• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 7
  • 6
  • 4
  • 3
  • 1
  • Tagged with
  • 34
  • 11
  • 10
  • 9
  • 8
  • 8
  • 7
  • 6
  • 6
  • 6
  • 6
  • 6
  • 6
  • 5
  • 5
  • 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.
21

Charakterizace hydrogeologického masivu na základě archivních vrtných prací a konceptuální model / Characterization of hard rock environment: archive borehole data and conceptual model

Vacková, Alena January 2014 (has links)
This study is focused on characterization of the hardrock environment in surroundings of Sazava river. It is based on the archival data of groundwater table in boreholes, results of pumping tests from Geofond database and topographic data (DMR , watercourse, etc.). ArcMap 10.1 and Excel were used for data processing. The relations between the groundwater table depth, water table gradient, specific yield, transmissivity and variety of topographic parameters (distance from a watercourse, elevation, relative elevation above the nearest watercourse, the terrain gradient, etc.) were studied. Close linear relationship exists between the gradient of the terrain and groundwater table (rxy 0.96) in the study area. Groundwater table gradient is on average 88 % of terrain gradient. Mean groundwater table gradient is 10 % (6). The average transmissivity in the area is 1.27 x 10-4 m2 /s, specific yield is usually between 0.01 and 0.1 l/s m. This corresponds to the low and very low transmissivity class. Variability of transmisivity values is high. The difference between transmisivity in discharge and recharge zone, assumed by previous authors, was not confirmed in the study area. Specific base flow calculated from mean transmissivity, terrain/ water table gradient and river network density based on Krásný and...
22

PERFORMANCE OF GEOSYNTHETIC CLAY LINERS IN COVER, SUBSURFACE BARRIER, AND BASAL LINER APPLICATIONS

Hosney, Mohamed 28 February 2014 (has links)
The use of geosynthetic clay liners (GCLs) as (i) covers for arsenic-rich gold mine tailings and landfills, (ii) subsurface barrier for migration of hydrocarbons in the Arctic, and (iii) basal liner for sewage treatment lagoons were examined. After 4 years in field and laboratory experiments, it was found that best cover configuration above gold mine tailings might include a layer of GCL product with polymer-enhanced bentonite and a geofilm-coated carrier geotextile serving above the tailings under ≥ 0.7 m overburden. However, acceptable performance could be achieved with using a standard GCL with untreated bentonite provided that there is a minimum of 0.7 m of cover soil above the GCL. When GCL samples were exhumed from experimental landfill test cover with complete replacement of sodium in the bentonite with divalent cations in the adjacent soil, it was observed that the (i) hydraulic head across the GCLs, (ii) size of the needle-punched bundles, and (iii) structure of the bentonite can all significantly affect the value of the inferred in-situ hydraulic conductivity measured at the laboratory. The higher the hydraulic head and the larger the size of the needle-punched bundles, the higher the likelihood of internal erosion/structural change of bentonite at bundles that will cause a preferential flow for liquids to occur. A key practical implication was that GCLs can perform effectively as a single hydraulic barrier in covers provided that the water head above the GCL kept low. The hydraulic performance of a GCL in the Arctic was most affected by the location within the soil profile relative to the typical groundwater level with the highest increase in the hydraulic conductivity (by 1-4 orders of magnitude) for GCL below the water table. However, because the head required for jet fuel to pass through the GCL was higher than that present under field conditions, there was no evidence of jet fuel leakage through the barrier system. The leakage through GCLs below concrete lined sewage treatment lagoons was within acceptable limits, in large part, due to the low interface transmissivity between GCLs and the overlying poured concrete. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2014-02-28 08:53:29.171
23

The impact of the radiation balance on snowmelt in a sparse deciduous birch forest

Turton, Rachael Heather January 2017 (has links)
The representation of high-latitude surface processes and quantifying surface-climate feedbacks are some of the most serious shortcomings of present day Arctic land surface modelling. The energy balance of seasonally snow-covered sparse deciduous forests at high latitudes is poorly understood and inaccurately represented within hydrological and climate models. Snow cover plays an important role in wintertime fluxes of energy, water and carbon, controlling the length of the active growing season and hence the overall carbon balance of Arctic ecosystems. Snow cover is non-uniform and spatially variable, as wind redistributes snow from areas of exposed open tundra to sheltered areas within the forest, where a deeper snowpack develops. Low solar zenith angles, coupled with sparse deciduous leafless trees, cast shadows across the snow surface. The spatial distribution of canopy gaps determines the timing of direct radiation which penetrates down through the canopy to the snow surface. The forest canopy also excludes incoming longwave radiation and yet also emits longwave radiation to the snow surface. Consequently the forest canopy plays a key role in the radiation balance of sparse forests. To improve our knowledge of these complex processes, meteorological and field observations were taken in an area of highly heterogeneous birch Betula pubescens ssp. czerepanovii forest in Abisko, Sweden during the spring of 2008 and 2009. Detailed measurements of short and longwave radiation above and below the canopy, hemispherical photographs, tree temperatures and snow surveys were conducted to quantify the radiation balance of the sparse deciduous forest. An array of below canopy pyranometers found the mean canopy transmissivity to be 74 % in 2008 and 76 % in 2009. Hemispherical photographs taken at the pyranometer locations analysed with Gap Light Analyzer (GLA) showed reasonable agreement with a mean canopy transmissivity of 75 % in 2008 and 74 % in 2009. The canopy transmissivity was found to be independent of the diffuse fraction of radiation as the canopy is very sparse. A series of survey grids and transects were established to scale up from the below canopy pyranometers to the landscape scale. Hemispherical photographs analysed with GLA showed the sparse forest canopy had a mean transmissivity of 78 % and a mean LAI of 0.25, whereas the open tundra had a mean transmissivity of 97 % and a mean LAI of < 0.01. Snow surveys showed the sparse forest snow depth to vary between 0.34 and 0.55 m, whereas the snow depth in the open tundra varied between 0.12 and 0.18 m. Observations of canopy temperatures showed a strong influence of incident shortwave radiation warming the tree branches to temperatures up to 15 °C warmer than ambient air temperature on the south facing sides of the trees, and up to 6 °C on the north facing sides of the trees. To reproduce the observed radiation balance, two canopy models (Homogenous and Clumped) were developed. The Homogeneous canopy model assumes a single tree tile with a uniform sparse canopy. The Clumped canopy model assumes a tree and a grass tile, where the tree tile is permanently in shade from the canopy and the grass tile receives all the incoming radiation. These canopy models identified the need for a parameter that accounts for the spatial and temporal variation of the shaded gaps within the sparse forest. JULES (Joint UK Land Environment Simulator) is the community land surface model used in the UK Hadley Centre GCM suite. Modifications of the land-surface interactions were included in JULES to represent the shaded gaps within the sparse deciduous forest. New parameterisations were developed for the time-varying sunlit fractions of the gap (flit), the sky-view fraction (fv), and the longwave radiation emitted from the canopy (LWtree). These model developments were informed by field observations of the forest canopy and evaluated against the below canopy short and longwave radiation observed data sets. The JULES Shaded gap model output showed a strong positive relationship with the observations of below canopy shortwave and longwave radiation. The JULES Shaded gap model improves the ratio of observed to modelled short and longwave radiation on sunny days compared to the JULES model. The JULES Shaded gap model reduces the time to snow melt by 2 to 4 days compared to the JULES model, making the model output more aligned with in-situ observational data. This shortening of the modelled snow-season directly impacts on the simulated carbon and water balance regionally and has wider relevance at the pan-Arctic scale. When JULES Shaded Gap was evaluated on the global scale, it improved the modelled snowmass across large areas of sparse forest in northern Canada, Scandinavia and Northern Russia with respect to GlobSnow. The performance of the land surface-snow-vegetation interactions of JULES was improved by using the Shaded gap to model the radiation balance of sparse forests in climate-sensitive Arctic regions. Furthermore these observational data can be used to develop and evaluate high latitude land-surface processes and biogeochemical feedbacks in other earth system models.
24

Otimização de um sistema de aquecimento de água com mangueira de polietileno: estudo de caso / Optimization of a water heating system with polyethylene hose: case study

Queiroz, José Aparecido Silva de [UNESP] 29 April 2016 (has links)
Submitted by JOSÉ APARECIDO SILVA DE QUEIROZ null (jqueiroz@unilins.edu.br) on 2016-06-28T17:33:24Z No. of bitstreams: 1 TESE FINAL JOSÉ QUEIROZ.pdf: 1990890 bytes, checksum: 8dbd46996efdf66f13c164f994bd6087 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-06-29T20:20:08Z (GMT) No. of bitstreams: 1 queiroz_jas_dr_bot.pdf: 1990890 bytes, checksum: 8dbd46996efdf66f13c164f994bd6087 (MD5) / Made available in DSpace on 2016-06-29T20:20:08Z (GMT). No. of bitstreams: 1 queiroz_jas_dr_bot.pdf: 1990890 bytes, checksum: 8dbd46996efdf66f13c164f994bd6087 (MD5) Previous issue date: 2016-04-29 / O principal objetivo deste estudo é avaliar, com bases em resultados experimentais, um sistema de aquecimento solar constituído de mangueira de polietileno que permite a transferência do calor gerado pela radiação solar direta e/ou difusa (Energia Solar Térmica) para a água. O sistema foi dimensionado para atender a demanda de um Centro de Ressocialização com capacidade para 220 internos. Justifica-se a escolha do tema pelo fato de que consiste em um assunto atual de grande relevância, principalmente porque vive-se uma crise energética em nível mundial. O estudo comprova através de um experimento a viabilidade do aquecedor solar de baixo custo, considerando-se sua aplicabilidade em locais que demanda grande volume de água aquecida para banho. Os resultados demonstraram que o sistema alternativo proposto atendeu de forma eficiente e econômica a demanda solicitada, o que pode ser adotada pelo poder público em qualquer um de seus segmentos que necessite de água aquecida, com objetivo de reduzir custos e contribuir com o sistema energético brasileiro. O sistema foi analisado para atuar em fluxo continuo e fluxo intermitente, ambos objetivando aquecer a água a temperaturas superiores a 37 °C no inverno. Os resultados alcançados atenderam as expectativas coletando grandes volumes, com temperaturas médias acima de 42 °C. / The aim of this study is to evaluate, with bases on experimental results, a solar heating system consists of polyethylene hose that allows the transfer of heat generated by direct solar radiation and / or diffuse (Solar Thermal Energy) to the water. The system has been designed to meet the demand of a Rehabilitation Center with a capacity for 220 inmates. Justified the choice of the theme for the fact that consists of a current subject of great importance, especially because it lives in an energy crisis worldwide. The study proves through an experiment the viability of solar heater low cost, considering their applicability in places that demand large volume of heated water for bathing. The results showed that the alternative system proposed met efficiently and economically the requested demand, which can be adopted by the government in any of its segments that need heated water, in order to reduce costs and contribute to the Brazilian energy system. The system was analyzed to operate in continuous flow, intermittent flow, both aiming at heating the water to temperatures above 37 °C in winter. The results achieved met the expectations collecting large volumes, with average temperatures above 42 °C.
25

Groundwater management model for the Spitskop area in South Africa

Bulasigobo, Ridovhona Joubert January 2014 (has links)
Masters of Science / The thesis investigates the potential of the Rietfontein and Spitskop aquifer to meet a demand of 1000 m3/d (12 Lis) as an alternative water resource for the Rietfontein and Spitskop Community. Increasing demand for clean and hygienic drinking water puts more pressure on one of our most valuable resources and supplying all communities with surface water is an extremely difficult and costly task in rural areas like Rietfontein and Spitskop in South Africa. Therefore it is necessary that interim water supplies be found from local aquifers and be utilized to address water supply challenges. Groundwater may serve as a short-term and an interim water supply which may be useful during future dry periods. Abstraction of groundwater is sensitive to recharge. Due to semi-arid conditions in Rietfontein and Spitskop area, there is high rainfall variation and disparity each year. During the research, hydrocensus was carried out. Water samples for chemistry analysis were taken. Literature review and pumping test data was utilized from the previous studies done by different consultants (Botha, 2000, Vivier and Pretorius, 2003). A numerical groundwater flow model for the local aquifers in the area and surroundings was constructed focusing on recharge and abstraction scenarios for the water supply from the local aquifers. For Rietfontein and Spitskop area, the mean annual precipitation (MAP) is 617mm/year. To be assured and rational in determining aquifers ability to meet the required demand a recharge with ninety-five (95th ) percentile was recommended, which estimates the MAP of 308mm/year which is 50% lower than the average MAP of 617mm/year. For a period of ninety six (96) years, the data indicates a severe drought occurred four (4) times where the rainfall was even lower than 95th percentile level of assurance of recharge estimated. This gives a comprehensible indication that average mean is not ideal or steadfast stature when building a water supply numerical groundwater flow modelling. These aquifers can only be exploited and managed if a reliable method can be obtained to estimate their long-term sustainable potential, since the sustainable potential of these aquifers to supply the communities is dependent upon the recharge from rainfall. The results from a numerical groundwater flow model indicated that a combined potential from the local aquifer from eighteen (18) boreholes is sufficient to meet the required demand and a total of 2600m3 Id can potentially be abstracted from the aquifer. With ninety-five (95th ) percentile recharge rate of 308mm/year a numerical groundwater flow model shows that the rate of abstraction is 80% far less than recharge, which gives high level of assurance in terms of local aquifer water supply demand. The abstraction of the boreholes confirmed by a numerical groundwater flow model shows the least impact on the surrounding aquifer for an extended period of time. In the event of drought, the boreholes will see a decline in water level after two (2) months of pumping local aquifer. The water level will decline steadily from two (2) months to two (2) years with a change in water levels of up to 40m. The impact of the drought is minimal compared to recharge rate, which verifies less depletion of the aquifer. The local aquifer shows the potential of 3MLld can be supplied to the communities with an assurance level of 95th percentile of rainfall. Reliable quantification of groundwater recharge rate remains the main challenges the hydrologist experienced and further research is essential for improvement of groundwater management for the area concerned.
26

Uncertainties in Digital-Computer Modeling of Ground-Water Basins

Gates, Joseph S., | Kisiel, Chester C. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / Much future computer modeling of the responses of groundwater to water development stresses may be poorly done if the errors and limitations of digital models are not fully appreciated by groundwater hydrologists. Two digital models were constructed of the Tucson basin, one with 1,890 nodes of 1/4 square mile area each and one with 509 nodes of 1 square mile each. The starting point for the digital model was the 2-dimensional, linear, parabolic, time-and space-invariant differential equation of incompressible flow through porous media. An explicit finite-difference equivalent was determined, and a set of 1,890 equations were put in implicit form and solved on a computer in less than 20 seconds at a cost of 2.00 dollars. The errors associated with the model are discussed. In deciding what new data collected in the Tucson basin would give the most improvement in the digital model, a statistical decision theory approach was utilized in which expected opportunity loss and expected worth of sample were calculated for 5 variables. The data was computed using about 110 seconds of computer time, costing about 13.00 dollars. This technique has the advantage of including basin dynamics in estimating worth of additional data by means of using the digital model to compute all values of predicted and 'true' water levels included in the loss function.
27

Application of Bayesian Decision Theory in Well Field Design

Bostock, Charles A., Davis, Donald R. 12 April 1975 (has links)
From the Proceedings of the 1975 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 11-12, 1975, Tempe, Arizona / Bayesian decision theory is a method for comparing expected utilities of alternative actions given various possible states of nature. The method treats uncertainty as to the true state of nature by determining the expected utility of each action in terms of the probabilities of the various possible states. The decision rule is to choose the action having the best expected utility. This paper illustrates an application of Bayesian decision theory in a well field design problem where a decision had to be made regarding capacity-density combination for wells located in an extensive uniform grid. The uncertainty lay in anticipating the frequencies of transmissivity values among the wells.
28

The Application of Step-Drawdown Pumping Tests for Determining Well Losses in Consolidated Rock Aquifers

Uhl, V. W., Jr., Joshi, V. G., Alpheus, A., Sharma, G. 12 April 1975 (has links)
From the Proceedings of the 1975 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 11-12, 1975, Tempe, Arizona / The concept of a step -drawdown test was first introduced by Jacob, and further modifications in the technique were made by Rorabaugh. Analysis of step -drawdown test data enables the quantification of the components of drawdown due to formation or aquifer loss, and due to well losses in a pumped well. This technique has been used to test approximately 100 wells that were drilled in crystalline and basalt formations in central India. Test data have been analyzed by Rorabaugh's method and by a graphical method, and the results of a number of tests are presented and discussed. Anomalies in the test analysis often proved helpful for interpreting aquifer irregularities. In general, the well loss constant decreases with an increase in specific capacity and the aquifer loss constant decreases with increasing transmissivity. Significant reductions in specific capacity during a step test occur in wells with high well losses. An attempt is made to quantify the well losses in a consolidated rock well, and a number of practical applications of step -drawdown tests are discussed.
29

Influência do uso da cobertura plástica no microclima de parreirais na região do Submédio São Francisco: efeitos na produtividade e rentabilidade econômica. / Influence of the use of plastic cover in the vineyard microclimate submedium in the region of São Francisco: effects on productivity, and economic profitability.

LIMA, Paulo César da Silva. 06 November 2018 (has links)
Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-11-06T14:31:07Z No. of bitstreams: 1 PAULO CÉSAR DA SILVA LIMA - TESE (PPGRN) 2011.pdf: 2310870 bytes, checksum: e809895ded4befc59a0d2dfb97dc367c (MD5) / Made available in DSpace on 2018-11-06T14:31:07Z (GMT). No. of bitstreams: 1 PAULO CÉSAR DA SILVA LIMA - TESE (PPGRN) 2011.pdf: 2310870 bytes, checksum: e809895ded4befc59a0d2dfb97dc367c (MD5) Previous issue date: 2011-09-05 / O presente trabalho objetivou avaliar a influência da cobertura plástica de filme de polietileno de baixa densidade (PEBD), de 160 μm de espessura, transparente e de largura de 3 m, nas condições microclimáticas de parreirais cobertos na Região do Submédio São Francisco - RSMSF, na produtividade e rentabilidade econômica da viticultura de mesa da região. A pesquisa constou de quatro etapas experimentais conduzidas em parreirais produtivos de uva de mesa das variedades Festival e Itália Muscat em Petrolina, PE (09º 06’ 14’’ S; 40º 29’ 52” W; altitude 360 m) no período de outubro de 2009 a novembro de 2010. O período de cobertura ocorreu somente durante a fase de maturação e colheita da uva, como tradicionalmente é usada pelos produtores da região. Foram estudados três tratamentos: tratamento 1 – dossel sem cobertura plástica (SCob); tratamento 2 – cobertura plástica posicionada a 50 cm acima do dossel (CP50); e tratamento 3 - cobertura plástica posicionada a 100 cm acima do dossel (CP100). Cada parcela foi composta por sete plantas úteis e consecutivas de uma fileira de plantio. O monitoramento microclimático foi realizado através de sensores de temperatura e umidade relativa do ar, velocidade do vento e fluxos radiativos, instalados em três posições: abaixo do dossel na altura dos cachos, entre o dossel e a cobertura plástica e acima da cobertura na atmosfera. Os sensores foram conectados a sistemas automáticos de aquisição de dados CR23X e CR1000, programados para efetuar leituras a cada 2 segundos, gerar médias horárias e diárias e valores extremos diários. Os resultados indicaram que a cobertura plástica posicionada a 50 cm e 100 cm acima do dossel alterou o microclima do parreiral, aumentando a temperatura do ar e umidade relativa e reduzindo a velocidade do vento e reduzindo em até 40% a disponibilidade de radiação no seu interior. A transmissividade da cobertura plástica permitiu a passagem de 67% da radiação global (Rg); 55% da radiação ultravioleta (UV); 58% da radiação fotossinteticamente ativa (PAR), e 76% da radiação infravermelha (IR). No período de abril e maio, época do ano em que na região ocorrem maior nebulosidade e temperatura do ar mais amena, a cobertura plástica alterou o microclima do interior dos parreirais de uva Itália Muscat, com aumento de até 2 °C na temperatura do ar, aumento da umidade relativa em relação ao ambiente externo (com maior diferença sendo observado no dossel CP50), redução significativa da velocidade do vento, principalmente sobre o dossel, e da quantidade de cachos com defeitos no dossel CP50, em relação aos dosséis SCob e CP100. No período de setembro e outubro a produtividade física sob o dossel foi influenciada positivamente e contribuiu para uma maior disponibilidade de radiação quando comparado à cobertura do dossel CP50. O aumento da produtividade comercial, seja pela redução do número de cachos com defeitos observada no período de abril a maio no dossel CP50 ou pela maior disponibilidade de radiação no período de setembro a outubro no dossel CP100, foi determinante para a rentabilidade econômica positiva, mantendo a relação Benefício/Custo sempre maior do que 1, ampliando a margem de segurança da atividade. / This study aimed to evaluate the influence of the plastic cover film of low density polyethylene (LDPE), 160 mm thick, transparent and width of 3 m, the microclimatic conditions of the vineyards covered in the region Submédio São Francisco - RSMSF, productivity and economic profitability of viticulture table in the region. The research consisted of four experimental stages conducted in vineyards production of table grape varieties Festival and Italy Muscat in Petrolina, Pernambuco (09 ° 06 '14''S, 40 º 29' 52 "W, altitude 360 m) during October 2009 to November 2010. The coverage period occurred only during the ripening and harvesting of the grapes, as traditionally used by local farmers. Was studied three treatments: treatment 1 - no plastic cover canopy (SCob), treatment 2 - plastic cover positioned 50 cm above the canopy (CP50) and treatment 3 - plastic cover positioned 100 cm above the canopy (CP100). Each research plot consisted of seven consecutive useful plants and a row of planting. The microclimatic monitoring was performed by temperature sensors and relative humidity, wind speed and radiative flows, installed in three locations: beneath the canopy at the time of the clusters between the canopy and the plastic cover over the cover and the atmosphere. The sensors were connected to automatic data acquisition CR23X and CR1000, programmed to perform readings every 2 seconds to generate hourly and daily averages and extreme values daily. The results indicated that the plastic cover positioned at 50 cm and 100 cm above the canopy changed the microclimate of the vineyard, increasing the air temperature and relative humidity and reducing wind speed and reducing up to 40% availability of radiation inside. The transmissivity of the plastic cover allowed the passage of 67% of global radiation (Rg), 55% of the ultraviolet (UV), 58% of photosynthetic active radiation (PAR), and 76% of infrared radiation (IR). Between April and May, time of year that occur in the region increased cloudiness and air temperature more gently, the plastic has changed the microclimate of the interior of Italy Muscat grape vineyards, with up to 2 ° C in air temperature , increased relative humidity in relation to the external environment (with the main difference being observed in the canopy CP50, a significant reduction in wind speed, especially on the canopy, and the amount of defect clusters with CP50 in the canopy compared to canopies Scob and CP100. During September and October the physical productivity under the canopy was positively influenced and contributed to a greater availability of radiation when compared to canopy cover CP50. The increased business productivity, whether by reducing the quantity of clusters with defects observed during the April and May in the canopy CP50 or by increased availability of light in September and October period in canopy CP100, was decisive to positive economic return of the activity, making the benefit / cost ratio remained always greater than 1 widening of the margin of safety activity.
30

Oil Mobility Estimation and Recovery Optimization / Mobilité de l’huile dans le sol et optimisation de son extraction

Palmier, Cédric 09 November 2016 (has links)
L’objectif général de cette thèse était d’améliorer l’utilisation des éléments de diagnostic des sites pollués par des hydrocarbures légers. En particulier, il s’agissait : • De valider la méthode d’estimation de la mobilité de l’huile dans le sol, en milieu hétérogène, appelée bail-down test. Et de définir quelle méthode d’interprétation est la plus adaptée. • Comprendre l’impact des variations de hauteur de nappe sur l’épaisseur d’huile mesurée dans les puits de surveillance et sur la mobilité de l’huile. Dans un premier temps, des simulations de bail-down tests ont été réalisées en laboratoire, sur un pilote radial, remplie d’une matrice homogène. Puis, un grand nombre de tests réalisés sur un terrain d’étude, a été interprété. Ces travaux ont permis de confirmer la validité des bail-down tests pour estimer la mobilité de l’huile dans le milieu. L’hypothèse principale pour expliquer la validité de ces tests, alors que les hypothèses théoriques ne sont à priori pas respectées lors des essais, réside dans la faible mobilité de l’huile liée à une viscosité élevée. Dans un deuxième temps, l’impact des variations de nappes a été suivi par des mesures manuelles et automatiques sur le terrain d’étude, pendant plusieurs mois. Ce suivi a permis de décrire de manière précise cet impact, qui est différent pour un hydrocarbure en nappe libre, ou en milieu confiné. Par ailleurs, un modèle a été développé et testé pour simuler les variations d’épaisseur d’huile en fonction des hauteurs de nappe. Ce modèle permet d’estimer l’épaisseur et la position de l’huile dans la formation, ainsi que sa conductivité hydraulique. Les conclusions de cette étude apportent des éléments importants pour améliorer les phases d’investigation de site pollués par des hydrocarbures légers, et pour optimiser l’utilisation des données collectées. Enfin, confirmant l’impact significatif des variations de nappe sur les épaisseurs d’huile dans les puits et en montrant la validité des bail-down tests pour estimer la mobilité de l’huile, cette étude montre la nécessité de baser le dimensionnement des réseaux d’extraction des hydrocarbures, non pas sur l’épaisseur, mais sur la mobilité du produit. / The overall objective of this thesis was to improve the use of investigation data from contaminated site with light hydrocarbons. In particular, this work focused on: • To confirm the validity of the method to estimate the oil mobility in the formation, for heterogeneous conditions, called bail-down test. And, to define which interpretation method is the most relevant. • To understand the impact of the groundwater table variations on the oil thickness in the monitoring wells, and on its mobility. First, bail-down test simulations were performed at laboratory scale, on a radial pilot, filled with homogeneous sand. Then, a significant number of tests were performed on a studied site and interpreted. This work allowed to confirm the bail-down test validity for estimating the oil mobility in the formation. The key assumption to explain why these tests are valid whereas some of the assumptions and boundary conditions are not met during the tests, is based on the low mobility of the oil due to its viscosity. Secondly, the impact of the groundwater table variations has been manually and automatically measured on the studied site, during months. These measurements allowed to describe in detail the impact, which is different between confined and non-confined oil conditions. In addition, a model has been proposed and tested to simulate oil thickness depending on groundwater table level. This model allowed to estimate the thickness and the position of the oil in the formation, and its hydraulic conductivity. Overall, this study gives key elements to improve the investigation phase of site contaminated with light hydrocarbons, and to optimize the use of the collected data. Last, confirming the significant impact of the groundwater table fluctuation on the oil thickness and the validation of the bail-down test to estimate the oil mobility, this study shows the need to consider the oil mobility rather than the oil thickness for designing an oil recovery project.

Page generated in 0.0928 seconds