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PL
Skały karbońskie złożone z piaskowców, mułowców, iłowców i węgli tworzą ośrodek typu warstwowo-szczelinowatego i o ich zdolności do migracji w nim cieczy lub gazów, czyli przepuszczalności lub współczynniku filtracji decyduje obecność w nich szczelin, a nie porowatość ośrodka. Ocena rzeczywistych własności zbiornika warstwowo-szczelinowatego może być zatem dokonana dopiero w badaniach in situ. Jako metodę oznaczenia przepuszczalności oraz współczynnika filtracji skał wykorzystano badania sondą aerometryczną.
EN
Carboniferous rocks composed of sandstone, silt, claystone and coals form a stratified-fracture type medium. So their ability to migrate liquids or gases, such as permeability or filtration coefficient, is determined by the presence of fractures in them, not the porosity of the medium. Therefore, the assessment of the actual properties of the stratified-fractured reservoir can only be made by in situ tests. As a method of determining permeability and rock filtration coefficient, an aerometric probe test was used.
PL
Celem pracy było dobranie i zwalidowanie optymalnej metody analizy zawartości siarki w rdzeniach wiertniczych, w tym pochodzących z pokładów węgla. Ponadto badania zostały przeprowadzone dla rop naftowych. W ramach pracy porównano wyniki badań zawartości siarki metodą analizy elementarnej w dwóch analizatorach: w analizatorze elementarnym EA 1108, który daje możliwość spalania próbek w temperaturze do 1080°C, co nie zawsze jest wystarczające w przypadku próbek geologicznych, oraz w analizatorze Leco CR12 rozbudowanym o moduł do oznaczania siarki, który daje możliwość wykonania analizy w 1350°C. W toku analizy elementarnej następuje przekształcenie siarki wolnej i związanej w dwutlenek siarki SO2, którego zawartość jest mierzona za pomocą różnych detektorów: detektora cieplno-przewodnościowego (TCD) w analizatorze EA 1108 lub detektora podczerwieni w analizatorze Leco CR12. Przed badaniami porównawczymi zwalidowano metodę analizy siarki w analizatorze Leco CR12. Badania porównawcze wykonano dla próbek skalnych, dla węgli i dla rop naftowych oraz dla kerogenu. W ramach pracy przeprowadzono analizy elementarne zawartości siarki dla 23 próbek węgla, 22 próbek skał, 5 próbek kerogenu wydzielonego z tych skał oraz dla 9 rop naftowych. Badane próbki węgla i materiału skalnego pochodziły z rdzeni wiertniczych z otworów poszukiwawczych. Wykazano zgodność stosowanych metod dla kerogenu i dla węgli o zawartości siarki powyżej 0,75% w/w oraz dla rop powyżej 0,3% zawartości siarki. Dużo gorszą zgodność uzyskano dla materiału skalnego z rdzeni wiertniczych, charakteryzującego się dyspersją materii organicznej. Dla próbek o niskiej zawartości siarki bardziej wiarygodnych wyników dostarczają oznaczenia wykonane w analizatorze EA 1108. W przypadku ośrodków o dużej dyspersji substancji organicznej, takich jak warstwy istebniańskie, bardziej wiarygodne są wyniki oznaczeń w analizatorze Leco CR12, ze względu na wielkość próbki analitycznej.
EN
The purpose of the work was to select and validate the optimal method for analyzing sulfur content in drilling cores, including those from coal seams. In addition, research was done for petroleum. As part of the work, the results of sulfur content testing were compared by means of elemental analysis in 2 analyzers: in the EA 1108 elemental analyzer, which gives the possibility of burning samples at temperatures up to 1080°C, which is not always sufficient for geological samples, and in the Leco CR12 analyzer expanded with a module for determination of sulfur, which gives the opportunity to perform the analysis at 1350°C. In the course of elemental analysis, free and bound sulfur is transformed into sulfur dioxide SO2, the content of which is measured by means of various detectors: the thermal conductivity detector (TCD) in the EA 1108 analyzer, or the infrared detector in the Leco CR 12 analyzer. Before the comparative tests, the method of sulfur analysis in the Leco CR 12 analyzer was validated. Comparative studies were carried out for rock samples, for coals, for petroleum and for kerogen. As part of the work, elemental analyses of sulfur content were carried out for 23 coal samples, 22 rock samples, 5 kerogen samples separated from these rocks and for 9 petroleum samples. Tested coal and rock material samples came from drill cores from exploratory wells. The methods used for kerogen and for coals with sulfur content over 0.75 wt % have been shown to be compatible. For oils, compatibility was observed above 0.3% sulfur content. Much worse compliance was obtained for rock matter from drilling cores, characterized by dispersion of organic matter. For samples with low sulfur content, determinations in the EA 1108 analyzer provide more reliable results. For media with a high dispersion of organic matter, such as Istebna Beds, the results of determinations in the Leco CR12 analyzer are more reliable due to the size of the analytical sample.
3
Content available Geoelektromagnetyczne właściwości skał
PL
Istnienie magnetyzmu znane było ludziom od dawien dawna. Zwrócili uwagę na dziwne kamienie przyciągające żelazo. Były to, jak się później okazało, rudy magnetytu. Przed czterema czy pięcioma tysiącami lat w Chinach przy pomocy magnetytu sporządzono pierwszy kompas. W Europie prymitywnymi kompasami zaczęli posługiwać się Wenecjanie w XII wieku. W niespełna sto lat później żeglarze zwrócili uwagę na fakt, iż namagnesowana igła nie wskazuje dokładnie kierunku północnego bieguna geograficznego. W 1492 roku Krzysztof Kolumb podczas swej podróży przez Ocean Atlantycki stwierdził, że odchylenia te są niejednakowe dla różnych punktów globu ziemskiego. Wielu żeglarzy w miarę posuwania się na północ obserwowało coraz większą różnicę między wskazaniami igły kompasu a kierunkiem bieguna północnego.
EN
The Brazilian split test on a centrally holed disc (referred to as a ring-disc specimen) is an important indirect method for determining the tensile strength of rock. This paper studies the effect of the diameter d of the center hole and its position, defined by the eccentricity b and the inclination angle of the eccentric hole, on the peak load, failure pattern and horizontal stress of the disc specimen via laboratory experiments and numerical modeling using the finite element method (FEM). Static Brazilian split tests are conducted on an intact disc and three types of holed discs: C-specimens containing a central hole with different diameters, EH-specimens with a horizontally eccentric hole and ER-specimens with a rotationally eccentric hole.
EN
Nowadays, in order to determine whether given rock properties make it useful for specifi c purposes, the material is examined using relevant test equipment. At the times of Jan Michałowicz, any knowledge in this respect was transmitted by the master to his apprentices, based on the master’s experience. The artist used domestic rock raw materials to sculpt monuments commemorating important persons who were his contemporaries. For the petrographic analysis, the authors selected the most distinguishable works of the artist, which he signed or which are most likely to have been sculpted by him. The authors analysed the materials used by the artist to carve specifi c elements of his works, as well as rock raw materials in terms of their historical and contemporary properties. Consequently, the petrographic study allowed to describe the rocks in greater detail, as well as their properties useful for sculpture purposes, and their durability. Artistic qualities helped determine the sources of stones used by Jan Michałowicz during his projects. These include the quarries near Pińczów (limestone), Kunów (sandstone), Bolechowice (marble), Żurawno (alabaster) and initially quarries in Hungary. The discussed works of Jan Michałowicz provide firm grounds for acknowledging the artist as the leading co-founder to Polish Renaissance art.
EN
Gega lake, in southeastern Tibet, was formed by the blocking of Yarlung Tsangpo gorge by a glacier and is a well-known example of geomorphological damming. However, the evolution of the damming process at the site is still not understood in detail. Here, we use measurements of multiple magnetic parameters of the sediments from the Yusong (YS) 3 section, which is well-dated by optically stimulated luminescence, to provide a detailed history of the late stage of Gega dammed lake since 17.0 ka. Low-frequency field magnetic susceptibility (χlf) increases upwards gradually from 25 to 79 × 10−8 m3/kg above 5.5 m, but other magnetic properties, such as frequency-dependent magnetic susceptibility (χfd % and χfd), susceptibility of anhysteretic remanent magnetization (χARM), and saturation isothermal remanent magnetization (SIRM) did not show a similar degree of enhancement. The magnetic grain size indicators of χARM/χlf, χARM/SIRM, and χlf/SIRM all indicate a trend of increasing magnetic grain size from the 5.5 m to the top of section; however, the bulk sediment grain size decreases gradually within the same interval. The total organic carbon is very low (0.2–0.7%), and thus, it is unlikely that the sedimentary environment is sufficiently strongly reducing to lead to the dissolution of magnetic minerals. Therefore, we infer that the coarsening-upwards of the magnetic grain size, and the increasing magnetic susceptibility from 5.5 m, reflect the gradual preferential preservation of magnetic minerals, caused by the deepening of the lake. Thus, we interpret the magnetic record of the section as reflecting the gradual deepening of the late stage of Gega ice-dammed lake. Last, the abrupt disappearance of the lake may have resulted in an outburst flood.
PL
W artykule przedstawiono analizę wyników badania w mikrotomografie komputerowym sieci spękań w próbkach skalnych, poddanych testom jednoosiowego ściskania. Próbki były skanowane w mikrotomografie komputerowym przed testem, następnie po obciążeniu siłą o wartości 40 – 50% siły niszczącej, a także po osiągnięciu granicy makrodylatancji (lub granicy wytrzymałości). Analiza uzyskanych trójwymiarowych obrazów skanowania pozwoliła opisać w sposób ilościowy morfologię sieci spękań: porowatość, rozkłady przestrzenne szerokości spękań i krętości, a także wskaźnik SMI (ang. structure model index). Znajomość wymienionych wielkości jest przydatna przy określaniu parametrów przepuszczalności badanego materiału.
EN
The paper presents the analysis of crack network development induced in rock samples, subjected to uniaxial compression. The samples were scanned using micro-computer tomography after three stages of load: before loading, after application of a force equal to 40–50% of ultimate limit and, finally, after reaching microdilatancy threshold (or ultimate limit force). The analysis of acquired 3D images at every loading stage included fracture network segmentation and determination of chosen quantities describing its morphology: porosity (fraction of void space), spatial distribution of fracture aperture, tortuosity as well as structure model index (SMI). The parameters can be used to determine permeability parameters of cracked material.
PL
W artykule przedstawiono wyniki testów nanoindentacji przeprowadzone na próbce skalnej. Zastosowano sekwencyjną indentację, tj. autorski program obciążenia próbki. Pozwoliło to obserwować zmienność modułu sprężystości w zależności od skali obserwacji. Wydzielono dwie skale obserwacji, tj. mikro i mezo. Najmniejsza stosowana siła indentacji 0,5 mN prowadzi do odpowiedzi mechanicznej składników tworzących szkielet. Wyniki uzyskane w przypadku najwyższej siły – 500 mN, reprezentują parametr efektywny dla tzw. zastępczej mikrostruktury jednorodnej.
EN
The paper presents results of nanoindentation tests carried out for intact rock specimen. The sequential nanoindentation is used and the novel loading schedule, for prescribed tip position, is applied. It enables us to identify the mechanical morphology at different observation scales. Two scales were identified, i.e., micro- and meso-scale. The lowest value of indentation force, 0.5 mN, provides the mechanical response of the constituents forming the skeleton. The results obtained for the highest value of indentation force, 500 mN, represent the effective property for the so-called „equivalent” homogeneous microstructure.
10
Content available remote Hydrofobizacja strukturalna metodą iniekcji materiałów drobnoporowatych
PL
W artykule zaprezentowano wyniki badań dotyczących możliwości hydrofobizacji skał wapiennych metodą iniekcji. Omówiono zagadnienia dotyczące hydrofobizacji jednej ze skał wapiennych – opoki wapnistej.
EN
The article presents the results of studies of water repellent capacity of limestones applied through injection. The aspects of hydrophobization are discussed for one type of limestone, namely calcareous bedrock.
EN
Rubbers are interesting materials and are extensively used in many mining industries for material transportation. Wear of rubber is a very complex phenomenon to understand. The present study aims to explain the influence of rock properties on wear of M and SR grade rubber used in top cover of conveyor belts. Extensive laboratory experiments were conducted under four combinations of normal load and sliding speed. The wear of both the rubber types were analyzed based on the rock properties like shear strength, abrasivity index and fractal dimension. A fully instrumented testing set up was used to study the wear of rubber samples under different operating conditions. In general, wear was higher for M grade rubber compared to SR grade rubber. Increase in shear strength of rocks depicts decreasing trend for the wear of M and SR grade rubber at lower load conditions. Moreover, a higher load combination displays no definite trend in both the rubbers. The strong correlation between the wear of rubber and frictional power for all rubber-rock combinations has given rise to the parameter A, which reflects the relative compatibility between the rubber and rock. Increase of Cerchar’s Abrasivity Index of rocks shows gradual enhancement in wear for M grade rubber in all the load and speed combinations whereas, it fails in SR grade rubber due to its higher strength. The wear of rubber tends to decrease marginally with the surface roughness of rocks at highest normal load and sliding speed in M grade rubber. However, the wear of M and SR grade rubber is influenced by the surface roughness of rocks.
EN
Hydraulic fracturing of rocks boosts the production rate by increasing the fracture-face surface area through the use of a pressurized liquid. Complex stress distribution and magnitude are the main factors that hinder the use of information gathered from in situ hydraulic fracturing in other locations. Laboratory tests are a good method for precisely determining the characteristics of these processes. One of the most important parameters is breakdown pressure, defined as the wellbore pressure necessary to induce a hydraulic fracture. Therefore, the main purpose of this investigation is to verify fracture resistance of rock samples fractured with the assistance of the most popular industry fluids. The experiments were carried out using a stand designed specifically for laboratory hydraulic fracturing. Repeatable results with a relative error within the range of 6-11% prove that the experimental methodology was correct. Moreover, the obtained results show that fracturing pressure depends significantly on fluid type. In the case of a water test, the fracturing pressure was 7.1±0.4MPa. A similar result was achieved for slickwater, 7.5±0.7MPa; however, a much lower value (4.7±0.5MPa) was registered in the case of carbon dioxide.
PL
Szczelinowanie hydrauliczne polega na niszczeniu skały za pomocą płynu pod wysokim ciśnieniem w celu zwiększenia powierzchni spękań, co poprawia wydajność produkcyjna. Rozkład naprężenia w górotworach i jego wielkoś jest zwykle relatywnie skomplikowana, a to utrudnia wykorzystanie informacji zgromadzonych w trakcie procesu szczelinowania w innej lokalizacji. Przy tym zwykle prace prowadzone są na dużym obszarze, a znaczna część instalacji znajduje się pod ziemią. W efekcie wiedza na temat warunków, w których przeprowadzono proces jest zwykle ograniczona. Dlatego próby laboratoryjne stanowią dobrą metodę weryfikacji parametrów procesu. Jedną z najistotniejszych wielkości jest ciśnienie szczelinowania niezbędne do wytworzenia spękań. Decyduje ono zarówno o parametrach instalacji szczelinującej jak i ma wpływ na aktywność sejsmiczną obszaru. W literaturze istnieją wzory pozwalające szacować wielkość ciśnienia szczelinującego, jednak nie uwzględniają one roli płynu szczelinującego. Najpopularniejszym medium szczelinującym stosowanym w przemyśle jest woda, często domieszkowana specjalnymi dodatkami redukującymi tarcie. W górotworach o szczególnie zwartej budowie stosuje się zwykle ditlenek węgla lub azot. Dotychczasowe badania nad wpływem płynu szczelinującego na wielkość ciśnienia miały ograniczony charakter. Ze względu na ten fakt praca podejmuje to zagadnienie.
EN
This paper presents the problems associated with the rapid change of the rock stress-strain state in terms of increasing the rate of coal mining. Parameters of the roof collapse are determined depending on the rate of a longwall advancing under conditions of poor rocks. Statistical data are processed to obtain a general trend concerning the mining rate impact on the roof collapse. The statistical strength theory is applied to explain the increase in mined-out space and the size of hanging roof behind a coal face. Numerical simulation is carried out to determine a critical size of mined-out space that provokes a roof collapse. The area of yielded rocks is outlined using the criterion developed taking into account the rate of longwall advancing. A general regularity is obtained to determine the roof collapse parameters. The developed technics gives a possibility to predict the moment of general roof collapse at the initial stage of longwalling to prevent the negative effect of the rapid stress redistribution provoking joints propagation and intensive gas release. The estimation of the rock stress-strain state considering the rate of mining operations can be useful for tasks related to a new technology implementation. The statistical strength theory and failure criterion applied together provides adequate planning of mining activities and the assessment of natural hazards.
14
Content available A model study to measure fragmentation by blasting
EN
Accurate measurement of blast fragmentation is important in mining and quarrying operations, to monitor blasting and optimize blast design. A new digital photoanalytical method to measure the size of fragments by using FragScan system is presented here. Photographs of the broken rock are digitized, and individual measurement, based on mathematical morphology techniques, achieves, within successive openings on a binary image, a numerical sieving. The method was tested during recent full scale blasting tests in the case of open pit gold mine of Amesmessa (Algeria). It shows great potential as a practical aid to predicting, monitoring, and controlling the quality of the fragmented rock.
16
Content available remote Second occurrence of the new mineral harmunite CaFe2O4, Negev Desert, Israel
EN
Harmunite (ideally CaFe2O4) was found in the natural environment for the first time in 2014 in pyrometamorpic larnite rocks of the Hatrurim Complex that lies near Jabel Harmun – moutain located in Judean Desert, Israel – from which it derives its name (Galuskina et al. 2014). Macroscopically, together with srebrodolskite and magnesioferrite, harmunite creates black porous aggregates (Galuskina et al. 2014). In reflected light with crossed polars it has light gray colour with characteristic red internal reflections (Galuskina et al. 2014). Harmunite occurs as crystal faceted by the simple forms {100}, {110}, {210}, {011}, {001}, and {010} or as rounded fragments (Galuskina et al. 2014). The structure of CaFe2O4 consist of double rutile-type ∞1[Fe2O6] chains, which are further linked by common oxygen corners creating a tunnel-structure with large trigonal prismatic cavities occupied by Ca along [001] (Galuskina et al. 2014). Synthetic compound CaFe2O4 is known and used as ceramic material and pigment, semiconductors, refractories, thermally stable material and others (Candeia et al. 2004, Kharton et al. 2008). This phase was also previously found in the Salair pyrometamorphic complex of Kuznetsky coal basin in south-west Siberia, Russia (Nigmatulina & Nigmatulina 2009) and Chelabynsk coal basin, Southern Urals, Russia (Chesnokov et al. 1998) and described as “aciculite”, but it was not approved as a mineral due to its anthropogenic origin (Galuskina et al. 2014). We found harmunite in pyrometamorphic gehlenite rocks of the Hatrurim Complex located in north-east part of Negev Desert, Israel. As for the holotype specimen, it forms aggregates with srebrodolskite and Mg – ferrite. Single grains of harmunite from Negev reach about 25 μm in size. In comparison with holotype specimen, this harmunite contains more varied substitution at octahedral site, where Fe3+is substituted by Cu, Ni or Zn. Futhermore, there is no Al, which was noted in holotype harmunite. The Raman spectrum of harmunite from Negev is similar to spectrum of holotype specimen and of the synthetic analog. The main Raman bands of harmunite from Negev are as follows (cm–1): 1241, 648, 601, 526, 439, 376, 301, 277, 214, 166, 131, 91.
EN
Deformation bands and microfractures occurring in sandstones affect the petrophysical properties of the rock and determine fluid flow. Deformation bands are quasi-tabular structures, up to 5 mm thick that accommodate offsets on the order of a few centimeters (Fossen 2010). Such bands show different petrophysical properties in relation to the surrounding rocks and may function as either a path or a barrier to the migrating fluids (Antonellini et al. 1994, Fossen 2010). High porosity rocks show commonly low permeability due to the presence of deformation bands. Recognition of such relationships is important in petroleum geology, particularly for proper reservoir characterization (e.g. Fossen et al. 2007, Ballas et al. 2012, 2013). The aim of the study is to identify and to characterize deformation bands occurring in flysch sandstones of the Outer Carpathians using X-ray nanotomography and nuclear magnetic resonance (NMR). Moreover, the impact of sample size on obtained results was also studied. For this study, samples of medium-grained arenites showing catalclastic deformation bands have been collected from the lower Krosno Beds of the Silesian Nappe. Permeability of the studied samples measured along deformation bands and in perpendicular direction varies significantly, being 0.13 mD and <0.001 mD, respectively. Analyses were conducted using X-ray nanotomography Nanotom S General Electric. The recorded data were processed and analyzed using ImageJ and myVGL software. The NMR measurements were carried out on water-saturated samples using the 2MHz Magritek Rock Core Analyzer and 24MHz Tomography System. The pore size distribution (PSD) of the rock sample was determined precisely by T2CMPG experiments. The spatial estimation of the deformation bands achieved from T2 spatially resolved measurements. Complementary data regarding to band geometry was registered using three-dimensional Single Point Imaging (SPI) (comp. Zhang & Blümich 2014). Cylindrical plugs38 mm high and 25 mm in diameter were analysed. The same plugs were used for permeability measurements. The X-ray nanotomography measurements were carried out in three resolutions. The first measurement was carried out with a resolution of 4.2 microns, but the resultant images were difficult to interpret. Therefore, successive analyses were performed with a resolution of 20 microns covering the entire volume of the samples. After locating microstructures samples were X-rayed again with a resolution of 2.1 microns. In sections obtained at a resolution of 4.2 microns, fine structure attributable to deformation band reveals parallel grain orientation and higher density compared with the host sandstone. We observed a slight offset along deformation bands. Three-dimensional image of the sample obtained at a resolution of 20 microns determined the geometry of tectonic microstructures. In one of samples, two structures were recognized. One of them was oriented parallel to the axis of the core, the other was inclined at an angle of about 60 degrees. The thickness of deformation band visible in the cylindrical plug was much larger (2 mm) than the thickness of the surface obtained by visualization. This was due to the presence of microfractures, which formed along the deformation band. Measurement with a resolution of 2.1 microns took an upper base of the cylindrical plug. Two thin fractures and one relatively thick fracture (approx. 0.2 mm) were distinguished. This indicates that the deformation band visible on the surface of the core passes into the microfracture within the sample. It was also confirmed by the visualization with a resolution of 20 microns. Determination of porosity and permeability of the sandstone using the X-ray nanotomograph was impossible due to small pore size that the device is not able to register. However, visualization made with a resolution of 20 microns allowed to clarify the reasons for the different measurements of permeability. Increase of the permeability in the direction parallel to the axis of the core is caused by the presence of open microfractures. The NMR results confirmed possibility to visualize geometry of the bands and their influence for the spatial distribution of porosity. The results show that too large sample sizes make impossible to perform the analysis with high resolution. According to Rodrigues et al. (2015) sample dimensions of 15 × 10 × 10 mm are sufficient to determine the porosity of deformation bands. Published results on three-dimensional micro-tomography of deformation bands concern aeolian sandstones showing high mineralogical and textural maturity (Rodrigues et al. 2015). In contrast, studied flysch sandstones show large diversity of their mineral composition. Therefore, visualization of microtectonic deformation hosted in these sandstones is more difficult to interpret.
PL
W artykule przedstawiono wyniki modelowania numerycznego rozkładu naprężeń i przemieszczeń górotworu na skutek oddziałania naprężeń termicznych w trakcie prowadzenia procesu podziemnego zgazowania węgla, wykonanego w programie FLAC3D, opartym na metodzie różnic skończonych. Obliczenia numeryczne przeprowadzono w dwóch wariantach − nie uwzględniając zmian parametrów geomechanicznych na skutek oddziaływania temperatury oraz po ich uwzględnieniu (na podstawie badań laboratoryjnych). Wyniki badań wykazały, że można uwzględnić zmiany właściwości geomechanicznych skał w zależności od działającej na nie temperatury, a tym samym dokładnie odwzorować proces podziemnego zgazowania i jego oddziaływania na stan naprężeń i przemieszczeń wokół komory reaktora. Uwzględnienie zmian parametrów geomechanicznych miało znaczny wpływ na obliczany stan naprężeń i przemieszczeń górotworu.
EN
This paper presents the results of numeric modelling of the ground stress and displacement distributions within a rock mass, caused by thermal stressing during underground coal gasification. The inputs for the model were the laboratory experimentation results obtained for geo-mechanical properties of rock around a reactor with a predefined geometrical form. The calculation inputs included the results of tests of mudstone characterised by low compression strength for mono-axial compression (in air-dry state), and medium-grained sandstone with moderate compression strength, with both rock types sampled from the Chwałowice basin deposits. The rock samples were heat treated at temperatures between 100 and 1200°C and had the following parameters determined: resistance to mono-axial compression and Young’s modulus. The numerical calculations were processed using the FLAC3D software suite by the finite difference method. There was a total of two numerical calculation variants: (1) without and (2) with changes in geo-mechanical properties caused by temperature (from the laboratory research), for two lithological systems. The modelling investigation results have proven that it is feasible to consider changes in rock geo-mechanical parameters in relation to the temperature acting on the rock, and thus to precisely represent the process of underground gasification and its effects on the stresses and displacement around the gasification reactor chamber. The inclusion of the changes in geo-mechanical parameters had a significant effect on the calculated stresses and displacement of the rock mass.
PL
Żyjemy w bardzo egocentrycznej rzeczywistości. Dla większości z nas kreatywne okazuje się to, co jest nowe, inne, a spektakularne to, co nas wyróżnia z tłumu. W czasach, gdy zaczyna nam doskwierać brak autentyczności, można by zadać pytanie, co jest bardziej wartościowe: kontrowersyjna przestrzeń krzycząca nazwisko projektanta czy miejsce, gdzie kończy się ingerencja człowieka, a zaczyna natura? Gdzie nawet nie przyjdzie do głowy pytanie o artystę, ale odnajdziemy to, czego w głębi duszy potrzebujemy najbardziej, a więc autentyczności, spokoju i harmonii.
EN
During burial, sediments and rocks undergo physical and chemical changes due to temperature and pressure growth. All these processes are known as diagenesis (Boggs 2009). These changes play an important role in postedpositional modification of reservoir parameters, such as porosity, permeability and filtration. Primary porosity of rock may be reduced by cement precipitation, mechanical compaction, mineral reactions or pressure solutions, and moreover increased (secondary porosity) during burial, as a result of grain and cement dissolutions, mineral reactions or fracturing (Bjorlykke 1983). Permeability is controlled mainly by pore-throat size (Pittman 1992) and its loss corresponds to the decreasing volume of primary porosity (Pittman 1992, Dutton & Loucks 2010). The aim of presented work was investigation of diagenetic changes within deeply buried tight Rotliegend Sandstones from Polish part of Southern Permian Basin and their impact on reservoir properties of rocks. For the research were selected 26 core samples from 16 wells and depth interval 3439.8-4284.7 m. All wells are located within the aeolian sediments of Eastern Erg (central part of Polish part of Permian Basin). Samples are represented by medium - and fine - grained quartz arenites and wackes. Qualitative examination of samples included petrographic analysis of thin sections in polarizing microscope in transmitted light and scanning electron microscopy. Numerical characterization of pore space was obtained during petrophysical analysis on 11 samples, usingmercury porosimetry. Diagenetic processes strongly amended reservoir parameters of rocks. The greatest impact on the decrease of primary porosity had mechanical compaction. It resulted in the development of long grain contacts. As the main cement component were identified clays, with subordination of carbonate, ferruginous and anhydrite minerals. Porosity of analyzed samples does not exceeded 6%, permeability - 0.1 mD. Reservoir properties of Rotliegend Sandstones were affected by diagenesis, forced by temperature and pressure growth during burial. Primary porosity of sandstones was decreased by mechanical compaction and cement precipitation. Observed evidence of secondary porosity was created due to dissolution of less stable minerals - feldspars. Precipitation of authigenic clay minerals also highly reduced permeability and filtration of sandstones.
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