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Hydraulic fracturing
Mazáček, Michal ; Mls, Jiří (advisor) ; Fischer, Tomáš (referee)
This bachelor thesis deals with the process of hydraulic fracturing. Hydraulic fracturing (also called fracking or fracjob) is a method used for the stimulation of the oil or gas reservoirs. The point of the method is to inject the liquid under high pressure into the formation. The injection cause widening of existing fractures or making new ones. The goal of this thesis was to describe basic knowledge that are necessary to successful treatment. There were basics of rock mechanics described such as linear elasticity, plasticity etc. The main chapter describes the parameters of the fracture such as fracture wide, fracture height, fluid flow and fluid loss. Furthermore, the kinds of liquids were discussed in one chapter. In the end, the fracturation which had been done in Texas(USA) were shown and the spreading of the fractures were discussed.
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Tidal phenomena in groundwater hydraulics
Ondovčin, Tomáš ; Mls, Jiří (advisor) ; Šembera, Jan (referee) ; Novotný, Oldřich (referee)
Manifestations of the tidal force have been known to humanity since an- tiquity. The oldest extant remarks on the origin of the tidal force are in the Natural History of Pliny the Elder. He also left us remarks on periodic changes of water-level in wells. This phenomenon does not necessarily have to be connected to the proximity of seas. As such, it is a subject of research since the end of 19th century. Exploring the mechanisms with which the tidal force affects the groundwater level requires combining the findings of geology and hydrogeology but also the knowledge of hydraulics and geomechanics of porous media and certain understanding of astronomy. This thesis contribu- tes to the knowledge of the mechanism of tidal oscillations in groundwater measured in a borehole near Teplice nad Metují in Police Basin. It utilizes models based on the knowledge of geological and hydrogeological structure of the surroundings of the borehole. It investigates the relation between the physical properties of porous media and the amplitude and phase of the tidal oscillations and presents solutions of the models.
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Hydromechanic characteristics of clay suspensions
Sedláčková, Markéta ; Mls, Jiří (advisor) ; Císlerová, Milena (referee) ; Šembera, Jan (referee)
A mathematical model of two-phase systems, such as clay suspensions, consists of a set of partial differential equations which reflect both the general laws of mechanics and the relations connecting the involved characteristics of the particular system under consideration. The latter equations are known as constitutive relations. The aim of this study was to find the constitutive relations for kaolin suspensions that are necessary when solving forward problems of fine sludge thickening processes. The task was to design and carry out experimental research of the given suspension and to find a convenient method of utilizing the results for the sake of getting the sought relationships. It follows from the applied mathematical theory of two-phase systems that the sought relationships are hydraulic conductivity of the suspension as a function of the solid-phase concentration and the dependence of the solid-phase concentration on the solid-phase stress. The first part of this study describes the experimental research. Since both the characteristics are difficult to measure, it was necessary to analyze the suspension's characteristics and their measurability. Subsequently, the process of the suspension preparation and the method of laboratory measurements were determined. The following sections present...
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Mathematical model of groundwater flow in the Police basin
Grecká, Marie ; Mls, Jiří (advisor) ; Ondovčin, Tomáš (referee)
The topic of this thesis is a groundwater modelling of the cenomanian sediments in the north area of the Police basin. The text is divided into a part of a characterization of the cretaceous sediments from geological and hydro-geological view based on literature. Another part is about a theory of the mathematical modelling in hydrogeology. The main part is related to the groundwater model of the Police basin. This part contains concept and description of the groundwater modelling in software Feflow, which is based on the finite element method. The results, (of the two variants with slightly different boundary conditions), are compared to the model of the same area from the authors Jakeš et al. (1996), who used another software (Modflow) with a different method of the calculation (the finite difference method).
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Mathematical model of groundwater flow affected by circulation wells
Nedvěd, Jakub ; Mls, Jiří (advisor) ; Ondovčin, Tomáš (referee)
In this thesis, I focused on numerical modelling of groundwater flow in the vicinity of groundwater circulation well (GCW). The thesis can be devided to two parts. In the first one, I created a simple numerical model of GCW. I used a cylindrical flow domain because of the radial symmetry of the problem. The task was to find out which parameters have the biggest influence on groundwater flow. It was found that the hydrogeological settings and hydraulic properties have more considerable effect on GW flow than the well construction parameters. Distance between the well screens is the only important construction parameter, other parameters can be neglected. However, we cannot neglect the influence of hydraulic properties of the porous medium. Considering the radius of influence of GCW, the presence of aquitards and anisotropy of layers affect the groundwater flow around the well seriously. These two parameters cause the extension of the radius of influence, which leads to a longer path of the particle of water. The travel time of particles increases too this slows down the remediation. A big influence has also an intensity of natural groundwater flow in the area because it decreases the radius of influence of the well. In the second part I created a numerical model of pilot site Velká Hleďsebe to investigate...
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Mathematical model of groundwater flow during operation of a circulation well
Žáková, Tereza ; Mls, Jiří (advisor) ; Šindelář, Jakub (referee)
In this master's thesis, a numerical model of groundwater flow in a contaminated area of Hradec Králové was created. After that, a circulation well was introduced. Two circulation well variants, which differ in the amount of pumped water, were examined. All simulations were performed with the aid of a finite element solver Feflow 5.2. The values of hydraulic head resulting from the mathematical model are in a good agreement with those obtained from the field measurement. The groundwater flow present in the area of interest exhibits south to southwest direction. After introducing the circulation well, I focused on the influence of the amount of pumped water on the groundwater flow. The outcome of this observation was that during the higher volume pumping, the circulation cell is larger and therefore has a higher influence on the groundwater flow. I evaluated that it is more efficient to pump a higher amount of water in the investigated area.
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Modelling dependence of chlorinated hydrocarbons biodegradation on changes of temperature and redox conditions in ATES sytems
Havlíková, Barbora ; Mls, Jiří (advisor) ; Datel, Josef (referee)
The Aquifer Thermal energy Storage (ATES) system is one of the most important techniques, that use the aquifer as an energy storage for heating and cooling the buildings. The operation of the ATES system is based on pumping the cold ground water into the buildings during the summer and then injecting the warmer water back into the aquifer. During the winter, the direction is reversed. Warm water is pumped to the buildings, where it serves for the heating system and then it is injected back into the aquifer. The ATES system has a main effect on the chemical composition of ground water, because of changes in the temperature of ground water, mixing of water from different redox zone and increasing of ground water flow in the neighbourhood of the wells of the ATES system. The modification in chemical composition and temperature could influence the behaviour of contaminants. If we want to install the ATES system into a contaminated aquifer, we have to know, if the ATES system would influence the behaviour of the contaminant plume positively or negatively. This study was made to increase the understanding of the dependence between changes of temperature and oxidation-reduction conditions in the ATES system and biodegradation of chlorinated hydrocarbons. In the first part, several scenarios were modelled...
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