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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
341

Proteiny slin flebotomů a imunitní aspekty přenosu leishmaniózy / Salivary proteins of sand flies and the immune aspects of Leishmania transmission

Vlková, Michaela January 2013 (has links)
Sand flies serve as the vectors of leishmaniasis and their saliva was shown to affect the outcome of Leishmania infection by immunomodulation of the host. On the other hand, sand fly saliva contains a large scale of farmacologically active proteins that are strongly immunogenous for bitten hosts and specific anti-saliva immunity initiated by repeated sand fly feeding provides protection against Leishmania infection. Specific cell-mediated immunity was shown to be the core of the protectivity; however, our data suggests that the protective immunity has certain limitations. In mice bitten by sand flies for prolonged periods, we observed the desenzitization in term of abrogation of the protective immunity. Thus, we can speculate that the protective effect of immunity is linked solely with the short-term exposure. Nevertheless, our experiments showed that this aspect is also conditioned by the immediate infection after the protective short-term immunization. Taken together, it seems that these limitations may explain the circulation of leishmaniasis in endemic areas, even though humans and animals are frequently immunized by bites of uninfected sand flies. Repeated sand fly feeding on various hosts also promotes production of anti-saliva antibodies that reflect the intensity of exposure. We...
342

[en] AN EXPERIMENTAL STUDY USED IN X-RAY TOMOGRAPHY WITH MECHANISMS ASSOCIATED THE SAND PRODUCTION IN OIL WEELS / [pt] UM ESTUDO EXPERIMENTAL UTILIZADO EM TOMOGRAFIA DE RAIO-X COM MECANISMOS ASSOCIADOS A PRODUÇÃO DE AREIA EM POÇOS DE PETRÓLEO

ALDENIR COSTA 21 May 2007 (has links)
[pt] Freqüentemente, durante os estágios de produção de um poço de óleo, ocorre a produção simultânea de partículas sólidas que originam da massa rochosa ao redor, um processo chamado de produção de areia. Concentrações de tensões nas vizinhanças do poço podem causar perda de coesão entre os grãos, criando assim uma região de matéria granular solta suscetível a ser arrastada pela força de infiltrações. Este trabalho se baseia no estudo da formação de danos nas vizinhanças do poço. Este programa experimental é conduzido ao simular, do interior de uma célula especialmente construída, as pressões crescentes durante esses estágios de escavação numa amostra de rocha, geralmente arenito, pouco consolidada ou um material montado artificialmente simulando arenito. Este processo é conduzido em tempo real dentro de tomógrafo computadorizado de Raio X. Os ensaios tiveram por objetivo identificar a pressão de início e o modo de propagação da ruptura da parede da cavidade interna da amostra ensaiada. Estes são estágios iniciais dos processos de produção de areia em rochas. As análises das imagens tomográficas adquiridas durante os ensaios permitiram a visualização de breakouts e arrombamentos dos poços. Estudos mais detalhados possibilitaram estimar a quantidade de areia produzida e reconstruir tridimensionalmente o processo de propagação de ruptura. / [en] Frequently, during the production stages of an oil well, simultaneous production of solid particles originating from the surrounding rock mass occur, a process called sand production. Stress concentrations around of the well may cause loss of cohesion between grains, thus creating a region of loose granular matter susceptible for drag bye seepage forces. The present work reports on the study of the formation of breakouts/damage around of the well. This experimental program is carried out by simulating, inside an especially constructed cell, the stresses arising during these excavation stages on a sample of a rock, generally a poorly consolidated sandstone or an artificially assembled material simulating a sandstone. This process is carried out in real time inside an X ray computerized tomography. The tests investigated the initial and the evolution of failure at the cavity wall of samples. These are initial stages of the sand production process. The analysis of the CT-scans obtained during tests allowed the visualization of breakouts and collapses of the wells. From studies more details were possible estimate the sand production and produce 3-D images of the propagation of the failure.
343

[en] ANALYSIS OF INSTABILITY OF OIL WELLS ASSOCIATED WITH THE SAND PRODUCTION THROUGH A MODEL OF THE COSSERAT CONTINUUM / [pt] ANÁLISE DA INSTABILIDADE DE POÇOS DE PETRÓLEO ASSOCIADA À PRODUÇÃO DE AREIA ATRAVÉS DE UM MODELO DO CONTÍNUO DE COSSERAT

ANGELA ROCIO BAYONA MENDOZA 10 March 2004 (has links)
[pt] A produção de areia é um dos mais freqüentes e graves problemas observados durante a produção de um poço de petróleo, completado em arenitos mal consolidados. Este fenômeno pode causar obstrução do poço, abrasão dos equipamentos de elevação e de superfície, colapso do revestimento e problemas ambientais derivados da disposição em superfície das areias contaminadas. Por outro lado, em reservatórios de baixa produtividade que produzem óleo de alta viscosidade, uma limitada produção de areia incrementa a produtividade do poço. Nos estudos para previsão da produção de areia é de fundamental importância definir-se um modelo constitutivo capaz de reproduzir o comportamento tensão-deformação do arenito e os mecanismos de ruptura que provocam instabilidade do poço. Este é o tema central desta tese. Em especial, o trabalho procurou explorar modelos constitutivos baseados em meios contínuos de Cosserat. Uma justificativa para isto está relacionada ao fato de experimentos demonstrarem a influência da microestrutura nos processos de ruptura que ocorrem na vizinhança do poço. O modelo utilizado foi o elastoplástico de Bogdanova-Bontcheva & Lippmann (1975) incorporando as leis de fluxo associada e não associada. Inicialmente são definidos alguns conceitos básicos relevantes ao entendimento do fenômeno de produção de sólidos. Uma revisão da teoria dos meios contínuos generalizados de Cosserat é apresentada e em seguida é discutido o modelo elastoplástico de Bogdanova- Bontcheva e Lippmann com detalhes das implementações computacionais necessárias. Finalmente, são feitas análises de geometrias de poços, procurando-se identificar os mecanismos de ruptura que provocam instabilidade e que são uma potencial fonte de produção de areia. / [en] Sand production is one of the most frequent and serious problems observed during the production of an oil well completed in weak sandstones. This phenomenon can cause wellbore plugging, surface and rise equipment abrasion, casing collapse and environmental problems derived from the disposal in surface of contaminated sands. On the other hand, for reservoirs of low productivity, that produce oil of high viscosity, a limited sand production increase the productivity of the well. In the studies for sand production prediction, it is of basic importance to define a consitutive model capable of reproducing the stress-strain behaviour of the sandstones and the failure mechanisms that causes wellbore instability. This is the central focus of the present work. In order to represent the behaviour of the rock masses, models based in Cosserat continuum were used. Elastoplastic models (associated/not associated) under that theory (Bogdanova-Bontcheva and Lippmann) were implemented. Initially, basic concepts related to the understanding of the phenomenon of solid production are presented. A review of the theory of generalized Cosserat continuum is presented, the elastoplastic model of Bogdanova-Bontcheva and Lippmann is described, together with details of the computational implementations. Finally, analyses of well geometries with the implemented Cosserat based elastoplastic models are shown,identifying the failure mechanisms.
344

[en] EXPERIMENTAL STUDY OF MECHANISMS OF SAND PRODUCTION USING X-RAY COMPUTERIZED TOMOGRAPHY / [pt] ESTUDO EXPERIMENTAL DOS MECANISMOS DE PRODUÇÃO DE AREIA EMPREGANDO TOMOGRAFIA COMPUTADORIZADA DE RAIOS-X

JANAINA BARRETO SANTOS 26 August 2004 (has links)
[pt] Durante a fase produtiva de um poço de petróleo ou gás, muitas vezes há a produção simultânea de partículas sólidas arrancadas da matriz da rocha reservatório. Este fenômeno recebe o nome de produção de areia. Neste caso as tensões e as condições de fluxo nas vizinhanças do poço são fatores fundamentais para a deflagração do processo. As tensões que se concentram na parede do poço com a perfuração do mesmo, pode ser de tal magnitude que pode causar a perda da coesão entre os grãos e criando , assim , uma região de material granular susceptível ao arraste pelas forças de percolação derivadas do fluxo. Este trabalho visou a realização de ensaios em amostras de arenito Rio Bonito e arenito sintético utilizando a técnica da Tomografia Computadorizada de Raios-X para acompanhamento em tempo real dos ensaios. Os ensaios tiveram por objetivo identificar a pressão de início e o modo de propagação da ruptura da parede da cavidade interna da amostra ensaiada. Estes são estágios iniciais dos processos de produção de areia em rochas. As análises das imagens tomográficas adquiridas durante os ensaios permitiram a visualização de breakouts e arrombamentos dos poços. Estudos mais detalhados possibilitaram estimar a quantidade de areia produzida e reconstruir tridimensionalmente o processo de propagação da ruptura. / [en] During productive phase of the well, manytimes there is simultaneous production of the solid particles detached from matrix of the reservoir rock. This phenomenon receive the name of the sand production. In this case stress and flow conditions around of the well are fundamental factors for deflagration of the process. Stress concentration in the wall of the well lead to the loss of cohesion between grains arising, consequently, a granular material region susceptible for dragging by seepage forces derived from fluid flow. The objective of this work was to perform sand production tests in Rio Bonito and synthetic sandstone samples using real-time X-Ray Computerized Tomography. The tests investigated the initial and the evolution of failure at the cavity wall of samples. These are initial stages of the sand production process. The analysis of the CT-scans obtained during tests allowed the visualization of breakouts and collapses of the wells. From studies more details were possible estimate the sand production and produce 3-D images of the propagation of the failure.
345

Liquefaction Characteristics of Sand Reinforced with Small Percentages of Polypropylene FIber

Tripathi, Sudhir Kumar 01 May 2018 (has links)
Liquefaction of soil is one of the major contributing factors for damages of infrastructures and utility services during earthquake. Liquefaction occurs when short strong shaking creates undrained loading condition in saturated soil deposit thereby increases pore water pressure, which eventually equals the effective confining pressure resulting in significant reduction in shear strength and bearing capacity of soil deposit. Several studies have been conducted to investigate the effect of polypropylene fiber on sand deposit as a measure to prevent liquefaction but most of them are based on static tests. Therefore, the present study, tries to understand liquefaction characteristics of sand reinforced with polypropylene fiber based on cyclic triaxial test. The main objectives of this study are (i) to explore the effect of polypropylene fiber on pore pressure generation and deformation characteristics of sand, and (ii) to observe the effect of confining pressure on liquefaction characteristics of sand-fiber mixture. A series of stress controlled cyclic triaxial tests were performed at 5 and 10 psi effective confining pressures. At 5 psi effective confining pressure, specimens of clean sand, and sand containing 0.05, 0.075, 0.1, and 0.3% polypropylene fiber by dry weight were tested at 0.2, 0.25, 0.3, and 0.4 Cyclic Stress Ratio (CSR). However, at 10 psi effective confining pressure, specimens were also tested for 0.5%, and 0.75% fiber in addition to those at 5 psi confining pressure at 0.2, 0.3, and 0.4 CSR. Based on the test results, it was observed that, cyclic shear stress increases with the increase in initial effective confining pressure. Also, for a given CSR, liquefaction resistance decreased with the increase in effective confining pressure. Furthermore, significant improvement in liquefaction resistance was observed when the fiber content exceeded beyond 0.075% at 5 psi confining stress. However, at 10 psi confining pressure, addition of fiber did not help in improvement of liquefaction resistance of sand except when cyclic shear stress was applied at 0.2 CSR. At 0.2 CSR, although the specimens did liquefy based on pore pressure generation criteria at all fiber contents, specimens containing 0.5% and 0.75% fiber did not ever reach 2.5% and 5% DA (Double Amplitude) deformation throughout 1000 loading cycles.
346

A System for Detecting the Position of a Molten Aluminum Metal-Front within a Precision Sand Mold

Foley, Brian M. 10 January 2009 (has links)
Manufacturers of cast metal parts are interested in the development of a feedback control system for use with the Precision Sand-Casting (PSC) process. As industry demands the ability to cast more complex geometries, there are a variety of challenges that engineers have to address. Certain characteristics of the mold, such as thick-to-thin transitions, extensive horizontal or flat surfaces, and sharp corners increase the likelihood of generating defective casts due to the turbulent metal-flow during fills. Consequently, it is critical that turbulent flow behavior within the mold be minimized as much as possible. One way to enhance the quality of the fill process is to adjust the flow rate of the molten metal as it fills these critical regions of the mold. Existing systems attempt to predict the position of the metal level based on elapsed time from the beginning of the fill stage. Unfortunately, variability in several aspects of the fill process makes it very difficult to consistently predict the position of the metal front. A better approach would be to embed a sensor that can detect the melt through a lift-off distance and determine the position of the metal-front. The information from this sensor can then be used to adjust the flow rate of the aluminum as the mold is filled. This thesis presents the design of a novel non-invasive sensor monitoring system. When deployed on the factory floor, the sensing system will provide all necessary information to allow process engineers to adjust the metal flow-rate within the mold and thereby reduce the amount of scrap being produced. Moreover, the system will exhibit additional value in the research and development of future mold designs.
347

George Sand and Rewriting: The Poetics of Intertextuality in George Sand's "Jacques Cycle"

Leung, Cathy Kit-Ting January 2013 (has links)
Until now, for George Sand scholars, two main images of the Sand corpus have been dominant, “un grand fleuve d’Amérique” and “une grande oeuvre multiforme.” While both images evoke the strength and diversity of styles, approaches and genres in Sand’s literary production, they also suggest a certain vagueness in regards to the contours of this oeuvre. Moreover, when speaking about the author’s novelistic writing, scholars and the larger reading public alike often refer to her work as the “eighty or so” novels and short stories she wrote, giving the impression that her work knew no boundaries. In place of this relative sense of unruliness, I propose the vision of an oeuvre unified by a strong theory of the novel and suggest how this corpus is structured by both intertextuality and polyphony. For this purpose, I borrow from Riffaterrian theories of textuality while proposing my own theory of intertextuality in regards to its function in the Sand corpus. I explain how George Sand hands us an actual key to deciphering her entire literary production and how one can understand the theoretical implications of this literary gesture. This key is what I call the author’s “Jacques cycle,” the series of rewritings of her 1834 novel Jacques that she highlights in her 1866 novel Le Dernier Amour. There, the author speaks about Jacques and its rewritings as key novels that have followed the evolution of her thinking as a writer in addition to her reflections on societal concerns. Viewed from this perspective, Sand places intertextuality, rewriting, and metaliterary reflection at the very heart of her conception of literature on the same plane as her societal preoccupations. My dissertation consists of an Introduction, four chapters and a Conclusion. Chapter One presents George Sand's engaged stance in her "Essai sur le drame fantastique" theorizing on intertextuality. Chapter Two demonstrates how her rewriting of La Nouvelle Héloïse in Jacques enters in dialogue with the horizons d'attente associated with women's writing, while constructing what has been called a textual masculinity. Chapter Three analyzes Sand's defense of the autonomy of literature in Jacques and her article, "À propos de Lélia et de Valentine." Chapter Four theorizes on the concept of a Jacques cycle and investigates Sand's Valvèdre and Le Dernier Amour as novels rewriting Jacques in light of the movement of "l'art pour l'art." Theory is thus central in shaping the Sand corpus.
348

The effect of physical properties of sand on the performance of sand mesh turf tracks in Hong Kong.

January 2004 (has links)
Law Shun-ying, Shirley. / Thesis submitted in: June 2003. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 134-138). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iii / List of Tables --- p.iv / List of Figures --- p.vi / Chapter CHAPTER 1 --- INTRODUCTION / Chapter 1.1 --- The Hong Kong Jockey Club --- p.1 / Chapter 1.2 --- History of Sand Mesh System in Hong Kong --- p.2 / Chapter 1.3 --- Problems Encountered in Track Maintenance --- p.3 / Chapter CHAPTER 2 --- CONCEPTUAL FRAMEWORK OF STUDY / Chapter 2.1 --- Sand and Sand Mesh Systems --- p.9 / Chapter 2.2 --- The Basic Components of a Turf Track System --- p.11 / Chapter 2.3 --- Track Characteristics --- p.14 / Chapter 2.3.1 --- Hardness --- p.14 / Chapter 2.3.2 --- Stability --- p.17 / Chapter 2.4 --- Problems Encountered in Sand Mesh Systems --- p.20 / Chapter 2.4.1 --- Maturity of sand mesh system --- p.20 / Chapter 2.4.2 --- Surface instability in the early years after construction --- p.22 / Chapter 2.4.3 --- Shading of sections of the Happy Valley track --- p.24 / Chapter 2.5 --- Objectives of Study --- p.26 / Chapter 2.6 --- Hypothesis of Study --- p.26 / Chapter 2.7 --- Significance of Study --- p.27 / Chapter CHAPTER 3 --- LITERATURE REVIEW / Chapter 3.1 --- Components of a Turf Track --- p.28 / Chapter 3.2 --- Age Development in Sand Based Turf --- p.30 / Chapter 3.3 --- Surface Stability of Sand Rootzone --- p.32 / Chapter 3.4 --- Physical Properties and Botanical Cmposition --- p.34 / Chapter 3.5 --- Significance of Macropores --- p.42 / Chapter 3.6 --- Water Retention --- p.43 / Chapter 3.7 --- Ideal Sand Medium --- p.45 / Chapter CHAPTER 4 --- METHODOLOGY / Chapter 4.1 --- Study Site --- p.46 / Chapter 4.2 --- Sampling Period / Chapter 4.2.1 --- "September, after the commencement of first race" --- p.51 / Chapter 4.2.2 --- Mid-December to January --- p.51 / Chapter 4.2.3 --- April --- p.52 / Chapter 4.2.4 --- "June, before the on-set of summer renovation" --- p.52 / Chapter 4.3 --- Sampling Method --- p.53 / Chapter 4.4 --- Physical Qualities of Sand / Chapter 4.4.1 --- Moisture release characteristics --- p.54 / Chapter 4.4.2 --- Saturated hydraulic conductivity --- p.58 / Chapter 4.4.3 --- Unsaturated hydraulic conductivity --- p.59 / Chapter 4.4.4 --- Oxygen diffusion rates --- p.62 / Chapter 4.5 --- Grass Bio grass / Chapter 4.5.1 --- "Topgrowth, stolons and roots" --- p.63 / Chapter 4.6 --- Performance Indicator / Chapter 4.6.1 --- Track hardness --- p.65 / Chapter 4.6.2 --- Shear strength --- p.67 / Chapter 4.6.3 --- Divot assessment --- p.68 / Chapter CHAPTER 5 --- THE STUDY OF PERFORMANCE INDICATORS AND PROFILE PHYSICAL PROPERTIES / Chapter 5.1 --- Performance Indicators / Chapter 5.1.1 --- Race times --- p.71 / Chapter 5.1.2 --- Shear strength --- p.73 / Chapter 5.1.3 --- Vertical penetration resistance and hardness --- p.77 / Chapter 5.2 --- Analysis of Physical Properties of Sand / Chapter 5.2.1 --- Moisture release characteristics / Chapter 5.2.1.1 --- Age and moisture release curves (MRC) in Shatin Turf Track --- p.80 / Chapter 5.2.1.2 --- MRC and profile design in Happy Valley Old and New Sections --- p.83 / Chapter 5.2.2 --- Saturated and unsaturated hydraulic conductivity / Chapter 5.2.2.1 --- Hydraulic conductivity in Shatin --- p.85 / Chapter 5.2.2.2 --- Hydraulic conductivity in Happy Valley --- p.87 / Chapter 5.2.3 --- Oxygen diffusion rates / Chapter 5.2.3.1 --- ODR and profile age in Shatin --- p.90 / Chapter 5.2.3.2 --- ODR and profile design in Happy Valley --- p.91 / Chapter 5.2.4 --- Grass biomass / Chapter 5.2.4.1 --- Biomass and variation in profile age in Shatin --- p.92 / Chapter 5.2.4.2 --- Biomass and variation in profile design in Happy Valley --- p.93 / Chapter 5.2.4.3 --- Biomass and the effect of shade in Happy Valley --- p.93 / Chapter 5.2.5 --- Track hardness / Chapter 5.2.5.1 --- Track hardness and variation in profile age in Shatin --- p.94 / Chapter 5.2.5.2 --- Track hardness and variation in profile design in Happy Valley --- p.96 / Chapter 5.2.6 --- Shear strength / Chapter 5.2.6.1 --- Shear strength and variation of profile age in Shatin --- p.98 / Chapter 5.2.6.2 --- Track hardness and variation in profile design in Happy Valley --- p.99 / Chapter 5.3 --- Correlation between Soil Physical Properties and Performance index / Chapter 5.3.1 --- Correlation between soil physical properties and shear strength value --- p.100 / Chapter 5.3.2 --- Correlation between soil physical properties and surface hardness --- p.101 / Chapter CHAPTER 6 --- CONCLUSIONS / Chapter 6.1 --- Summary of Findings --- p.118 / Chapter 6.2 --- Implications of Study / Chapter 6.2.1 --- Target levels of performance indicators --- p.120 / Chapter 6.2.1.1 --- Surface strength target level --- p.121 / Chapter 6.2.1.2 --- Surface hardness target level --- p.122 / Chapter 6.2.2 --- Turf management and cultural practice implications / Chapter 6.2.2.1 --- Effect of aging and variations of profile age in Shatin --- p.123 / Chapter 6.2.2.2 --- Effect of different profile design in Happy Valley --- p.125 / Chapter 6.2.2.3 --- Effect of shading in Happy Valley --- p.126 / Chapter 6.2.3 --- Construction material and design --- p.126 / Chapter 6.2.4 --- Managing user intensity --- p.127 / Chapter 6.3 --- Limitations of Study --- p.128 / Chapter 6.4 --- Further Studies / Chapter 6.4.1 --- Shear strength tester --- p.129 / Chapter 6.4.2 --- Maximum life of sand mesh profile --- p.129 / Chapter 6.4.3 --- Problems with newly constructed profile --- p.130
349

George Sand, une féministe avant l´heure ?

El Alami, Souad January 2018 (has links)
Ce mémoire met en lumière les détails de l'histoire romanesque d'Indiana, jeune Créole victime de la domination masculine et de la pression imposée par la société de l'époque, mais aussi et surtout le message féministe véhiculé par George Sand à travers son oeuvre Indiana. Après avoir montré les liens étroits qui existent entre la vie de l'auteur et le personnage fictif d'Indiana qu´elle mit en scène dans son roman éponyme, nous avons présenté les personnages principaux et nous avons analysé l'oeuvre à travers le prisme d'un féminisme réaliste, romantique et toujours actuel. Le mémoire a aussi interrogé la manière dont le roman a reflété les conditions sociales et légales des femmes à l´époque de sa publication et l'accueil réservé aux élites intellectuelles comme de la part des lecteurs d'hier et d'aujourd'hui. Il est apparu qu´il y a eu des critiques élogieuses malgré une certaine réserve, quant au tableau peu reluisant que l'auteur brosse des femmes mariées soumises au diktat de lois machistes. L'analyse conclut sur l'audace d'une George Sand, fer de lance du féminisme dont elle a été l´une des pionnières. / This essay brings to light the details of the story of Indiana, a young Creole victim of male domination and the pressure imposed by the society of the time, but also and above all the feminist message conveyed by George Sand through his Indiana. After showing the close links that exist between the life of the author and the fictitious character of Indiana that she puts in scene in her eponymous novel, it is about presenting the main characters and analyzing the work to through the prism of a realist, romantic, social and ever-present feminism. The thesis is also interested in the reception of the book when it was released, by the intellectual elites of the time as well as by the readers of yesterday and today. He underlines rave reviews despite a certain reservation as to the gloomy picture that the author portrays of married women subjected to the diktat of macho laws. The analysis concluded on the boldness of a George Sand spearhead of feminism, one of the pioneers of which she was.
350

Sediment heterogeneity and sand production in gas hydrate extraction, Daini-Atsumi Knoll, Nankai Trough, Japan

Murphy, Amanda Jane January 2018 (has links)
The possibility of commercial natural gas production from gas hydrates has been tested by researchers and industry for more than ten years. Depressurisation of gas hydrates in porous and permeable sandstones has successfully produced water and natural gas. However long term sustainable production is still elusive. Catastrophic sand production into the wellbore has terminated at least three of the significant depressurisation trials including the 2013 trial at the Daini-Atsumi knoll, Nankai Trough, offshore Japan. Sand production is generally thought to be the result of mechanical and hydrodynamic instability, however it appears the failure mechanism is not the same for all reservoirs and the location of reservoir porosity and pressure on the normal compression line for sands could be a controlling factor. Sand production in reservoirs at shallow depths and low confining stresses (less than 10 MPa) are likely to be influenced by fluid flow effects like those described by the Shields (1936) diagram. The relative density of the formation may also affect the nature of the sand production in these reservoirs. The Daini-Atsumi knoll is a structural high on the outer ridge of the Kumano forearc basin, offshore Japan. Hydrate saturations of 50 to 80 % occur within three geological units of the Middle Pleistocene Ogasa group. This group is made up of deep water sediments including sediment gravity flow deposits distinguished by alternating silt and sand layers. The presence of these alternating layers could have influenced the sand production seen during the trial. This reservoir heterogeneity at the 2013 Daini-Atsumi knoll gas hydrate production trial site was characterised using the descriptions of geological units, analogues and statistical techniques. Scenarios of this heterogeneity were tested in a high pressure plane-strain sand production apparatus. The results of these tests suggest the boundary shear stress of the fluid on the grains is a significant control on sand production for the Daini-Atsumi Knoll reservoir and the layering and grainsize structure of the sediments encourages sand production. Relative density of the sediments appears to impact the nature of the sand production where denser sediments show more localised movement. These results indicate that even minor weaknesses in sand control devices will result in uncontrollable sand production rates from the Daini-Atsumi Knoll gas hydrate reservoir. Managing the fluid flow rate in the reservoir and selectively completing coarser grained zones at the base of sand layers could help limit sand production in future trials.

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