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Natural CO2 outburst and their relation to tectonic processes
Balák, František ; Fischer, Tomáš (advisor) ; Kolínský, Petr (referee)
This thesis is deals with the running geodynamic activity of NW Bohemia, where frequent earthquake swarms and natural CO2 emanations occur as a possible fade-out of the Tertiary rift activity. The first part summarizes the nature of these geological phenomena with a focus on CO2 escapes and its characteristics. These escapes are viewed from the viewpoint of geology and chemical and isotopic composition along with the effect of earth tides, barometric pressure and seismic activity. In the second part I analyse the records of two CO2 monitoring stations in terms of atmospheric pressure and ambient temperature.
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Seismic noise analysis at selected stations of the WEBNET network
Bachura, Martin ; Fischer, Tomáš (advisor) ; Růžek, Bohuslav (referee)
Seismic signal is affected by noise of non-geological origin. The main source of seismic noise is in human activities. Seismic noise of human origin occurs in the frequency range from one to the first tens of Hz. The noise intensity limits the lower level of the earthquake size that can be recorded by a seismic network. The aim of this thesis is to analyze the seismic noise on selected stations of the West Bohemian seismic network WEBNET which operates in the area since the early nineties. The earthquakes in West Bohemia/Vogtland are manifested in the form of long-lasting earthquake swarms with the magnitudes ranging up to ML = 3.8. The way how the seismic noise influences the seismic stations and their capability of recording small earthquakes can be classified by a statistical and time-frequency analysis. We applied this method to the selected stations NKC, KRC and SKC. The results show that the effect of noise does not deteriorate the seinsitivity of the three stations for recording small earthquakes. Despite of quite good results, some differences occur among the three stations, which are most probably caused by the distance of the stations to the populated areas. The smallest noise influence is observed at the stations located far from settlement (NKC and KRC) compared to the station located in a small...
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Relation of the alteration of the basement of the Cheb Basin and CO2 discharge
Arnetová, Kateřina ; Fischer, Tomáš (advisor) ; Boušková, Alena (referee)
The area or West Bohemia is typical by an increased geodynamic activity, which manifests itself in earthquake swarms and surface emanations of CO2 of mantle origin. These phenomena are concentrated in the tertiary Cheb basin, which is fragmented by a network of faults. The CO2 of deep origin passes along these faults to the surface and contributes to the alteration of both the basement of the basin and sedimentary infill. The aim of this thesis is to give an overview of the studied area and, with the use of well data, to verify whether the basement does show lateral changes in weathering that could indicate influence of CO2. The results show that the alteration of the basement is unequal, however no relation between the alteration and surface gas flux was found.
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Injection-induced seismicity: statistic and energetic analysis
Vlček, Josef ; Fischer, Tomáš (advisor) ; Horálek, Josef (referee)
Fluid injection into the rock formations represents a valuable analog to study the role of high-pressurized fluids in the seismogenic process. It is carried out in depths up to first thousands of meters in order to increase the permeability of rock formation for better exploitation of hydrocarbons and geothermal energy. The increased fluid pressure results in decrease of the strength of fractures and faults which causes their brittle failure that is observed in the form of microearthquakes and enables imaging of the stimulated rock volume. Besides this positive role, seismicity sometimes increases to the level that can be felt by the population, which can cause concerns about the seismic risk of these industrial operations. Thus, one of the main interests focused by recent studies deals with the maximum earthquake that can be triggered by hydraulic stimulations. I introduce the ratio between the hydraulic energy and released seismic energy, the seismic efficiency of injection, to assess the effect of fluid injection to the seismicity. This parameter is applied to data from two geothermal reservoirs (Gross Schönebeck and Soultz-sous-Forets) and one gas reservoirs (East Texas). We find that for different data sets, the seismic efficiency encompasses a broad range of magnitudes; from about 10-6 to...
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3D seismic interpretation and model of the Schrattenberg fault system in the Valtice area
Hlaváčková, Šárka ; Fischer, Tomáš (advisor) ; Buchta, Štěpán (referee)
3D SEISMIC INTERPRETATION AND MODEL OF THE SCHRATTENBERG FAULT SYSTEM IN THE VALTICE AREA Šárka Hlaváčková Abstract The Schrattenberg normal fault system represents a dominant feature of the western margin of the Vienna Basin. Along with the Steinberg fault, they controlled the sedimentary and tectonic development of the area, and considerably participated in the deposition of the basin fill during a relatively short period of time in the Miocene. A detailed interpretation of the fault system is essential for full understanding of the local basin development and its geological architecture. The oil exploration industry targets mainly the Steinberg and Schrattenberg fault system because of the occurrences of oil and natural gas deposits that are related to the basin tectonics, which forms structural traps sealed by the main fault systems or by minor synthetic or antithetic faults. The thesis presents a geological framework of the Mistelbach block near Valtice at the western margin of the Vienna Basin. Geological interpretation includes also the fault framework modeling with the emphasis on the course of the Schrattenberg fault system. The model was built in the Petrel interpretation software with the use of the principles of the 3D seismic interpretation. In particular, seismic stratigraphy methods, Petrel...
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The geological evolution of the Vienna basin and interpretation of seismic profiles across the western margin of the basin
Hlaváčková, Šárka ; Fischer, Tomáš (advisor) ; Berka, Jiří (referee)
The geological evolution of the Vienna basin and interpretation of seismic profiles across the western margin of the basin Abstract The Vienna basin represents an example of a Neogene pull-apart basin developed between two orogenic systems - the Eastern Alps and West Carpathians. Their different Miocene geodynamic played the key role in opening of the basin. The pull-apart mechanism was significantly influenced by a rotation in the Middle Miocene. This thesis summarize the geodynamic development of the basin with regard to Tertiary evolution of the wider Carpathian - Panonnian area and paleomagnetic description of a rotation of ALCAPA unit. The Lower Miocene basin is superimposed on stack of nappes of the Alpine - Carpathian thrust belt. It was formed as a piggy-back basin on the top of overthrusted nappes. During the Karpathian, a new tectonic settings was established, due to the change of geodynamics within the Alpine - Carpathian area. In the Badenian, the important NE - SW trending faults were developed. The Steinberg and Schrattenberg synsedimentary faults considerably participated in the formation of the west margin of the Vienna basin, and controlled a deposition of the Neogene sedimentary fill, reaching a maximum thickness of 5500 m. In my undergraduate thesis, I target the local development of the...
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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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Historical seismicity and geophysical survey of tectonics in the Cheb area
Hrdličková, Markéta ; Fischer, Tomáš (advisor) ; Horálek, Josef (referee)
This work deals with the documentation of the space-time distribution of seismic activity in the years 1897-1908 in the western Bohemia, using original sources. The region of Vogtland / northwest Bohemia is known as one of the most interesting European regions with the occurrence of earthquake swarms. Seismic catalogs are available for this area only for the last few decades when the seismic stations were in operation. For the earlier period only macroseismic observations are available. The aim of this work is to compile the catalog of earthquakes for the years 1897-1908 with the use of the macroseismic data. This requires estimating the origin time of earthquakes using the distribution of the macroseismic observations in time. First, the original historical materials Mittheilungen der Erdbeben-Commission der kaiserlichen Akademie der Wissenschaften in Wien were compared with geophysical catalog of Vít Kárník Erdbebenkatalog der Tschechoslowakei bis zum 1956, which is a summary of selected data from the original materials. Macroseismic observations from the catalog were digitized in the form spreadsheet tables. It turned out that in most cases the data in the Kárník's catalog represent observations of earthqukes and in isolated cases these are the seismic events themselves. Cluster analysis was...
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Modelling of the low-velocity layer in seismic prospection
Procházka, Jan ; Fischer, Tomáš (advisor) ; Skopec, Jiří (referee)
The subject of the thesis is to compare layered model and tomographic model. These models are used for description of low velocity layer in seismic survey. The goal of the work was to find out the conditions whether to prefer tomographic model instead of layered model. Program Geostar was used for modelling of low velocity layer. This program is a part of software package produced by CGG Veritas company. Geostar is available at department of Applied Geophysics for study purposes. Four synthetic models were created for comparison of tomographic and layered models. Models of low velocity layer were computed for layered an tomographic model in Geostar environment. Original models were compared to created models. Accuracy was estimated on root mean square error and static correction which was exactly known. In all cases, layered model showed better results then tomographic model. 1
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