression ». Thesis, Pau, 2019. http://www.theses.fr/2019PAUU3036.

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L’urgence énergétique mondiale impose d’utiliser des systèmes plus économes en énergie. De plus, il devient nécessaire d’effectuer une transition énergétique vers des technologies rejetant moins de gaz à effet de serre. Pour ces raisons, les technologies à base de puissances pulsées auront un rôle à jouer dans le panel énergétique de demain.De nombreuses ressources se situent sous la surface de notre planète (eau, gaz, énergies fossiles, minéraux précieux, énergie géothermique ...). De plus, l’urbanisation de nos villes avec le développement des moyens de transport, du traitement des eaux usées, des réseaux électriques et de chaleurs nous pousse à exploiter l’espace sous terrain. Pour cette exploitation, la mise en place de méthodes industrielles est inévitable pour permettre un avancement rapide, économe en énergie et à moindre coût de production. Les méthodes actuelles de concassage, fracturation ou forage se heurtent néanmoins à une faible vitesse de production lors du traitement de roches dures et abrasives. La fracturation dite électrique pourrait être une méthode alternative. Cette technique utilise des décharges électriques dans des fluides pour concasser les roches.L’objet de cette thèse est d’établir une base de données expérimentales pour la compréhension, la prédiction et l’optimisation du processus. Il s’agit plus particulièrement d’étudier l’influence de l’ensemble des paramètres liés à la fois aux propriétés du milieu (température, conductivité et pression) et aux caractéristiques du circuit électrique sur la rigidité diélectrique des isolants testés. Une attention particulière est portée à la maîtrise de la phénoménologie de la décharge dans ces conditions expérimentales.Dans ce manuscrit, les décharges électriques sont caractérisées à partir d’essais expérimentaux qui sont interprétés par l’intermédiaire d’études théoriques et de simulations numériques. Dans un premier temps, la tension minimale nécessaire pour amorcer un arc est déterminée par la méthode U50 et sa consommation d’énergie associée est calculée. Ces essais sont réalisés à la fois en fonction des paramètres internes au système d’impulsions (énergie stockée, tension d’alimentation et géométrie des électrodes) et aussi en fonction de paramètres externes (conductivité, pression et température du milieu). Dans un second temps, le seuil de champ électrique qui permet de changer de mode de claquage est déterminé en fonction des paramètres externes au système d‘impulsions. Cette transition entre le mode subsonique et le mode supersonique est déterminée à partir du temps de propagation de la décharge électrique et de la consommation d’énergie pendant la phase de pré-arc. Les conditions menant à l’amorçage de l’arc électrique dans les fluides ou dans les roches sont comparées. Une attention particulière est donnée à la résistance de l’arc et au courant maximal qui définissent la puissance transmise au milieu
The global energy emergency requires more energy-efficient systems. In addition, it is necessary to make an energy transition to technologies that emit less greenhouse gases. For these reasons, pulse power technologies will have a role to play in tomorrow’s energy mix.Many resources are located below the surface of our planet (water, gas, fossil fuels, precious minerals, geothermal energy...). In addition, the urbanization of our cities with the development of means of transport, wastewater treatment, electricity and heat networks pushes us to exploit the underground space. For this operation, the implementation of industrial methods is inevitable in allowing a fast, energy-efficient and low-cost production. However, current methods of crushing, fracturing or drilling encounter a low production rate when processing hard and abrasive rocks. The fracturing method called electric fracturing could be an alternative method. This method uses electrical discharges in fluids to crush rocks.The purpose of this thesis is to establish an experimental database for understanding, predicting and optimizing the process. In particular, the influence of all parameters related to both the properties of the medium (temperature, conductivity and pressure) and the characteristics of the electrical circuit on the insulators dielectric strength tested must be studied. Particular attention is paid to controlling the phenomenology of the landfill under these experimental conditions.In this manuscript, electrical discharges are characterized on the basis of experimental tests that are interpreted through theoretical studies and numerical simulations. First, the minimum voltage required to initiate an arc is determined by the U50 method and its associated energy consumption is calculated. These tests are performed both according to the internal parameters of the pulse system (stored energy, supply voltage and electrode geometry) and also according to external parameters (conductivity, pressure and temperature of the medium). In a second step, the electric field threshold that allows to change the breakdown mode is determined according to the parameters external to the pulse system. This transition from subsonic to supersonic mode is determined from the propagation time of the electrical discharge and the energy consumption during the pre-arc phase. The conditions leading to the initiation of the electric arc in fluids or rocks are compared. Particular attention is paid to the arc resistance and maximum current that define the power transmitted in the medium

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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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SÁ, BESERRA Leila Brunet de. « Análise hidromecânica do fraturamento hidráulico via elementos finitos com descontinuidades fortes incorporadas ». Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/18305.

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O fraturamento hidráulico é uma técnica amplamente utilizada pela engenharia de petróleo principalmente para aumentar o índice de produtividade ou injetividade dos poços. Essa técnica consiste na injeção de um fluido penetrante na formação, sob uma pressão suficientemente alta para causar a ruptura da rocha, iniciando assim uma fratura que se converte em um canal de alta permeabilidade e facilita o escoamento de hidrocarbonetos. A técnica de fraturamento hidráulico tem sido responsável pela viabilização econômica de muitos campos petrolíferos em todo o mundo e a compreensão dos mecanismos que determinam o fraturamento, bem como a busca de métodos que permitam prever a geometria da fratura induzida e também determinar a pressão de injeção de fluidos necessária para que o fraturamento ocorra, são de fundamental importância para estabelecer um melhor projeto de explotação desses campos. O objetivo principal deste trabalho é desenvolver uma nova metodologia para simular numericamente, de maneira robusta, estável e eficiente, o problema de fraturamento hidráulico em formações rochosas de baixa permeabilidade pelo método dos elementos finitos, usando a aproximação contínua de descontinuidades fortes. Além de propor uma formulação que incorpora o efeito de descontinuidades permeáveis ou impermeáveis no problema de fluxo em meios porosos. A técnica de descontinuidades fortes incorporadas se mostrou eficiente, em relação ao custo computacional, para simular o fraturamento, uma vez que permite discretizar o domínio do problema com malhas relativamente grosseiras e, ainda assim, capturar, adequadamente, o efeito de uma descontinuidade de espessura muito menor do que o tamanho dos elementos da malha. A metodologia desenvolvida neste trabalho foi capaz de simular adequadamente o problema de fraturamento hidráulico em meios contínuos ou em formações rochosas com fraturas naturais preexistentes. E os resultados obtidos contribuem para o melhor entendimento do mecanismo de fraturamento em formações rochosas e a influência dos vários fatores envolvidos no processo.
Hydraulic fracturing is a widely used technique in the petroleum engineering for the generation of a high conductivity channel in the rock formation, increasing the productivity or injectivity index of wells. This technique consists of injecting a fracturing fluid in the rock formation, under a high enough pressure to induce the rock failure. Once started, the fracture is converted into a high permeability channel for the flow of hydrocarbons. The hydraulic fracturing has been in charge of the economic feasibility of many oil fields around the world and understanding the mechanism that determine the fracturing as well as the search for methods to predict the geometry of the induced fracture and also determine the fluid pressure required for the fracturing to occur, are crucial to establish a better exploitation design for these oil fields. The main purpose of this work is to develop a new methodology to numerically simulate, in a robust, stable and efficient way, the hydraulic fracturing problem in low permeability rock formations using the strong discontinuity approach. In addition, it also proposes a formulation that embeds the effect of a permeable or impermeable discontinuity for the fluid flow into the finite element. The technique of embedded strong discontinuities has been proved to be an efficient manner to simulate the fracturing problem, since it allows to discretize the problem domain with relatively coarse meshes and capture, properly, the effect of a discontinuity much thinner than the size of the element. The methodology developed in this work was able to properly simulate the hydraulic fracturing problem in a continuous media or in reservoirs crossed by natural fractures. The results obtained have contributed to a better understanding of the fracturing mechanism in rocks and the influence of the numerous involver factors.

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Zanella, Alain. « Surpression de fluides et fracturation de roches mères en différents contextes tectoniques : modélisation analogique et exemples de terrain ». Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00980281.

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L'étude des surpressions de fluide et de fracturation hydraulique des roches mères peut nous renseigner sur les mécanismes de génération qui en sont à l'origine. Ces dernières années, l'intérêt pour ces phénomènes s'est largement accru, notamment sous l'influence des sociétés pétrolières qui exploitent les ressources non-conventionnelles au cœur des problèmes énergétiques actuels. Dans ce travail de thèse, nous avons choisi deux approches différentes pour l'étude de ces mécanismes : (1) des exemples de cas géologiques naturels, et (2) le développement de la modélisation analogique. Ainsi, nous montrons que ces phénomènes sont très répandus au sein des bassins sédimentaires et que leurs manifestations s'expriment notamment par la génération de veines fibreuses parallèles à la stratification de la roche (beef), mais également par la formation de veines d'hydrocarbures solides (bitume). Nous démontrons également que les surpressions de fluides peuvent profondément changer le style de déformation d'un bassin sédimentaire par la génération de niveaux de décollement localisés au sein même des roches mères. Enfin, à l'aide de la modélisation analogique, nous avons pu identifier les mécanismes à l'origine des surpressions de fluide et de la fracturation hydraulique. En effet, lors de la génération d'hydrocarbures la transformation de solide à liquide de la matière organique conduit à la compaction chimique des sédiments. Par un mécanisme de transfert de charge lors de ce processus, ainsi que par l'accroissement de volume associé, des surpressions de fluides se développent et atteignent des pressions lithostatiques, capables de fracturer hydrauliquement les roches.

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Loiseau, Philippe. « Etude structurale et geostatistique des gneiss de la region du cezallier : modelisation tridimensionnelle de reseaux de fractures, application a l'ecoulement des fluides ». Orléans, 1987. http://www.theses.fr/1987ORLE2055.

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L'etat de fracturation d'un massif cristallin par l'intermediaire de la modelisation est apprehende et passe par des etapes d'acquisition des donnees qui se font en surface et en profondeur, ainsi que par des etapes d'analyse suivant le parametre choisi. L'hydrogeologie des milieux fissures et l'une des applications aux modelisations de champs de fracture. On peut ainsi mettre en evidence un comportement discontinu du flux

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Crognier, Nemo. « Evolution thermique, circulation de fluide et fracturation associées à la structuration du bassin d’avant-pays sud-pyrénéen ». Thesis, Pau, 2016. http://www.theses.fr/2016PAUU3030/document.

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Le bassin de Jaca (Pyrénées espagnoles) est un exemple classique de bassins d’avant pays, où les grandes lignes du remplissage sédimentaire, ainsi que la chronologie des failles ont été très étudiées. Il reste toutefois à mieux comprendre la paléo-hydrologie et l’histoire thermique du bassin, de manière à proposer un modèle de circulation des fluides pendant sa mise en place et sa déformation (Paléocène-Oligocène). Pour ce faire, ce travail propose d’analyser la répartition de la fracturation, d’étudier les conditions de formation des veines syn-tectoniques et de caractériser la maturité de la matière organique sur l’ensemble du paléobassin d’avant-pays de Jaca, des zones internes vers les zones externes.L’analyse pétrographique, géochimique et microthermométrique des veines montre que la grande majorité des fluides minéralisateurs sont à l’équilibre isotopique et thermique avec l’encaissant. Dans le détail, nous avons identifié 2 événements principaux de formation de veines dans la zone interne du bassin (Sierras Interiores), que nous proposons d’associer au fonctionnement des failles majeures dans le socle. Nous suggérons que les fluides circulent le long des niveaux de décollements et sont expulsés sur de courtes distances (< 10 km), au travers des réseaux de fractures, vers le bassin d’avant-pays. Le reste du bassin enregistre principalement des fluides locaux, parfois associés à l’infiltration d’eau météorique. L’analyse des températures d’enfouissement (50°C à 250°C), qui inclut des données de Δ47, montre une organisation N-S relativement homogène depuis les Sierras Interiores (fenêtre à gaz) jusqu’aux Sierras Exteriores (immature), avec des anomalies longitudinales marquées. Les modélisations thermiques 1D sur 9 puits virtuels suggèrent que les températures maximales vers les Sierras Interiores peuvent résulter d’un enfouissement sédimentaire, dont une grande partie est érodée actuellement. Nous proposons que ces parties érodées correspondent à des dépôts tardi-orogéniques conglomératiques déposés à proximité de la zone axiale. Les données suggèrent une répartition non homogène de ces dépôts selon un axe E-W, impliquant des transferts sédimentaires plus complexes qu’habituellement discutés. Au vu de nos résultats et des précédentes études, le modèle paléohydrologique et thermique du bassin de Jaca, et à plus grande échelle, de la chaîne plissée sud-pyrénéenne, est compartimenté à la fois dans l’espace et dans le temps, en lien avec à la propagation latérale et frontale de la déformation, qui contrôle l’ouverture du système. Le modèle paléohydrologique et thermique de la chaîne plissée sud-pyrénéenne constitue donc un potentiel analogue aux chaînes plissées dont le raccourcissement résulte d’une convergence oblique
The Jaca basin (Spanish Pyrenees) is a classical example of a foreland basin, where the sedimentary filling and the calendar of thrust activation have been extensively studied. It remains to understand the paleohydrology and the thermal history of the basin, so as to provide a fluid flow model related to its formation and deformation (Paleoecene-Oligocene). To do this, this work proposes to analyze the distribution of fracturing, to study the conditions of formation of syn-tectonic veins and to characterize the maturity of organic matter throughout the Jaca foreland basin, from hinterland to external areas.Petrographical, geochemical and microthermometric analysis of veins show that the vast majority of mineralizing fluids are at the isotopic and thermal equilibrium with the host-rock. In detail, we identified two main events of vein precipitation in the inner part of the basin (Sierras Interiores), probably related to major basement thrust activations. We suggest that fluids flow along decollement levels and are expelled over short distances (<10 km), through fracture networks towards the foreland basin. The other part of the basin mainly record local fluids, sometimes associated with the infiltration of meteoric water. Analysis of burial temperatures (50 °C to 250 °C), which includes Δ47 data, shows a relatively homogeneous N-S organization from the Sierras Interiores (gas window) to Sierras Exteriores (immature), with strong longitudinal anomalies. Thermal 1D modelling of 9 virtual wells suggest that the maximum temperatures of Sierras Interiores result from sedimentary accumulation, whose a large amount is now eroded. We propose that this eroded thickness corresponds to late-orogenic conglomeratic deposits near the axial zone. The data suggest an inhomogeneous distribution of the deposits along an E-W axis, involving more complex sedimentary transfers than usually discussed. Given our results and previous studies, the paleohydrological and thermal model of the Jaca basin, and on a larger scale, of the South Pyrenean fold and thrust belt, is compartmentalized both in space and in time, in response to the propagation of and oblique deformational front, which controls the opening of the system. The paleohydrological and thermal model of the South Pyrenean fold and thrust belt is therefore a potential analogue to fold and thrust belt including shortening due to an oblique convergence

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Ndongo, Alexis. « Contexte sédimentologique et tectonique du bassin paléoprotérozoïque de Franceville (Gabon) : structures de surpression fluide, bitumes et minéralisation uranium ». Thesis, Dijon, 2016. http://www.theses.fr/2016DIJOS068/document.

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La formation des gisements métallogéniques en général et uranifères en particulier, dans les bassins paléoprotérozoïques, dépend de la migration des fluides riches en divers éléments (U, Cu, Fe, etc.). L’objet de cette thèse a été de définir le contexte tectonique, sédimentologique et diagénétique associées aux gisements bitume--‐uranium du bassin de Franceville. L’étude tectonique réalisée met en évidence des failles de transfert N180--‐170, héritées de la tectonique archéenne et des failles normales longitudinales N110--‐120. Ces deux familles de failles compartimentent le bassin de Franceville en plusieurs sous--‐bassins de subsidence variable. Les failles longitudinales N110--‐120° contrôlent la mise en place d’anticlinaux de mur et des synclinaux de toit synsédimentaires (i.e. discordances progressives). Les gisements d’uranium du bassin de Franceville, se localisent au niveau des anticlinaux de mur des failles normales. L’étude sédimentologique du bassin caractérise la distribution spatiale des paléoenvironnements de dépôt. Quatre grands environnements de dépôts sont respectivement mis en évidence : fluviatile (formation FA inferieur), deltaïque (formation FA moyen), tidal (formation FA Supérieur) et marin profond (formation FB). La distribution des facies sédimentaires à la transition FA--‐FB est responsable de la mise en place de barrières de perméabilité. Les barrières de perméabilité sont responsables de l’augmentation de la pression fluide, qui favorise la mise en place des structures de surpression fluide (dykes, stylolites, veines de quartz), au voisinage des anticlinaux de mur contrôlés par les failles normales. Les différences de pression dans le bassin favorisent la migration des fluides uranifères et des hydrocarbures, des zones profondes du bassin vers les anticlinaux de mur. Les structures de fracturation hydraulique vont contrôler la mise en place des bitumes et des minéralisations d’uranium associées
Metallogenic deposits within paleproterozoic basins depend on generation and migration of fluids. The aim of this study is to provide a better understanding of tectonic, sedimentological and diagenetic setting of the uranium deposits in the Franceville basin and to characterize hydraulic fracturing impact on fluid migration processes in sandstone reservoirs.Tectonic study define the N180-170° transfer faults, associated with Archean tectonic and the N110-120° longitudinal normal faults. These two fault directions split the Franceville basin into small sub-basins. The longitudinal normal faults are associated with footwall anticlines and hanging wall synclines. The uranium deposits of Franceville basin are located in footwall anticlines of longitudinal normal faults.Sedimentological analysis allows to describe four depositional environments: Fluvial (lower FA), deltaic (middle FA), tidal (upper FA), and open marine environments (FB). Facies distribution in the FA-FB transition promotes the establishment of permeability barriers. These latter are responsible of the increase in fluid pressure and of the formation of fluid pressure structures (dykes, stylolites, quartz veins), in footwall anticlines of longitudinal normal faults. Increase in fluid pressure allows the migration of uranium-fluids, and hydrocarbon from the deep basin to the footwall anticline. Hydraulic fracturing processes lead the precipitation of uranium mineralization, associated with bitumen, in microfractures

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Leclere, Bruno. « Endommagement induit par cristallisation dans les conditions de réservoirs géologiques ». Thesis, Pau, 2021. http://www.theses.fr/2021PAUU3004.

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En contexte de réservoirs géologiques, les veines sont des fractures dans lesquels des espèces chimiques ont précipité et qui ont été longtemps associées avec le modèle de ‘fissuration-minéralisation’. Cependant, certaines veines présentent des caractéristiques laissant penser que la précipitation provoquerait la fissuration en s’appuyant sur le concept de pression de cristallisation. En partant de là, deux expériences ont été développées. Pour commencer, nous avons fait précipiter un front de barytine, par diffusion de deux solutions respectivement enrichies en baryum et sulfate à travers deux milieux poreux : un calcaire de Lavoux et un grès des Vosges contenant une fraction d’argile. Le front de barytine précipité a été investigué par l’acquisition de donnés de micro tomographie rayon X, de la microscopie optique et à balayage électronique et de la spectroscopie rayon X. En pratique, aucun endommagement n’a été détecté mais la barytine a nucléé et précipité en relation avec la distribution des pores, l’état de cristallisation des minéraux de la matrice et la présence des complexes argileux. On suspecte une augmentation de volume en lien avec ce dernier point. L’étude de l’endommagement des sels dans le contexte de la préservation des monuments historiques est à la base de notre deuxième expérience réalisée sous un confinement isotrope dans une cellule triaxial du laboratoire de géologie de l’école normale supérieur de Paris. Un front de sulfate de sodium ou de sulfate de magnésium déshydraté est préalablement précipité dans un grès des Vosges et réhydraté pendant l’expérience par imbibition capillaire d’eau milli-Q. De l’endommagement a été mesuré jusqu’à une pression de 27 MPa par l’acquisition d’émissions acoustiques, la propagation d’onde élastique, des jauges de déformation et données de micro tomographie rayons X. Ces experiences montrent une compétition entre la cimentation par le sel du milieu poreux et l'endommagement par crystallisation. Ceci est confirmé par la modélisation des propriétés mécaniques du milieu poreux saturé en sel lors de son hydratation
Veins in geological reservoir settings are mineral-filled fractured long being associ- ated with the model of ‘crack seal’. However, some veins exhibit features that do not match with the model of ‘crack seal’ but would better fit with a ‘seal-crack’ model driven by the concept of crystallisation pressure. From this, two main experimental tests are conducted. We start with an experiment of counter diffusion to precipitate a barite front in an oolite limestone, the Lavoux limestone, and a sandstone with a shale fraction, the Adamswiller sandstone. The reacted samples are analysed via 3D X-ray microtomography, microscopy and SEM-EDS microanalysis. Although we do not ob- serve damage, we show that barite nucleation and crystallisation is linked to the pore distribution and the matrix mineral. In particular, barium interacts with clay min- erals like the smectite-chlorite complex. Ultimately, this interaction may expand the complex basal space when barite precipitates. Then salt studies for the understanding of damage induced on cultural heritage are the starting point of a new protocol with Na2SO4 and MgSO4 to be tested under isotropic confining pressure inside a triaxial cell (ENS Paris). It consists of precipitating an anhydrous salt layer in an Adamswiller sandstone. Later the anhydrous salt layer is rewetted to precipitate a more hydrated salt phase. The damage is monitored at a confining pressure up to 27 MPa with acous- tic emission, elastic wave propagation, strain gauges and 3D X-ray microtomography. These experiments emphasize the competition between salt cementation of the porous medium and salt crystallisation induced damage. The last point is confirmed by the ef- fective modeling of the elastic properties of a porous medium impregnated with sodium sulphate when it is rewetted without confining pressure

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Ribeiro, Lionel Herve Noel. « Multi-phase fluid-loss properties and return permeability of energized fracturing fluids ». Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-05-5443.

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With the growing interest in low-permeability gas plays, foam fracturing fluids are now well established as a viable alternative to traditional fracturing fluids. Present practices in energized fracturing treatments remain nonetheless rudimentary in comparison to other fracturing fluid technologies because of our limited understanding of multi-phase fluid-loss and phase behavior occurring in these complex fluids. This report assesses the fluid-loss benefits introduced by energizing the fracturing fluid. A new laboratory apparatus has been specifically designed and built for measuring the leak-off rates for both gas and liquid phases under dynamic fluid-loss conditions. This report provides experimental leak-off results for linear guar gels and for N2-guar foam-based fracturing fluids under a wide range of fracturing conditions. In particular, the effects of the rock permeability, the foam quality, and the pressure drop are investigated. Analysis of dynamic leak-off data provide an understanding of the complex mechanisms of viscous invasion and filter-cake formation occurring at the pore-scale. This study presents data supporting the superior fluid-loss behavior of foams, which exhibit minor liquid invasion and limited damage. It also shows direct measurements of the ability of the gas component to leak-off into the invaded zone, thereby increasing the gas saturation around the fracture and enhancing the gas productivity during flowback. Our conclusions not only confirm, but add to the findings of McGowen and Vitthal (1996) for linear gels, and the findings of Harris (1985) for nitrogen foams.
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Al, Tammar Murtadha Jawad. « Production performance evaluation of energized fracturing fluids in unconventional formations ». Thesis, 2014. http://hdl.handle.net/2152/28299.

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Pursuit of unconventional gas and oil has prompted the development and adoption of innovative fracturing solutions. Energized fracturing is one promising technology that can be an effective alternative to mainstream slickwater or hybrid fracturing fluids in many applications. Yet, field use of energized fluids accounted for only 2-3% of 2011-2012 reported fracturing treatments in the U.S. compared to a markedly higher share of 42-46% in Canada. Recently, the superior performance and economics of foams were reported in the Montney Gas Formation in western Canada. In this thesis, we utilized field data and a compositional, 3D fracturing simulator to showcase the production performance of energized fluids in several areas of the Cardium and Bakken Light Oil Formations within the Western Canadian Sedimentary Basin. Average well data in the Cardium revealed better production results for foam compared to nitrified slickwater in the West Willesden Green and Buck Lake-Wilson Creek fields. Foams had a 110% higher initial peak production rate and 51% higher long term cumulative production in the West Willesden Green field with a similar initial production profile and a 16.2% higher long-term production in the Buck Lake-Wilson Creek fields. In contrast, the initial peak production rate of nitrified slickwater was 28% higher with 95% incremental oil production relative to foam in the West Pembina field. This shows that the effectiveness of foam fracturing fluids can vary significantly perhaps because of better fracture containment and lower rock water sensitivity in some fields. Across all the areas studied, foam completions on average were found to have 5-20% lower costs and lower water and proppant requirements by 72-87% and 7-38%, respectively. Fracture modeling, on the other hand, showed 53% higher well productivity increase using nitrified slickwater largely because of better contained fractures in the thin Cardium reservoir interval. Nitrified slickwater had twice the propped fracture length and conductivity of foam. With markedly improved fracture containment in depleted Cardium wells, foam is likely to outperform nitrified slickwater as fracturing fluid recovery is enhanced and permeability/relative permeability damage is reduced in water sensitive areas. In the Bakken Formation, field data showed an average of 15.8% higher long term cumulative production for foam compared to crosslinked gel despite the higher initial rate of crosslinked gel. Foam fractures were predicted to have 44% higher well productivity increase than crosslinked gel fractures based on simulations conducted. Foam had 50% longer propped fracture, 73% higher fracture conductivity, and twice the relative permeability to oil in the invaded zone compared to crosslinked gel. In our simulation, some factors were not accounted for such as formation heterogeneity, the effect of solution gas drive and associated water production, and the interaction between induced and natural fractures. Also, our modeling work was based on generic and synthesized data. For more accurate comparisons, we recommend performing simulation runs with detailed well-specific data.
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Ribeiro, Lionel Herve Noel. « Development of a three-dimensional compositional hydraulic fracturing simulator for energized fluids ». 2013. http://hdl.handle.net/2152/22805.

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Current practices in energized treatments, using gases and foams, remain rudimentary in comparison to other fracturing fluid technologies. None of the available 3D fracturing models for incompressible water-based fluids have been able to capture the thermal and compositional effects that are important when using energized fluids, as their constitutive equations assume single-phase, single-component, incompressible fluid flow. These models introduce a bias in fluid selection because they do not accurately capture the unique behavior of energized fluids. The lack of modeling tools specifically suited for these fluids has hindered their design and field implementation. This work uses a fully compositional 3D fracturing model to answer some of the questions surrounding the design of energized treatments. The new model is capable of handling any multi-component mixture of fluids and chemicals. Changes in fluid density, composition, and temperature are predicted using an energy balance equation and an equation of state. A wellbore model, which relates the surface and bottomhole conditions, determines the pumping requirements. Fracture performance is assessed by a fractured well productivity model that accounts for damage in the invaded zone and finite fracture conductivity. The combination of the fracture, productivity, and wellbore models forms a standalone simulator that is suitable for designing and optimizing energized treatments. The simulator offers a wide range of capabilities, making it suitable for many different applications ranging from hydraulic fracturing to long-term injections for enhanced oil recovery, well clean-up, or carbon sequestration purposes. The model is applicable to any well configuration: vertical, deviated, or horizontal. The resolution of the full 3D elasticity problem enables us to propagate the fracture across multiple layers, where height growth is controlled by the vertical distribution of the minimum horizontal stress. We conducted several sensitivity studies to compare the fracture propagation, productivity, and pumping requirements of various fluid candidates in different reservoirs. The results show that good proppant placement and high fracture conductivities can be achieved with foams and gelled fluid formulations. Foams provide a wide range of viscosities without using excessive amounts of gelling agents. They also provide superior fluid-loss control, as the filter-cake is supplemented by the presence of gas bubbles that reduce liquid-flow into the porous medium. CO₂, LPG, and N₂ expand significantly (by 15% or more) as the reservoir heats the fluid inside the fracture. These fluids show virtually no damage in the invaded zone, which is a significant improvement upon water-based fluids in reservoirs that are prone to water blocking. These results, however, are contingent on an accurate fluid characterization supported by experimental data; therefore, our work advocates for complementary experimental studies on fluid rheology, proppant transport, and fluid leak-off. A comprehensive sensitivity study over a wide range of reservoir conditions identified five key reservoir parameters for fluid selection: relative permeability curve, initial gas saturation, reservoir pressure, changes to rock mechanical properties, and water-sensitivity. Because energized fluids provide similar rheology and leak-off behaviors as water-based fluids, the primary design question it to evaluate the extent of the damaged zone against costs, fluid availability, and/or safety hazards. If the fluid-induced damage is acceptable, water-based fluids constitute a simple and attractive solution; otherwise, energized fluids are recommended. Notably, energized fluids are well-suited for reservoirs that are depleted, under-saturated, and/or water-sensitive. These fluids are also favorable in areas with a limited water supply. As water resources become constrained in many areas, reducing the water footprint and the environmental impact is of paramount concern, thereby making the use of energized treatments particularly attractive to replace or subsidize water in the fracturing process.
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Warner, Nathaniel Richard. « Tracing hydraulic fracturing fluids and formation brines using boron, radium, and strontium isotopes ». Diss., 2013. http://hdl.handle.net/10161/8039.

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Production of oil and gas from unconventional natural gas reservoirs such as impermeable organic-rich shale formations was made possible through the use of horizontal drilling and high volume slick water hydraulic fracturing (HVHF). This combination of technologies has changed the energy landscape in the Unites States and possibly provided a vast new energy source from multiple sedimentary basins in the United States (Kargbo et al., 2010; Kerr, 2010) (Figure 1). HVHF requires large volumes of water (~5 million gallons/well) (Lutz et al., 2013) injected under high pressure to stimulate methane release from the fracture systems in the shale formations. The process is conducted within low-permeability formations, which include organic-rich shale rocks that are often the source rock for overlying conventional oil and gas reservoirs but do not easily transport gas to the well bore without stimulation. Once the permeability of the target formation is increased to a level that oil and gas can be recovered, pressure is released and 20-30% of the fluid that was injected flows back up to the surface through the well (Lutz et al., 2013). The remaining 70% stays underground, either lost to adjacent formations or imbed within the formation itself.

While HVHF operations rapidly expanded in many shale plays (e.g., Marcellus, Fayetteville), the possible negative environmental impacts remained un-quantified but a debated topic (Howarth et al., 2011). This dissertation focuses on quantification and evaluation of several water resources for evidence of contamination from HVHF. My hypotheses are: (1) HVHF have distinctive chemical and isotopic fingerprints that are different from other potential contamination sources; and (2) these fingerprints could be identified in aquifers and surface water systems.

I tested these hypotheses in two shallow drinking water aquifers overlying current unconventional gas development, northeastern Pennsylvania and north-central Arkansas, and one area of surface water disposal in western Pennsylvania. I used specific geochemical (Br, Cl, SO4, Na, Ca, Mg, Ba, Sr, B, and Li) and isotopic (87Sr/86Sr, 2H/H, 18O/16O, δ11B, and 228Ra/ 226Ra) tracers to characterize the target-formation brines and delineate possible contamination. The combined geochemical fingerprint distinguished hydraulic fracturing fluids and brines from other types of contamination that could influence water quality (e.g., road salt, sewage, acid mine drainage).

In Pennsylvania (Chapter 1), geochemical and isotopic data shows no direct evidence of contamination in shallow drinking-water aquifers associated with natural gas extraction of the Marcellus Formation. The data instead demonstrated that brine with the same geochemical (Br/Cl, Sr/Cl, and Ba/Cl) and isotopic fingerprint (87Sr/86Sr) of the Marcellus brine was likely naturally present in the shallow formations prior to the most recent oil and gas development. The data indicates that there may be areas in northeastern Pennsylvania that may be at increased risk of contamination from HVHF because of the presence of natural pathways that connect the shallow drinking water aquifers with deeper formations. This Chapter was published in Proceedings of the National Academy of Sciences in July 2012.

A very different result was observed in Arkansas (Chapter 2). While the shallow groundwater data indicated that there was no direct evidence of contamination, there was also no indication of hydrodynamic connections between the deeper formation brine and the shallow aquifers. Indeed 87Sr/86Sr, δ11B, 18O, and 2H values exclude Fayetteville Formation water as a source of salinity in shallow aquifers in the study area. The combined studies indicate that site and basin-specific studies of groundwater quality are necessary in order to evaluate the potential for contamination from HVHF. The Chapter was published in Applied Geochemistry in May 2013.

Surface water disposal of hydraulic fracturing fluids and brines (Chapter 3) clearly impacted western Pennsylvania sediment and water quality. Sediments in the stream at the point of effluent discharge from a treatment facility indicate radium activities 200 times higher than any background values. The 228Ra/226Ra ratios in the sediments also indicate that the source of contamination is likely the recent treatment and disposal of Marcellus brine. Impacts were also observed farther downstream. The concentrations of bromide and chloride in the effluent were so high that an increase in the concentrations measured in the stream was elevated almost two kilometers downstream. Chapter 3 was submitted to Environmental Science and Technology in May 2013.

Overall, this thesis aims to establish inorganic geochemical and isotopic tools for identification of hydraulic fracturing fluids in the environment and assess their possible impact on both surface and groundwater resources.

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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.
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Correa, Castro Juan. « Evaluation and Effect of Fracturing Fluids on Fracture Conductivity in Tight Gas Reservoirs Using Dynamic Fracture Conductivity Test ». Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9106.

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Unconventional gas has become an important resource to help meet our future energy demands. Although plentiful, it is difficult to produce this resource, when locked in a massive sedimentary formation. Among all unconventional gas resources, tight gas sands represent a big fraction and are often characterized by very low porosity and permeability associated with their producing formations, resulting in extremely low production rate. The low flow properties and the recovery factors of these sands make necessary continuous efforts to reduce costs and improve efficiency in all aspects of drilling, completion and production techniques. Many of the recent improvements have been in well completions and hydraulic fracturing. Thus, the main goal of a hydraulic fracture is to create a long, highly conductive fracture to facilitate the gas flow from the reservoir to the wellbore to obtain commercial production rates. Fracture conductivity depends on several factors, such as like the damage created by the gel during the treatment and the gel clean-up after the treatment. This research is focused on predicting more accurately the fracture conductivity, the gel damage created in fractures, and the fracture cleanup after a hydraulic fracture treatment under certain pressure and temperature conditions. Parameters that alter fracture conductivity, such as polymer concentration, breaker concentration and gas flow rate, are also examined in this study. A series of experiments, using a procedure of “dynamical fracture conductivity test”, were carried out. This procedure simulates the proppant/frac fluid slurries flow into the fractures in a low-permeability rock, as it occurs in the field, using different combinations of polymer and breaker concentrations under reservoirs conditions. The result of this study provides the basis to optimize the fracturing fluids and the polymer loading at different reservoir conditions, which may result in a clean and conductive fracture. Success in improving this process will help to decrease capital expenditures and increase the production in unconventional tight gas reservoirs.

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Awoleke, Obadare O. « Dynamic Fracture Conductivity—An Experimental Investigation Based on Factorial Analysis ». Thesis, 2013. http://hdl.handle.net/1969.1/149287.

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This work is about fracture conductivity; how to measure and model it based on experimental data. It is also about how to determine the relative importance of the factors that affect its magnitude and how to predict its magnitude based on these factors. We dynamically placed the slurry hereby simulating the slurry placement procedure in a field-scale fracture. We also used factorial and fractional factorial designs as the basis of our experimental investigation. The analysis and interpretation of experimental results take into account the stochastic nature of the process. We found that the relative importance of the investigated factors is dependent on the presence of outliers and how they are handled. Based on our investigation we concluded that the investigated factors arranged in order of decreasing impact on conductivity are: closure stress, polymer loading, flow back rate, presence of breaker, temperature and proppant concentration. In particular, we find that at high temperatures, fracture conductivity was severely reduced due to the formation of a dense proppant-polymer cake. Also, dehydration of the residual gel in the fracture at high flow back rates appears to cause severe damage to conductivity at higher temperatures. This represents a new way of thinking about the fracture cleanup process; not only as a displacement process, but also as a displacement and evaporative process. In engineering practice, this implies that aggressive flow back schemes are not necessarily beneficial for conductivity development. Also, we find that at low proppant concentrations, there is the increased likelihood of the formation of channels and high porosity fractures resulting in high fracture conductivities. The uniqueness of this work is a focus on the development of a conductivity model using regression analysis and also the illustration of a procedure that can be used to develop a conductivity model using dimensional analysis. We reviewed both methodologies and applied them to the challenge of modeling fracture conductivity from experimental studies.

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Thèses sur le sujet « Fracturing fluids »

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