Dissertations / Theses on the topic 'Clay-Shale'

Master of Science
Geology
Sambhudas Chaudhuri
Chemical and mineralogical compositions of < 2 µm-size fraction clays of the shale source rocks of Devonian-Mississippian age in northern Oklahoma were determined to find any link between the minerals and the generation of petroleum. Ten samples of clay separates were analyzed for their mineral composition, major element contents, K/Rb ratios, and REE contents. XRD analyses and SEM showed the presence of discrete illite, the most dominant clay mineral, with smaller amounts of mixed-layer illite/smectite, chlorite, and kaolinite. The non-clay minerals found in the Woodford Shale from this study include quartz, dolomite, calcite, pyrite, feldspar (albite and microcline), and apatite. The clays in these rocks have a range of K/Rb ratios between 160 and 207. These ratios are considerably lower than the ratios of average silicate minerals (clays), with expected ratios between 250 and 350. It could be that clays received K and Rb from a solution, which was partly involved in oil generation by which oil received more K relative to Rb making the aqueous phase depleted in K/Rb ratios (Alvarez, 2015). Thus, the low K/Rb ratios for these clays may be reflecting signatures of reactions involving oil generation. The total REE contents ranged between 13 and 30 ppm. The low total REE contents of < 2 µm-size fraction clays in the Woodford Shale as compared to average sedimentary rocks which may be represented by values given either PAAS 184 ppm or NASC with 178 ppm, may suggest that the formation of the clays was linked to oil generation, having known of the face from the study of Alvarez (2015) that crude oils could have higher specific REE concentrations than the associated formation waters. PAAS-normalized REE patterns for these samples display positive Gd anomalies. Two out of the ten samples had prominent Ce anomalies. Only three out of ten samples had Eu positive anomalies, one of which was quite prominent. All samples had MREE enrichment, superimposed on either a flat REE distribution patterns with enrichment in LREE. Only one pattern showed the distribution with a distinct HREE enrichment. The MREE anomalies could be from the effect of phosphate mineralization. In fact, the X-ray diffraction patterns of random powder samples showed the presence of fluorapatite and chlorapatite in most of the studied samples. The total organic carbon (TOC) contents of the whole rocks ranged from 0.5 to 6.54 wt.%. Thus, it can be concluded that hydrocarbon generation potential of the Woodford shale (0.8-4.44 wt.%) is significantly higher than Mississippian Lime unit (0.5 wt.%). Only one sample, which belonged to pre-Woodford Shale Hunton group, had the highest value of TOC. The available K-Ar dates of < 2 µm-size fraction clays suggest that the clays are authigenic (illites) for at least some samples. The dates ranged from 318.6 ± 7.9 Ma (Serpukhovian) to 353.9 ± 7.9 Ma (Tournaisian). All dates are younger than the times of deposition of the Woodford Shale. Assuming there is a genetic link between formation of authigenic illite and hydrocarbon generation, this study suggests that oil generation may have taken place on an average about 30 Ma after the deposition of the Woodford Shale.

High total organic carbon (TOC) and low clay content are two criteria to identify the "sweet spots" in shale gas plays. Recently, machine learning has been proved to be effective to estimate TOC and clay from well loggings. The remaining questions are what algorithm we should choose in the first place and whether we can improve the already built models. Automatic machine learning (AutoML) appears as a promising tool to solve those realistic questions by training multiple models and compares them automatically. Two wells with conventional well loggings and elemental capture spectroscopy are selected from a shale gas play to test the AutoML's ability in TOC and clay estimation. TOC and clay content are extracted from the Schlumberger's ELAN interpretation and calibrated to cores. Generalizability is proved in the blind test well and the mean absolute test errors for TOC and clay estimation are 0.23% and 3.77%. 829 data points are used to generate the final models with the train-test ratio of 75:25. The mean absolute test errors are 0.26% and 2.68% for TOC and clay, respectively, which are very low for TOC ranging from 0-6% and clay from 35-65%. The results show the AutoML's success and efficiency in the estimation. The trained models are interpreted to understand the variables effects in predictions. 235 wells are selected through data quality checking and feed into the models to create TOC and clay distribution maps. The maps provide guidance on where to drill a new well for higher shale gas production.
Master of Science
Locating "sweet spots", where the shale gas production is much higher than the average areas, is critical for a shale reservoir's successful commercial exploitation. Among the properties of shale, total organic carbon (TOC) and clay content are often selected to evaluate the gas production potential. For TOC and clay estimation, multiple machine learning models have been tested in recent studies and are proved successful. The questions are what algorithm to choose for a specific task and whether the already built models can be improved. Automatic machine learning (AutoML) has the potential to solve the problems by automatically training multiple models and comparing them to achieve the best performance. In our study, AutoML is tested to estimate TOC and clay using data from two gas wells in a shale gas field. First, one well is treated as blind test well and the other is used as trained well to examine the generalizability. The mean absolute errors for TOC and clay content are 0.23% and 3.77%, indicating reliable generalization. Final models are built using 829 data points which are split into train-test sets with the ratio of 75:25. The mean absolute test errors are 0.26% and 2.68% for TOC and clay, respectively, which are very low for TOC ranging from 0-6% and clay from 35-65%. Moreover, AutoML requires very limited human efforts and liberate researchers or engineers from tedious parameter-tuning process that is the critical part of machine learning. Trained models are interpreted to understand the mechanism behind the models. Distribution maps of TOC and clay are created by selecting 235 gas wells that pass the data quality checking, feeding them into trained models, and interpolating. The maps provide guidance on where to drill a new well for higher shale gas production.

A multicomponent study of Pb and Cu retention was performed using a selective contamination technique. Soil components were selectively extracted from a multicomponent illite clay artificial soil using extractants commonly utilized in sequential extraction studies. Pb and Cu retention by the soil components: carbonates, amorphous oxides, natural organic matter and the clay minerals, were examined. It was found that the clay minerals are the most important contributor to the retention of Pb and Cu, which in this case is predominantly illite. Adsorption and not precipitation is believed to be the controlling mechanism of retention although retention by precipitation increased with increasing pH.
Pb and Cu retention from a single metal solution as well as competitive retention of Pb and Cu from a mixed metal solution on each of the untreated and treated artificial soils were examined. Competitive adsorption experiments found that Pb was preferred over Cu for adsorption by the untreated and treated artificial soils and greater quantities of Pb were retained than Pb applied in composite with Cu or Cu applied as a single metal. Pb removed from the artificial soil, using sequential extraction analysis, was compared to Pb retained and mass balance was observed.
The artificial soil was found to contain both variable and constant charge surfaces but the artificial soil contaminant interaction was modelled best using only the variable charge surface. The presence of ion exchange adsorption and Ca competition are examined.

Commonly the thermal maturity of the Late Devonian to Early Mississippian Woodford shale found on the flanks of the Arbuckle Mountains of Oklahoma is determined by vitrinite reflectance, values ranging from 0.3-1.5%. Using phyllosilicate minerals, specifically diagenetic mixed layer illite/smectite and diagenetic illite, an understanding of the extent and processes leading to the thermal maturation may be developed. Analysis by XRD of the clay mineralogy of the Woodford shale found kaolinite and mixed layer illite/smectite with <5% smectite and R≥3 stacking order. Modeling of the Woodford shale also suggests the percentage of smectite present in mixed layer illite/smectite to be <5% and commonly <2.5%. Deconvolution of the illite (001) peak supports the low smectite content and high illite crystallinity. The long range ordered illite, R≥3, and high illite crystallinity values are indicative of diagenesis to anchizone conditions suggesting a higher thermal maturity relative to previously measured values of vitrinite reflectance.

Depleting oil reserves and increased costs of the oil and gas recoveries have created the need to drill in challenging formations. When drilled through, shale formations in particular always generated a wide variety of problems if conventional water-based muds are used. Furthermore, the complexity and variations in shales have compounded the task of developing suitable drilling fluids. In light of these problems, the study of shale properties and their interactions with fluids will continue to be a muchneeded source of information in drilling industry. In this study a low molecular weight quaternary amine compound, which is provided by KarKim Drilling Fluids Inc., and its mixtures with sodium and potassium chloride is investigated in the aspects of capillary suction times, hot rolling recoveries, methylene blue capacities and one-dimensional free swelling properties in order to compare performances of salts and amine compound. For all test methods quaternary amine concentration from 1% to 6% by volume were studied and seen that less amount of quaternary amine compound is needed in order to obtain close shale recoveries and shale volume change potential if compared with sodium and potassium chloride. This prevents the usage of high concentration of chlorides and hence provides environmental sensitiveness. Furthermore, it was concluded that combining an amount of salt with quaternary amine compound gives the system enhanced shale inhibition properties.

In the framework of Geotechnical Engineering and Rock Mechanics many cases are known (described in either the classical or the modern tunnelling bibliography) where, even during construction, large deformations and high stresses in the lining are observed. This is the result of natural phenomena identified with swelling and/or squeezing conditions. This thesis is devoted to the study of tunnelling in difficult conditions, with particular attention to the development of large time-dependent deformations. These deformations may develop either during the construction stage, causing instabilities of the tunnel face and unsafe working conditions, or remain hidden during the “short-term”, thus leading to complex problems when the tunnel is put into service. Under these circumstances the construction costs may rise due to the delays in excavation time, the stabilising and heavy support measures to install. Though the physic-chemical reactions which are the basis of these phenomena have been studied for nearly one century, during the last thirty years the research work concentrated on the rigorous identification, quantification and prediction of the models of behaviour associated with them. In particular, during the last few years, two Research Programmes on these topics (“Tunnelling in difficult conditions” and “Mechanised excavation of tunnels”, co-ordinated by Professor Giovanni Barla) were carried out with the financial support of the Italian Ministry for University and Research. Into this contest, a Ph. D. thesis [Barla M., 1999] was dedicated to the determination of the typical stress-paths around a tunnel and the application to laboratory testing by means of a newly developed triaxial cell (Soft Rocks Triaxial Apparatus, SRTA). The samples of a stiff clay came from the Caneva-Stevenà quarry, near Pordenone (Italy), where swelling induced deformations and instabilities caused failure of the 30 cm thick unreinforced concrete lining of the adits. The decision to further investigate these phenomena came from the growing world-wide interest on the subject and from the availability of a new relevant case study. Several cubic samples of tectonized clay shales (Chaotic Complex) were, in fact, obtained at the face of Raticosa tunnel and Osteria access adit, along the new high speed railway line Bologna-Florence. The present study deals with the models of behaviour which were proposed in recent years, with the aim to identify the most significant factors involved in the selection and design of stabilizing measures of the tunnel face and supports to be installed along the heading. The testing programme performed on the clay shales had the task of identifying similarities and/or differences with respect to the previous research. Moreover, the characterisation studies performed allowed for the determination of significant influence of expandable minerals, complex structure and low mechanical properties of these geomaterials. The testing programme included triaxial tests performed on natural material in closely controlled conditions; oedometer type tests were performed on reconstituted samples. The SRTA was modified for the purpose of testing the new material. Other characterization tests (Atterberg limits, X-ray diffraction analyses, oedometer tests on natural material, etc.) were performed in other laboratories (Enel-Hydro, Milan and Seriate). An extended and critical bibliographic study was carried out with the intent of describing the principal available methods for modelling and predicting the swelling behaviour and their consequences. Though several methods are presently available in literature, they are often very specific and effective for particular case studies. Moreover, the models of swelling behaviour are often embedded in relatively simple elastic and elasto-plastic constitutive laws, which do not allow one to take into account time-dependent deformations. Further investigation in the field of advanced models was carried out, with the intent of determining the significant factors influencing the real mechanical behaviour. The second part of this study was devoted to the numerical modelling at the sample scale and at the tunnel scale. Numerical analyses were performed by the Finite Difference Method and an axi-symmetric coupled model reproducing the sample behaviour at laboratory scale. The stress-paths of the triaxial tests reproduced the behaviour of a point located on the tunnel sidewalls during construction with initial isotropic state of stress. Three elasto-plastic laws were assumed for the ground: Drucker-Prager, modified Cam Clay and Nova-Lagioia model [Nova & Lagioia, 2000]. The stress-strain curves obtained from the laboratory tests could be represented in a satisfactory way, but the corresponding excess pore pressure at low stress level (positive) or at incipient failure (negative) could not be predicted reliably. Since any attempt of reproducing the tectonized clay shales behaviour by means of either simple or more complex elasto-plastic models has been shown to be not effective, an alternate way for the purpose of modelling was represented by time-dependent models of visco-elastic plastic type. Considering that the clay shales exhibit at low stress level a significant time-dependent response, the visco-elastic plastic Burgers’ model with Mohr-Coulomb yield criterion (CVISC) as available with the FDM code Flac [Itasca, 1999] was used. The parameters describing the time-dependent response of the specimens (as evidenced during the laboratory tests) were determined by means of closed-from solutions (Burgers’ visco-elastic model) and numerical analyses with the CVISC constitutive equation. In both cases a satisfactory description of the mechanical behaviour could be achieved. Numerical analyses were performed with the intent of reproducing the deformational response of the Raticosa tunnel, for which monitoring data were available (radial and longitudinal displacements). Numerical analyses were performed by the FDM and an axi-symmetric coupled model reproducing the full excavation sequence of an equivalent circular tunnel. The geotechnical parameters entering the CVISC model for the clay shales at the tunnel scale needed to be assessed in terms of the parameters obtained at laboratory scale. In fact, the parameters based on laboratory testing were not likely to reproduce the tunnel behaviour as observed during excavation. This was the case for deformability, strength, and time dependent parameters, which were evaluated on the basis of experience and in situ observations. The tunnel response in terms of plastic zone extension, radial and longitudinal displacements versus time could be reproduced satisfactorily. Based on of the present work, the following conclusions can be drawn: (a) the time-dependent behaviour of the clay shales is a significant factor to be taken under close consideration for the assessment of the tunnel response to excavation (the elasto-plastic constitutive laws are not capable of reproducing the full range of behaviour of the tunnel); (b) laboratory testing is necessary in order to determine the relevant features of the mechanical behaviour of the material, however the parameters determined from laboratory tests cannot be directly used for appropriate prediction of tunnel behaviour; (c) monitoring is essential for the assessment of the tunnel response (stability of the face and of the core ahead of the face), including the effectiveness of the stabilization measures and of the primary lining, and the time of its installation.

This work provides an insight into how the molecular interactions influence macroscale properties of two materials: swelling clay and oil shale. Swelling clays cause enormous damage to infrastructure: buildings, roads, and bridges. Understanding the mechanisms are essential to prevent the detrimental effects and use of these clays for engineering applications. Our group studied the effect of fluid polarity on sodium montmorillonite (Na-MMT) swelling clay mineral using molecular modeling and experiments for bridging the molecular level behavior with the microstructure, swelling pressure, permeability, and compressibility. Various polar fluids (Dielectric Constant 110 to 20) found in landfill leachates are used. Our molecular dynamics (MD) simulations show that the nonbonded interactions of Na-MMT with polar fluids are higher than with low and medium polar fluids. These results are consistent with the results from Fourier transform infrared (FTIR) spectroscopy experiments. The polarity of the fluids and the fluid content influence the interlayer spacing, interlayer modulus, nonbonded interactions, and conformation as well as the shear strength parameters, the angle of internal friction (φ) and cohesion (c). Furthermore, the unconfined compressive strength experiments are used to evaluate the undrained cohesion at various swelling level. The nanomechanical properties, the modulus of elasticity (E) and hardness (H), of the undisturbed dry and saturated Na-MMT at various level of swelling are evaluated using nanoindentation experiments for the first time. The undrained cohesion, modulus of elasticity, and hardness decrease with increase in swelling level. Swelling controls the microstructure of Na-MMT clay, and the clay particles breakdown into smaller sizes with increase in swelling level. The Green River Formation located in the United States is the richest oil shale deposit in the world. Oil shale contains clay minerals, bitumen, and kerogen—a precursor to crude oil. A three-dimensional (3D) kerogen model is built from seven fragments, and the interactions of kerogen with Na-MMT is investigated using MD simulations to understand how the kerogen is bound to the clay mineral. The nonbonded interactions between Na-MMT and kerogen as well as among kerogen fragments are found. This work seeks to develop new methods to extract kerogen economically and efficiently.
Department of Energy (DoE)
Mountain Plains Consortium (MPC)
North Dakota Established Program to Stimulate Competitive Research (ND EPSCoR)

Refractory aggregate manufactured from common clays, claystones and shales in Czech Republic are mostly classified as fireclay. For specific applications are these grogs not suitable and there is a need to use grogs with higher content of alumina oxide. Theoretical part of this thesis is focused on the mineral mullite, which is one of the basic minerals in Al2O3 - SiO2 system. Research is focused on methods of mullite production, manufacture of recfractory grog and new possibilities in modification of current raw materials. In experimental part is carried out a verification of possible production of grogs with increased alumina content according to the designed composition.

Les argiles se déforment selon trois mécanismes principaux; (1) plasticité à l'échelle sismique (plis et failles), (2) fluidisation (volcanisme de boue), et (3) déformation ductile / plasticité (distribuée spatialement), ce qui peut imiter la déformation du sel sous contrainte. La ductilité de ces deux roches est régie par des processus se déroulant au-delà de «l’échelle d’observation» (e.g. plasticité cristalline et pression solution pour le sel, bandes de cisaillement, plis et failles pour l’argile) impliquant une «déformation distribuée». Certains facteurs de contrôle tels que la pression de confinement, la température, la teneur en eau, le taux de chargement et la quantité de sédimentation, définissent le comportement ductile de ces roches. Lorsque ces facteurs de contrôle sont satisfaits, les roches ductiles (e.g. le sel et l’argile) présentent une similitude comportementale avec les matériaux visqueux (par exemple les fluides) dans la nature et leur signature spécifique liée à la déformation (e.g. halocinèse, argilocinése) peut être enregistrée dans le paquet sédimentaire entourant ces formations des roches.Cependant, le modèle de mobilisation des argiles et donc la tectonique argileuse n'est pas encore aussi bien identifié que pour le sel en raison de la mauvaise qualité des données de subsurface acquises (sismiques) et du manque d'exemples d'affleurements bien préservés. Même si certaines structures décrites comme des «diapirs», des «caractéristiques de la canopée», des «minibasins» et des «welds» ont été enregistrées par la couverture sédimentaire environnante dans certains cas naturels et rapportées par les chercheurs; contrairement au sel, aucune remarque concluante de ce type n'est proposée sur le thème de la mobilité des argiles. Dans cette étude de doctorat, nous avons travaillé sur un ensemble de données sismiques 3D de haute qualité bien imagées et avons cherché à faire une analyse géométrique de la déformation dans un système sujet à la tectonique argileuse (le bassin de sous-Ceduna situé dans le bassin de Great Bight, Australie) afin d’illustrer les analogies avec la tectonique salifère. L'objectif principal était de montrer l'importance de la mobilization argileuse et son impact sur le développement structural et de proposer un scénario cinématique pour l'ensemble du système deltaïque (White Pointer Delta) enfoncé au-dessus d'un niveau de détachement de l’argile épais (formation Blue Whale). Suite à nos recherches, nous en sommes venus à montrer que:- À grande échelle, les argiles présentent un modèle de déformation plastique et se comportent comme un fluide de manière visqueuse imitant les dépôts de sel, dont la signature de déformation peut être enregistrée par les strates de sédiments entourant ces restes de l’argile (argilo-cinèse).- D’un point de vue technique, nous observons des structures telles que les ‘wedges’, les ‘welds’, les ‘minibasins’ classique de la tectonique salifère: le delta en glissement et étalement montre une evolution depuis la chaine de deformation par plis et chevauchement vers un duplex de chevauchement, ce qui suggère un changement rhéologie de l’argile, évoulant par du durcissement qui favorise la location de la déformation. - Localement, dans la zone étudiée du sous-bassin de Ceduna, les argiles montrent une mobilization par fluidization, formant des volcans de boues. Nous avons proposé que le mécanisme de duplexation favorise l'initiation de la mobilité fluide de l’argile au-dessus des structures de ‘down-building’.Il est de la plus haute importance d'approfondir ces analogies afin de conclure sur le fait qu'à grande échelle, l’argile peut imiter la déformation du sel et que les concepts de tectonique salifère peuvent être appliqués à la tectonique argileuse. Les résultats de nos recherches soutiennent cette idée et encouragent une voie prometteuse pour l'avenir
Shale deforms under three major principles; (1) seismic scale plasticity (folding and faulting), (2) fluidization (mud volcanism), and (3) ductile strain/plasticity (distributed slow motion) and can mimic salt deformation under stress and strain. Ductility of these two rocks are governed by processes taking place beyond the ‘scale of observation’ (e.g. crystalline plasticity and pressure solution for salt; shear bands, folding and faulting for shale) forming a ‘distributed deformation’. Certain controlling factors such as confinement pressure, temperature, water content, rate of loading, and amount of sedimentation, modulate the ductile behavior of these rocks. When these controlling factors are met, ductile rocks (e.g. salt and shale) display behavioral similarity to viscous materials (e.g. fluids) in nature and their specific deformation-related signature (e.g. halokinesis, claykinesis) can be recorded within the sedimentary package surrounding these rock formations.However, the mobilization pattern of shales and hence the topic of Shale Tectonism is not yet as-well-identified-as salt due to the usual bad quality of acquired subsurface data (seismic) and the lack of well-preserved outcrop examples we are able to access around the world. Even though certain structures depicted as ‘diapirs’, ‘canopy features’, ‘minibasins’ and ‘welds’ have been recorded by the surrounding sedimentary cover in some natural cases and reported by researchers; unlike salt, no such conclusive remarks are made on the topic of shale mobility. In this PhD study, we worked on a well-imaged high-quality 3D seismic dataset and aimed to make a geometrical analysis of deformation in a shale-prone system (Ceduna Sub-Basin located in Great Bight Basin, Offshore Australia) in order to compare it with Salt Tectonics. The main purpose was to display the importance of mobilized shales on the structural development as well as proposing a kinematic scenario for the whole deltaic system (White Pointer Delta) driven above a thick shale detachment level (Blue Whale Formation). Following our research, we have come to realization that; - At large scale, shales display a plastic deformation pattern and behave like a fluid in a viscous manner mimicking salt deposits, while the deformation signature associated with shale mobilization can be recorded by the sediment strata surrounding these shale remnants (e.g. clay-kinesis). - From technical point of view, there are observed features with characteristics of salt tectonics such as wedges, welds and minibasins in the dataset. The gliding delta evolve from a classic deep water fold and thrust belt towards a thrust duplex, which suggests a change in shale rheology and strain hardening favoring a localization of deformation. - Locally, shales can be fluidized and form mud volcanoes in the studied Ceduna Sub-Basin area. Therefore, we propose that a duplexation mechanism initiates shale mobility above the early down-building structures in this region.It is of utmost importance to further investigate these analogies in order to conclude on the fact that at large scale; shale can mimic salt deformation and that the concept of Salt Tectonics can be applied to Shale Tectonics. First hand results of our research support this idea and encourage a promising path for the way forward

Clays and clay mineral distribution studies are important for understanding the geological history of the Gulf of Mexico Basin, but few studies document any subsurface clay mineral distribution in the Gulf of Mexico. Shale samples from nine wells (30 samples) in the South Timbalier protraction were selected near known paleontological markers identifying the Miocene, Pliocene, and Pleistocene boundaries. Bulk mineralogy of each sample, determined by XRD, is primarily mixed-layer smectite and illite with a minor amount of kaolinite. The mixed-layer mineralogies are end-member smectite, mixed-layer smectite, mixed-layer illite, and end-member illite. These clay mineral fractions do not correlate with age. The illite mixed layer percentage correlates with depth, but the correlation decreases when depth is converted to temperature. However, the illite mixed layer fraction does not exhibit a strong correlation in this multiwell study when compared to a single well study in Ship Shoal using identical methods (Totten et al., 2002).

Nous souhaitons connaître les processus qui contrôlent les glissements de terrain lents à l'aide de méthodes sismiques passives. Nous installons des dispositifs d'écoute sismique sur les sites de Super-Sauze (France) et de Valoria (Italie). Nous détectons, localisons et caractérisons trois types principaux de signaux sismiques. Un type est associé aux séismes régionaux donc externe à la dynamique des glissements. Les deux autres sont localisés dans des foyers de fissures ou des ruptures de pente. Nous suggérons que le premier type est associé à des écroulements depuis l'escarpement et à du transport en surface, tandis que le second type est associé à des fractures et des cisaillements. On montre qu'il existe des corrélations entre ces signaux, les déplacements en surface et les précipitations. Les glissements de terrain sont des volumes variables dans le temps et dans l'espace, ce qui impose une maintenance régulière des équipements et complexifie l'acquisition de données permanentes.

Les réservoirs pétroliers argileux sont caractérisés par des systèmes de pores associés à une distribution spatiale hétérogène à plusieurs échelles des phases minérales et organiques. Cette hétérogénéité nécessite une approche multi-échelle et multi-outils pour caractériser le réseau de pores. Une telle approche a été développée grâce à la sélection rigoureuse de 7 carottes issues de la formation de Vaca Muerta (Argentine), avec différentes maturations d'hydrocarbures mais des compositions minérales comparables. La tomographie RX 3D et la cartographie de la porosité par autoradiographie ont révélé les hétérogénéités à l'échelle des carottes, et permis d'identifier des zones homogènes pour le prélèvement de sous-échantillons comparables et représentatifs.Le couplage corrélatif de différentes techniques a permis d'atteindre un bilan quantitatif de la porosité / tailles de pores et pour la première fois, sur des blocs non broyées, notamment pour les expériences d'adsorption d'azote. Les résultats d’autoradiographie sont en accord avec les autres méthodes, indiquant que tous les pores sont connectés et accessibles par la résine d’imprégnation. Une diminution de la porosité totale ainsi que des tailles de pores a également été observée avec la maturation de la matière organique.Une approche innovante pour l'acquisition et le traitement de mosaïques d’images MEB a fourni des cartographies de la distribution des phases minérales et organiques à l'échelle du cm. Le couplage corrélatif avec la carte de porosité par autoradiographie des mêmes zones, a révélé les corrélations spatiales entre variations minéralogiques et de porosité
Gas shale reservoirs are characterized by pore systems, associated with a heterogeneous spatial distribution of mineral and organic phases at multiple scales. This high heterogeneity requires a multi-scale & multi-tool approach to characterize the pore network. Such an approach has been developed on 7 cores from the Vaca Muerta formation (Argentina), which belong to areas with various hydrocarbon maturities, but with comparable mineral compositions. 3D µtomography and quantitative 2D mapping of the connected porosity by autoradiography have been applied at the core scale, in aim to localize and analyze the spatial heterogeneities, and to identify similar homogenous areas for localizing comparable sub-samples.The correlative coupling of various techniques was applied to achieve quantitative balance of porosity and pore size distribution, from mm to nm scales on representative sub-samples and for the first time, on preserved blocks rather than crushed powders, even for nitrogen gas adsorption experiments. Results of autoradiography are in very good agreement with other total bulk porosities, indicating that all pores are connected and accessed by the 14C-MMA used for impregnation. Decreased total porosity and pore throat/body sizes were also observed as organic matter maturity increased. An innovative approach for electron microscopy images acquisition and treatment provided large mosaics, with the distribution of mineral and organic phases at the cm scale. The correlative coupling with the autoradiography porosity map of the same zone, revealed the spatial correlations between mineralogical variations and porosity

The Fayetteville Shale is composed dominantly of clay, carbonate, and siliciclastic minerals. A variety of facies have been described by other workers and in this study, defined by mineral content, biota, fabric, and texture. Because the Fayetteville Shale is one of the top shale-gas producing plays in the U.S., an inquiry into key drivers of good-quality production is worthwhile. In particular, a hypothesis that intervals of high clay content should be avoided as production targets is investigated in this study. A high level of separation between wire-line log neutron porosity (NPHI) and density porosity (DPHI) in the Fayetteville Shale is observed in contrast to the wire-line log responses from the Barnett and Haynesville Shales. Clay minerals have a significant effect on NPHI, which in turn affects separation between NPHI and DPHI (PHISEP). X-Ray Diffraction (XRD) clay data was available for three wells, and efforts to correlate XRD results to PHISEP led to establishing NPHI as a reasonable proxy for clay. Using NPHI as a proxy it was possible to pick clay-rich intervals, map them across the study area, and to determine net clay in the Fayetteville Shale. Maps of net clay-rich intervals were compared to a map of production, but revealed no obvious correlation. Stratigraphic cross-sections showing the clay-rich intervals revealed a clay-poor interval in the upper part of the lower Fayetteville. This interval is the primary target for horizontal well completion. It is bounded above and below by more clay-rich intervals. Establishing the clay-rich intervals via porosity log separation (PHISEP) is one tool to help determine possible stratigraphic zones of gas production and can lead to a better understanding of intervals in which to expect production.
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Slope instabilities have been affecting the grade slope of Provincial Trunk Highway 5 near the junction with Provincial Trunk Highway 10 in northwestern Manitoba for over 50 years. In recent years, the instabilities have resulted in significant damage to the highway pavement surface. In 2011, Manitoba Infrastructure and Transportation initiated a geotechnical investigation to gain a better understanding of the failure, identify possible failure mechanisms, and explore various remedial design alternatives in order to stabilize the slope. The site was instrumented with slope inclinometers and vibrating wire piezometers, and monitored over a period of two years. An extensive laboratory testing program was completed to compare the results of direct shear tests and torsional ring shear tests for determining the shear strength of the underlying Cretaceous clay shale. Measured values were compared with values back analyzed using limit equilibrium analysis. A coupled finite element model was used to model the expected excess porewater pressure response, and therefore the stability of the slope, during construction of a stabilization berm. It was subsequently calibrated to agree with the measured porewater pressure responses from the instrumentation. Finally, spring flood conditions were simulated to determine the effect of multiple flash flood events on the stability of the slope.

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Regional and within well variability in hydrocarbon production from organic carbon rich shales has demonstrated that these unconventional reservoirs are complex and require an in-depth understanding of geological factors to make successful predictions. Variability is apparent in porosity and permeability, mechanical properties governing fracture susceptibility for enhanced hydrocarbon release, and concentrations of organic carbon (OC). The economically successful, though variable Woodford Shale, Oklahoma, USA, shows a R2 = 0.72 correlation between mineral surface area (MSA) and total organic carbon (TOC) consistent with a mineral surface preservative effect on OC extending across a range of samples from multiple cores and with TOC values of <0.5% to 18%. The TOC and MSA data illustrates the systematic stratigraphic covariant relationship between TOC and MSA showing steps of up to 15% TOC that are matched by similar shifts in MSA. Transmission electron microscope (TEM) imaging performed on ~80 nanometre thick ultramicrotomed thin sections independently confirms quantitative geochemical clay-OC associations at the nanoscopic scale of interaction. Energy Dispersive Spectrometry (EDS) spot analyses reveal that organic carbon is entirely constrained to nanoscale clay laminae within the sample. Grey zones encapsulated by clay aggregates appear homogeneous at low magnifications and are similar to discrete organic matter particles commonly interpreted in recent studies. However, high resolution inspection resolves these zones in to laminated clay particles occurring at tens of nanometres. TEM micrographs of later stage submicron-scale quartz grain growth may also explain how the opposing mechanisms of hydrocarbon leaching and entrapment can co-exist for over 300 million years and provide an insight into shale brittleness, known to increase fracture susceptibility. Determining key modes of how OC is preserved during deposition and early diagenesis in proven gas-shales, such as the Woodford Shale encompasses a more holistic approach to enhancing the prediction of prospective hydrocarbon resources in frontier basins.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2012

To make bacterial-based self-healing concrete, alkaline-resistant bacterial spores, nutrient sources, and a calcium source are incorporated into a concrete matrix. Two ureolytic spore-forming bacteria, Sporosarcina pasteurii, Lysinibacillus sphaericus, and two non-ureolytic spore-forming bacteria, Bacillus cohnii, and Bacillus pseudofirmus, which have been used in previous studies as bacterial concrete healing agents, were compared in this study. The four bacteria were compared for their (1) sporulation rates on different sporulation agar plates, (2) growth in five liquid media, (3) survival rates in light weight aggregates (LWA) and in mortar samples, and (4) calcium carbonate precipitation rates from either calcium lactate or calcium nitrate. Sporulation was successfully induced after three-day incubation at 30°C on an appropriate sporulation medium. High sporulation rates of B. cohnii, and B. pseudofirmus(93% and 99% respectively) were found on alkaline R2A medium (AR2A). A sporulation rate (89%) of S. pasteruiiwas observed on tryptic soy agar supplemented with 2% urea (TSAU).The highest sporulation rate (60%) of L. sphaericuswas found on R2A medium supplemented with 2% urea (R2AU). In the growth study, tryptic soy broth supplemented with 2% urea (TSBU) was a positive control which supported rapid growth of all four bacteria. Sporosarcina pasteurii and L. pasteuriishowed rapid growth rates in alkaline yeast extract broth (AYE) and yeast extract with 2% urea broth (YEU) respectively. In contrast, B. cohnii, and B. pseudofirmusgrew poorly in all media except in the positive control. Viable counts of the four bacterial spores reduced (1.8–3.3 logs) during the first 24 h in mortar samples and then remained stable for next 27 days testing period. Among the four, S. pasteuriishowed the smallest reduction of viable counts (1.8–2.5 logs) in mortar after one day of incubation. Both S. pasteuriiand L. sphaericusshowed high CaCO₃ productions (>80%) after 24 h incubation at 30°C in YEU containing either calcium nitrate or calcium lactate. However, B. pseudofirmusand B. cohnii showedlow calcite recovery rates (<11%) in AYE containing eithercalcium nitrate or calcium lactate under the same incubation condition. Overall, S. pasteuriiwas the best bacterial concrete healing agent of the four. This bacterium had (1) rapid growth rate in AYE, (2) about 90% sporulation rate within 3 days, (3) highest survival rates after 24 h in mortar samples and, (4) high CaCO₃ precipitation rates, 82 or 98%, in broth containing calcium nitrate or calcium lactate respectively.

In addition, two different lightweight aggregates (LWA), expanded shale (ES) and expanded clay (EC), which were used as bacterial carriers and protective materials, were compared in this study. Each type of LWA was separated into three sizes (<0.85 mm, 0.85– 2.0 mm, and >2.0 mm) and immobilized with spores of B. cohniior B. pseudofirmus.Viable counts recovered from EC and ES reduced <1.0 log after the immobilization process and remained stable during the 150 days testing period. Neither the type nor the particle sizes of the two LWA significantly affected the survival rates of the bacterial spores. This result showed that both EC and ES could be used as carriers for bacterial healing agents. It was also found that when the spores were immobilized with nutrients in LWA, their survival rates in mortar samples can be improved slightly (<1.0 log).

This research takes a multidisciplinary approach to comprehensively investigate the material and mechanical properties as well as pore water chemistry of the Bearpaw shale. This made it possible to characterize how these properties relate to the mechanical strength of this material. The results of this research challenge our ideas of the hydrogeology and of the geological history of the region. Core samples of the Bearpaw Formation and the overlying glacial till were collected from a field site in southern Saskatchewan, Canada. A combination of laboratory tests including multi-staged oedometer tests, constant rate of strain oedometer tests, specialized triaxial swell tests, along with pore water chemistry and finite element modelling were used to meet the following objectives: (1) To investigate the material properties and compression behaviour of the Bearpaw in addition to assessing disturbance due to specimen size; (2) Examine the time dependent behaviour of the Bearpaw and the transferability of time rate models developed for soft soils to stiff soils; (3) Examine the swelling potential and behaviour of the Bearpaw Formation and the influence of boundary conditions on this behaviour, while assessing the applicability of the swell concepts developed for compacted materials to a naturally swelling clay material; and (4) Constrain the depositional age of the till overlying the Bearpaw Shale. Contrary to what is seen in soft soils, smaller sized specimens were found to reduce disturbance, and produce more accurate and consistent results. Creep was found to follow the same laws as it does in soft soils, calling into question whether the use of preconsolidation pressure to predict geological history in stiff clays is appropriate. There was significant variation in the observed swell pressures of samples of the same size and depth. Finally, the glacial till at site was found to belong uniquely to the Battleford Formation and ranges in age from 22,500 to 27,500 years which is much younger (over 100,000 years younger) than previously believed.
Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2010-01-29 01:34:14.071

Magister Scientiae - MSc
Pressure drop within a field can be attributed to several factors. Pressure drop occurs when fractional forces cause resistance to flowing fluid through a porous medium. In this thesis, the sciences of petrophysics and rock physics were employed to develop understanding of the physical processes that occurs in reservoirs. This study focussed on the physical properties of rock and fluid in order to provide understanding of the system and the mechanism controlling its behaviour. The change in production capacity of wells E-M 1, 2, 3, 4&5 prompted further research to find out why the there will be pressure drop from the suits of wells and which well was contributing to the drop in production pressure. The E-M wells are located in the Bredasdorp Basin and the reservoirs have trapping mechanisms of stratigraphical and structural systems in a moderate to good quality turbidite channel sandstone. The basin is predominantly an elongated north-west and south-east inherited channel from the synrift sub basin and was open to relatively free marine circulation. By the southwest the basin is enclose by southern Outeniqua basin and the Indian oceans. Sedimentation into the Bredasdorp basin thus occurred predominantly down the axis of the basin with main input direction from the west. Five wells were studied E-M1, E-M2, E-M3, E-M4, and E-M5 to identify which well is susceptible to flow within this group. Setting criteria for discriminator the result generated four well as meeting the criteria except for E-M1. The failure of E-M1 reservoir well interval was in consonant with result showed by evaluation from the log, pressure and rock physics analyses for E-M1.iv Various methods in rock physics were used to identify sediments and their conditions and by applying inverse modelling (elastic impedance) the interval properties were better reflected. Also elastic impedance proved to be an economical and quicker method in describing the lithology and depositional environment in the absence of seismic trace.

The Blanka tunnel has two boring sections: Brusnice tunnel and Královská obora tunnel. Both tunnels were boring in difficult geologycal conditions, but the geology conditions of these tunnels are not same. Also they had not the same hazards during boring. There was used a spectrum of different technical works with hazard reduction purpose and safety process of boring. There were three serious accidents, wnich everyone made a creater on the surface, but they have not the same causes. This text has a task to describe a geological survey before and during the boring of both tunnels. How other reasons affected the process of boring? How the tunnels were bored? What events preceded the everyone of three major failure? This text does not deal with economical things of boring and effects of specific personal influence on the process of boring. Key words Tunnel, excavation, Blanka, Brusnice, Letná, Stromovka park, Vltava river, underground water, geology, ordovik, New Austrian Tunnelling method, pilot tunnel, calotte, bench, bottom, arche, bolt, lining, grouting, collapse of ceiling, failure, tube, shale, quarzite, soil, loess, ballast, clay