Outcrop analog studies have long been used to define subsurface correlation strategies and improve predictions of reservoir heterogeneities that can complicate production behavior. Recent advancements in geographic information software, 3D geologic modeling techniques, and survey equipment have the potential to revolutionize outcrop analog studies. A workflow is developed to create digital outcrop models using a reflectorless total station, a digital camera, Erdas Photogrammetry Module™, and Gocad™ to document complex stratal variations across kilometers-long outcrops. Combining outcrop digital elevation models with orthorectified photographs and detailed sedimentologic logs provides a framework for static 3D reservoir analog models. Developed methodologies are demonstrated by mapping rock variations and stratal geometries within several kilometers-long, sub-parallel exposures of the Lower Sego Sandstone in San Arroyo Canyon, Book Cliffs, Utah. The digital outcrop model of the Lower Sego Sandstone documents complex bedding geometry and facies distribution within two sharp-based sandstone layers. A mapping of allostratigraphic surfaces through the digital outcrop model provided a framework in which to analyze facies variations. These surfaces included: 1) Basal erosion surfaces of these layers interpreted to have formed by tidal erosion of the sea floor during shoreline regression; 2) a high relief erosion surface within the upper layer interpreted to have formed during lowstand fluvial incision; and 3) top contacts of layers defined by abrupt fining to marine shale, which are interpreted to record marine ravinement during transgression. Facies variations within the lower layer include low sinuosity distributary channel deposits incised into highly marine bioturbated sandstone. Deposits above the high-relief erosion surface within the upper layer are a classic valley fill succession, which processes upward from lowstand fluvial channel deposits, to heterolithic estuarine deposits, and finally to sandy landward-dipping beds of an estuarine mouth shoal deposit. The digital outcrop model allows surfaces and facies observation to be mapped within a structured 3D coordinate system to define reservoir analog models.

Outcrop analog studies have long been used to define subsurface correlation strategies and improve predictions of reservoir heterogeneities that can complicate production behavior. Recent advancements in geographic information software, 3D geologic modeling techniques, and survey equipment have the potential to revolutionize outcrop analog studies. A workflow is developed to create digital outcrop models using a reflectorless total station, a digital camera, Erdas Photogrammetry Module™, and Gocad™ to document complex stratal variations across kilometers-long outcrops. Combining outcrop digital elevation models with orthorectified photographs and detailed sedimentologic logs provides a framework for static 3D reservoir analog models. Developed methodologies are demonstrated by mapping rock variations and stratal geometries within several kilometers-long, sub-parallel exposures of the Lower Sego Sandstone in San Arroyo Canyon, Book Cliffs, Utah. The digital outcrop model of the Lower Sego Sandstone documents complex bedding geometry and facies distribution within two sharp-based sandstone layers. A mapping of allostratigraphic surfaces through the digital outcrop model provided a framework in which to analyze facies variations. These surfaces included: 1) Basal erosion surfaces of these layers interpreted to have formed by tidal erosion of the sea floor during shoreline regression; 2) a high relief erosion surface within the upper layer interpreted to have formed during lowstand fluvial incision; and 3) top contacts of layers defined by abrupt fining to marine shale, which are interpreted to record marine ravinement during transgression. Facies variations within the lower layer include low sinuosity distributary channel deposits incised into highly marine bioturbated sandstone. Deposits above the high-relief erosion surface within the upper layer are a classic valley fill succession, which processes upward from lowstand fluvial channel deposits, to heterolithic estuarine deposits, and finally to sandy landward-dipping beds of an estuarine mouth shoal deposit. The digital outcrop model allows surfaces and facies observation to be mapped within a structured 3D coordinate system to define reservoir analog models.

The Torlesse composite terrane is an important geological unit in Canterbury, New Zealand, making up the backbone of the Southern Alps. It consists of a large group of rock that exhibits a range of engineering geological conditions. This study has been undertaken to characterise the range in engineering geological conditions throughout the Torlesse of Canterbury in order to develop a rock mass classification scheme specific to this abundant and complex rock type. The classification is aimed to aid in TBM tunnelling assessment in the Torlesse, which enables sub-division of an area or tunnel alignment into rock mass domains. Furthermore the classification enables the prediction of rock masses through geological controls in areas of poor outcrop coverage. Four sites throughout Canterbury were selected for mapping to represent Torlesse terrane types, metamorphic facies and a range of regional fault settings: the Elliott Fault, Hurunui River, Ashley River Gorge and Opuha Dam. A preliminary desktop study was carried out with a landscape lineation analysis to develop 1) a conceptual geological model at each study site and 2) field mapping sheets to provide a check list to ensure consistency of information collected between outcrops and sites. Lineations and conceptual models identified a series of structural blocks within sites, which were further validated by field mapping. Outcrop field mapping was carried out across selected extents of study sites using the field sheets from the desktop study. Using NZGS (2005) and ISRM (1978) derived parameters, rock mass characteristics, including lithology and defect information, were recorded on the field sheets. A laboratory testing programme on selected outcrop intact rock was undertaken to support field work and later classification development. Data from field work was plotted to derive rock mass trends. Trends were used to develop a classification framework. It was found the rock mass could be defined by bedding thickness, degree of fracture and the combination of discontinuities such as persistent jointing and shearing, which defined dominant rock mass control. The rock mass could therefore be classified based on: blockiness, defined by bedding thickness and density of non-systematic jointing (fractures); and defect structure, defined by the combination of systematic discontinuities such as persistent jointing and shearing. The two principle rock mass governing controls were related together on an XY plot to form the conceptual Torlesse rock mass classification (TRC). Six classes encompassing the range of conditions observed in the Torlesse were devised for blockiness and defect structure. Blockiness classes range from: thickly bedded to massive sandstone with slight to moderate fracture, to very thin to thin bedded sandstone that is fragmented. Defect structure classes range from rock masses defined by: dominant systematic, persistent jointing with rare faulting, to rock masses typical of major shear zones, where material geotechnically behaves as a soil with no principle defect sets. Individual outcrop plotting then allowed rock masses typical of each site to be grouped on the TRC. Clusters of each study sites’ outcrops were overlaid to characterise all rock mass types observed throughout this research. This allowed representative identification of eight distinctive rock mass types (Types 1-8) that are indicative of the Torlesse composite terrane of Canterbury. Each type has a series of geological controls that influence the nature of the rock mass. Geological controls can aid in the prediction of rock mass conditions for tunnel alignment selection. Lithostructure and proximity to major structures were defined as major rock mass type controls. Lithostructure defines the effect of lithology on bedding thickness and fracturing by non-systematic jointing. Medium to massive bedding as part of rock mass Types 1 and 2 result in the best rock mass. In the sandstone-rich rock mass, systematic jointing dominates with less shearing and faulting and a lower occurrence of short, discrete, non-systematic jointing. Conversely, the thinly bedded Torlesse represented by rock mass Type 5 lacks persistent jointing. This type, being mudstone dominant, fractures more easily, is characterised by short, discrete jointing, and tends to localise faulting, shearing and some folding. Modern tectonic stress fields are also a major control. The size of the tectonic structure can impact different volumes of rock. Rock outside the direct fault zone can also be impacted giving rise to rock mass Type 6. For example, increased levels of shearing are observed in adjacent rock at both the Elliott and Opuha Dam Faults. Rock mass Types 7 and 8 represent the rock masses directly affected by large tectonic structures. Sub-dividing proposed tunnel alignments by rock mass type allows assessment of tunnelling parameters. Dependant on project specific rock mass types expected, different TBM design will be suited. This has significant implications on support measures. Open gripper TBM’s are likely to be suited to rock mass Types 1 and 2. This rock mass is expected to represent the best rock mass stability but will be the hardest to excavate. As a result, rock bolt, mesh and shotcrete will likely prevent significant block failure through gravity release. Rock mass Types 3 and 4 are expected to represent a favourably interlocked rock mass, resulting in increased penetration rate but whose advance rate is likely to be hindered by the need for more extensive support. As rock mass Types 5-8 increase in abundance, shielded TBM’s will likely be best suited due to questionable thrust generation and support requirements toward the poorer rock masses. Penetration rates will be high but advance rates are expected to be low. Significant potential for failure exists in the poorer rock mass types without adequate support, including running ground. The selection of a shielded or gripper TBM will depend on the proportion and lengths of each TRC rock mass type anticipated along a tunnel alignment. The opportunity exists for future work to refine and validate the TRC classification through increased data input, more extensive laboratory testing and its application to tunnelling projects. Furthermore it is hoped the TRC can be used for other types of geotechnical applications, at a variety of scales where Torlesse is concerned. To do this the TRC interpretations with respect to rock mass behaviour must be adapted to different scales.

Diversos estudos florísticos vem sendo realizados nos campos rupestres; entretanto, a vegetação dos afloramentos rochosos é pouco estudada, pois a maior parte das pesquisas tem focado áreas campestres. Nessa perspectiva, um estudo florístico foi realizado em sete afloramentos rochosos na Serra do Cipó, no estado de Minas Gerais. Com base em uma imagem de satélite, foi traçada uma parcela de 500 x 500 m, e os afloramentos rochosos contidos nessa parcela foram selecionados como áreas de estudo. Tais afloramentos estão divididos em quatro pontos, distando 5 km entre si pela rodovia MG 010; um desses pontos, formado por dois afloramentos, situa-se no interior do Parque Nacional da Serra do Cipó. Todas as plantas com flores que ocorriam nessas áreas foram coletadas, e um total de 55 famílias e 307 espécies foram identificadas. As análises de similaridade da composição florística indicaram uma maior similaridade em afloramentos em um mesmo ponto. O solo dos afloramentos estudados apresentou as mesmas características de solos de outros afloramentos rochosos já documentados na literatura. Comparações entre os dados obtidos no presente estudo e da Flora brasileira ameaçada de extinção e da Lista Vermelha das Espécies Ameaçadas de Extinção da Flora de Minas Gerais evidenciaram 56 espécies diferentemente listadas como ameaçadas. Além disso, 22 espécies encontradas nos afloramentos rochosos estudados foram identificadas como espécies raras. Por fim, novas contribuições também foram feitas para a Flora Vascular do Cerrado e a Flora da Serra do Cipó, pois foram reveladas espécies ausentes nesses trabalhos. Esses resultados podem ter sido causados por problemas de sub-amostragem, especialmente das espécies herbáceo-subarbustivas, uma vez que estudos da estudos da flora herbáceo-arbustiva são mais propensos a enviesamentos causados por esse tipo de problema. Áreas de campos rupestres são caracterizadas por diversos microhabitats, entretanto, faltam estudos voltados para suas delimitações. Com base nos resultados de análises multivariadas empregando dois métodos (UPGMA e DCA), esse estudo analisou as relações de similaridade florística entre os afloramentos rochosos estudados na Serra do Cipó e 23 áreas de Cerrado (sensu lato e sensu stricto), e também entre aqueles e outras 35 localidades com afloramentos rochosos. As análises incluíram todos os componentes da vegetação. Os resultados variam de acordo com a análise e com os dados utilizados, mas evidenciam a necessidade de delimitação dos habitats para embasar uma comparação mais refinada entre diferentes localidades. / Several floristic studies have been carried out on campos rupestres on the past years; however, the rock outcrop vegetation is still understudied, for most of the surveys have mainly focused on grassland areas. In this perspective, a floristic study was carried out on seven rock outcrops on Serra do Cipó, in Minas Gerais state. Based on a satellite image, a parcel with 500 x 500 m was assembled, and the rock outcrops within this parcel were selected as study areas. These outcrops are divided into four subareas, which are five kilometers apart from each other, along the MG 010 road; one of these subareas, containing two outcrops, was located within the boundaries of Parque Nacional da Serra do Cipó. All flowering plants occurring on the rock outcrops were collected, and a total of 55 families and 307 species were identified. The floristic composition similarity analyses indicated a higher similarity between rock outcrops within the same subarea. Soil from the studied areas presented the same characteristics documented by studies carried out on other rock outcrops. Comparisons between data from the present study and from Flora brasileira ameaçada de extinção e da Lista Vermelha das Espécies Ameaçadas de Extinção da Flora de Minas Gerais showed that 56 species are differently listed under threatened categories. Also, 22 species occurring on the studied rock outcrops were identified as rare species. Furthermore, the present floristic study contributed to Flora Vascular do Cerrado and to Flora da Serra do Cipó, given that some species were absent in these treatments. These results might have been caused by sub-sampling problems, especially of herbaceous and subshrubby species, as studies with herbaceous and subshrubby flora are more likely to be biased by this kind of problem. Campos rupestres areas are characterized by several microhabitats; however, studies focusing on their delimitation are lacking. Based on the results of multivariate analyses using two methods (UPGMA and DCA), this study analyzed the relationships of floristic similarity between the rock outcrops studied in Serra do Cipó and 23 Cerrado areas (sensu lato e sensu stricto), and also between those and another 35 localities with rock outcrops. The analyses included all components of vegetation. Results varied according to the method and data employed, yet they strengthen the need of delimiting the habitats to allow a more precise comparison between different localities.

Diversos estudos florísticos vem sendo realizados nos campos rupestres; entretanto, a vegetação dos afloramentos rochosos é pouco estudada, pois a maior parte das pesquisas tem focado áreas campestres. Nessa perspectiva, um estudo florístico foi realizado em sete afloramentos rochosos na Serra do Cipó, no estado de Minas Gerais. Com base em uma imagem de satélite, foi traçada uma parcela de 500 x 500 m, e os afloramentos rochosos contidos nessa parcela foram selecionados como áreas de estudo. Tais afloramentos estão divididos em quatro pontos, distando 5 km entre si pela rodovia MG 010; um desses pontos, formado por dois afloramentos, situa-se no interior do Parque Nacional da Serra do Cipó. Todas as plantas com flores que ocorriam nessas áreas foram coletadas, e um total de 55 famílias e 307 espécies foram identificadas. As análises de similaridade da composição florística indicaram uma maior similaridade em afloramentos em um mesmo ponto. O solo dos afloramentos estudados apresentou as mesmas características de solos de outros afloramentos rochosos já documentados na literatura. Comparações entre os dados obtidos no presente estudo e da Flora brasileira ameaçada de extinção e da Lista Vermelha das Espécies Ameaçadas de Extinção da Flora de Minas Gerais evidenciaram 56 espécies diferentemente listadas como ameaçadas. Além disso, 22 espécies encontradas nos afloramentos rochosos estudados foram identificadas como espécies raras. Por fim, novas contribuições também foram feitas para a Flora Vascular do Cerrado e a Flora da Serra do Cipó, pois foram reveladas espécies ausentes nesses trabalhos. Esses resultados podem ter sido causados por problemas de sub-amostragem, especialmente das espécies herbáceo-subarbustivas, uma vez que estudos da estudos da flora herbáceo-arbustiva são mais propensos a enviesamentos causados por esse tipo de problema. Áreas de campos rupestres são caracterizadas por diversos microhabitats, entretanto, faltam estudos voltados para suas delimitações. Com base nos resultados de análises multivariadas empregando dois métodos (UPGMA e DCA), esse estudo analisou as relações de similaridade florística entre os afloramentos rochosos estudados na Serra do Cipó e 23 áreas de Cerrado (sensu lato e sensu stricto), e também entre aqueles e outras 35 localidades com afloramentos rochosos. As análises incluíram todos os componentes da vegetação. Os resultados variam de acordo com a análise e com os dados utilizados, mas evidenciam a necessidade de delimitação dos habitats para embasar uma comparação mais refinada entre diferentes localidades. / Several floristic studies have been carried out on campos rupestres on the past years; however, the rock outcrop vegetation is still understudied, for most of the surveys have mainly focused on grassland areas. In this perspective, a floristic study was carried out on seven rock outcrops on Serra do Cipó, in Minas Gerais state. Based on a satellite image, a parcel with 500 x 500 m was assembled, and the rock outcrops within this parcel were selected as study areas. These outcrops are divided into four subareas, which are five kilometers apart from each other, along the MG 010 road; one of these subareas, containing two outcrops, was located within the boundaries of Parque Nacional da Serra do Cipó. All flowering plants occurring on the rock outcrops were collected, and a total of 55 families and 307 species were identified. The floristic composition similarity analyses indicated a higher similarity between rock outcrops within the same subarea. Soil from the studied areas presented the same characteristics documented by studies carried out on other rock outcrops. Comparisons between data from the present study and from Flora brasileira ameaçada de extinção e da Lista Vermelha das Espécies Ameaçadas de Extinção da Flora de Minas Gerais showed that 56 species are differently listed under threatened categories. Also, 22 species occurring on the studied rock outcrops were identified as rare species. Furthermore, the present floristic study contributed to Flora Vascular do Cerrado and to Flora da Serra do Cipó, given that some species were absent in these treatments. These results might have been caused by sub-sampling problems, especially of herbaceous and subshrubby species, as studies with herbaceous and subshrubby flora are more likely to be biased by this kind of problem. Campos rupestres areas are characterized by several microhabitats; however, studies focusing on their delimitation are lacking. Based on the results of multivariate analyses using two methods (UPGMA and DCA), this study analyzed the relationships of floristic similarity between the rock outcrops studied in Serra do Cipó and 23 Cerrado areas (sensu lato e sensu stricto), and also between those and another 35 localities with rock outcrops. The analyses included all components of vegetation. Results varied according to the method and data employed, yet they strengthen the need of delimiting the habitats to allow a more precise comparison between different localities.

This research characterizes the nature of fractures in Paleozoic and Mesozoic caprock seal analogs exposed in central and south-eastern Utah. The results of this research show evidence for fluid flow and mineralization in the subsurface as well as reactivation of fractures suggesting that the fractures act as a loci for fluid flow through time. The heterolithic nature of the caprock seals and meso-scale (cm to m) variability in fracture distributions and morphology highlight the strong link between the variation in material properties and the response to changing stress conditions. The variable connectivity of fractures and the changes in fracture density at the meso-scale plays a critical role in subsurface fluid flow. The presence or formation of new fractures can result in seal bypass systems, which can cause failure of hydrocarbon traps, CO2 geosequestration sites, waste and subsurface fluid repositories. An integrated approach of field, borehole geophysical, burial and stress history modeling, rock strength testing, and numerical modeling are used to understand the effects changing material properties, rock strength, and stress history have on sealing capacity. Simplified stress history models derived from burial history curves are combined with laboratory derived rock properties to understand the importance variations in rock properties and differential and effective mean stress have on the mechanical failure of fine-grained clastic sedimentary rocks. Burial history and rock strength data show that in units that experience similar burial depths and changing mechanical property exert a control on deformation type. Geomechanical models reveal changes in local strain magnitudes at locked mechanical interfaces, suggesting that elastic mismatch between layers results in differential strain distribution. Characterization of fracture patterns, rock strength variability and the modeled changes in subsurface strain distribution is especially important for understanding the response of low-­‐permeability rocks to changing stress in the subsurface, and is applicable to multiple geo-engineering scenarios such as exploitation of natural resources, waste disposal, and management of fluids in the subsurface. The analyses presented in this dissertation provide analog fracture data for fine-grained clastic rocks and a dataset for better understanding the importance of heterogeneity in low permeability rocks.

Sub-surface reservoirs are normally characterised by limited information from widely spaced wells (1D sections) and relative low-resolution seismic data (2D or 3D sections) making any derived geological model highly interpretive. The ability of outcrop exposures to study the sedimentary architecture (e.g. stacking patterns, lateral continuation, facies proportions and distribution) at a wide range of scales (km to mm) in continuous 3D accessible sections make them ideal analogues to help bridge the gap in resolution between seismic and well data in reservoir studies.In this study the sedimentary architecture of the outcrop exposures the Late Triassic Wolfville Formation are evaluated using traditional sedimentological (e.g. correlation panels, log sections) and digital (e.g. DGPS, LiDAR, DEM) field techniques to help better understand these often complex fluvial depositional systems for analogue reservoir studies. The sediments of the Wolfville Formation are superbly exposed in both cliff sections and on extensive wave-cut platforms along the shore of the Minas Basin (Nova Scotia, Canada). The succession lies unconformably on Pre-Triassic rocks and forms the earliest syn-rift unit in the Fundy basin. The unit comprises coarse- and fine-grained fluvial sandstones, aeolian dune deposits, and alluvial fan sediments. The laterally extensive and three-dimensional nature of the outcrop exposures offer a valuable insight in the sedimentary architecture of the fluvial system. A detailed sedimentological analysis of the succession allowed the determination of the large-scale sedimentary architecture of this gravelly to sandy bedload fluvial system. In order to characterise the architectural evolution in more detail digital outcrop studies were employed in three carefully selected study areas. The study areas are located along the southern Minas Basin shore within the gravelly and younger sandy-dominated part of the succession.The digital outcrop studies carried out in the study areas collected spatial data using differential GPS and LiDAR (Light Detection and Ranging) equipment. The integration of traditional collected geological and spatial data forms digital outcrop models (DOMs), which allow accurate mapping and evaluation of the geological properties geometry and distribution using novel spatial analysis techniques (e.g. classified point-cloud and perpendicular projection plane method). The results offer a better understanding on the heterogeneity of the depositional system, accurate geostatistical information on the characteristics of sedimentary bodies and genetic units (geometry, distribution and proportion) and provides a high-resolution stratigraphic-structural framework for geocellular outcrop models. In the geocellular outcrop models of the study areas the three-dimensional facies distribution are simulated using various modelling approaches, such as sequential indicator simulations, object modelling and multiple point statistics. The available control of the outcrop models allowed the various facies modelling approaches to be examined. The results are evaluated and discussed using qualitative comparison studies. In addition, these outcrop models provided detailed information on the three-dimensional fluvial architecture.

Fractures can increase the permeability and producability of reservoirs by acting as fluid and gas conduits to wells. Networks of fractures are most important in reservoirs where little to no matrix permeability exists such as tight gas sandstones. Two significant variables, fracture length and the abundance of fractures, are not readily measurable from subsurface observations such as those obtained from cores or well logs. Numerical models suggest natural fracture apertures and lengths follow systematic power-law (Marrett, 1996; Olson, 2007) and negative exponential distributions (Olson, 2004); fracture trace lengths are interrogated. This study tests those propositions through study of fractures in outcrop. Outcrops of the Cretaceous Frontier Formation at Oyster Ridge in southwest Wyoming and Oil Mountain near Casper, in central Wyoming provide evidence of reservoir scale fracture networks in sandstones. In the subsurface the Frontier Formation sandstones are reservoirs that produce gas and oil in several Wyoming basins. I mapped fracture patterns at twenty locations at Oyster Ridge and Oil Mountain and measured fracture trace length distributions and abundance (intensity). Fracture cumulative length distribution plots illustrate systematic length distributions. Trace length distributions of every fracture network follow negative exponential distributions regardless of the number of fractures (N = 39 to N = 394) or the size of the outcrop (1.3 to 710 m²). Results show that the fractures follow a negative exponential distribution over a range of lengths of a few centimeters to tens of meters. These trace length distributions are consistent with geomechanical model fracture pattern simulation results by Olson (2004) that suggests negative exponential trace length distribution result from fracture to fracture interaction during fracture formation. Length distributions from my field study are inconsistent with pattern simulation results by Marrett (1996) and Olson (2007) and others that produce power-law length distributions. This inconsistency suggests that the model assumptions of Olson (2004) best account for the patterns I observed. Two dimensional fracture intensity, defined as the total fracture trace length divided by the map area, was measured for each outcrop to determine how structural position affects fracture abundance patterns. Two-dimensional fracture intensity measurements collected at thirteen structural locations around Oil Mountain show higher values of fracture intensity near the fold-axial-trace compared to fold limbs. The difference is as much as 7.4 fractures per meter near fold hinges compared to 0.63 fractures per meter in fold limbs. Outcrops near small faults, with displacement of a few meters, show an increase in fracture intensity from background values around 4.8 fractures per meter to values nearly three times as high (13 fractures per meter) near faults. Values of fracture intensity that are more elevated near small tear faults imply that faulting has a greater influence on fracture intensity than folding. / text

Ooid grainstone reservoir architecture remains poorly understood, particularly because of sedimentologic and stratigraphic heterogeneities that are innate to grainstone body development. Understanding of Geospatial relationships and recovery of hydrocarbons from these significant reservoir facies can be improved with access to outcrop analog information from well exposed examples. Object-based models and other modern subsurface reservoir models are considered superior methods for portraying realistic sediment distributions. These models, however, are highly dependent on input data describing sediment-body geometry for faithful template generation. Such input data are notably rare in carbonate systems. Maps generated from modern depositional patterns give a first approximation of areal distribution, but they are not as useful for understanding final preserved stratigraphic thickness and internal facies, sedimentary structure, and grain-type patterns. For this purpose, studies of exceptional outcrops are required. The 18 km long oblique-dip-oriented wall of the Shattuck Escarpment provides such a unique exposure of Permian-age grainstones. The Shattuck Escarpment in the Guadalupe Mountains provides an oblique-dip profile that exposes a near-complete middle Permian Grayburg mixed clastic-carbonate shelf succession of three high-frequency sequences which contain 30 high-frequency cycles. Particularly important for this study are the four cycles that display full updip to downdip extents of ooid grainstone tidal bar and tidal delta objects. The data from the Shattuck wall presented in this paper focusses on the transgressive portion of the upper Grayburg, or G12 high-frequency sequence (HFS), located 5 km landward of the time-equivalent shelf margin. This interval is an analog for productive fields along the northwest shelf of the Delaware Basin and on the eastern flank of the Central Basin Platform. The goal of this project is to understand the sedimentology and facies/cycle architectural variability of tidally influenced shelf crest ooid grainstones of the Grayburg Formation. Comparing this outcrop data to modern grainstone deposits allows the reader to understand the small-scale and large-scale sedimentologic and architectural patterns in analogous subsurface ooid grainstone reservoirs. Spatial analysis of these cycles was carried out using measured sections and GigaPan (high resolution photomosaic) data. Petrophysical (Porosity and Permeability) data was collected from three separate vertical core plug transects approximately 1 km apart with a vertical resolution of 30 cm. Cycle-set-scale grainstone complexes up to 6m thick extend at least 4.25 km along depositional dip and show variations in permeability between 6-400 mD and porosities between 8-20% within the lower portions of the grainstone complex. / text

Schichtung und Störungszonen sind typische Phänomene in Sedimentbecken wie dem Nordwestdeutschen Becken. Diese Gesteinsheterogenitäten können großen Einfluss auf viele verschiedene Fragestellungen im Zusammenhang mit der Exploration, dem Bohren und der hydraulischen Stimulation des geothermischen Reservoirs haben. Diese Doktorarbeit liefert Aussagen und Ansätze, wie hoch aufgelöste Daten, die in Aufschlüssen erhoben wurden, für eine verbesserte Vorhersage des Störungszonenaufbaus und der gesteinsmechanischen Eigenschaften in größeren Tiefen verwendet werden können. Um den Aufbau von Störungszonen und assoziierten Bruchsystemen in Sedimentgesteinen besser zu verstehen, wurden 58 Abschiebungen im Aufschlussmaßstab detailliert analysiert. Der Schwerpunkt lag dabei auf der Analyse von Bruchorientierung, -dichte, -öffnungsweite und -länge – jeweils getrennt betrachtet für Bruchzone und Nebengestein – sowie auf den strukturellen Indizes. Es konnten deutliche Unterschiede zwischen karbonatischen und klastischen Gesteinen festgestellt werden: in karbonatischen Gesteinen treten häufig ausgeprägte Bruchzonen mit erhöhten Bruchdichten auf. Während die maximale Öffnungsweite für beide Einheiten ähnlich ist, ist der Anteil an Brüchen mit großen Öffnungsweiten in der Bruchzone deutlich größer als im Nebengestein. In Karbonatgesteinen kann die Bruchorientierung in der Bruchzone stark von der im Nebengestein abweichen. In klastischen Gesteinen dagegen sind in beiden Einheiten ähnliche Bruchorientierungen zu finden. Die Auswertung der strukturellen Indizes zeigt, dass Abschiebungen in Karbonatgesteinen eher bruchzonen-dominiert sind als solche in klastischen Gesteinen und folglich größeren positiven Einfluss auf die Reservoirpermeabilität haben. Auf Basis der bestimmten Bruchdichtenverteilungen und Elastizitätsmoduli wurden effektive Steifigkeiten Ee innerhalb der Abschiebungen berechnet. Dabei zeigen Bruchzonen in klastischen Gesteinen eine deutlich geringere Abnahme der Steifigkeiten als solche in Karbonatgesteinen. Um die Kenntnisse über Eigenschaften typischer Gesteine im Nordwestdeutschen Becken zu erweitern, wurden physikalische (Vp-Geschwindigkeit, Porosität, Rohdichte und Korndichte) und gesteinsmechanische Parameter (Einaxiale Druckfestigkeit [UCS], Elastizitätsmodul, Zerstörungsarbeit und Zugfestigkeit; jeweils parallel und senkrecht zur sedimentären Schichtung) an 35 Gesteinsproben aus Aufschlüssen und 14 Bohrkernproben bestimmt. Für einen Teil dieser Proben (eine Vulkanit- sowie jeweils drei Sandstein- und Kalksteinproben) wurden Triaxialmessungen durchgeführt. Da Bohrkernmaterial selten ist, war es Ziel dieser Arbeit, die in-situ-Gesteinseigenschaften anhand von Aufschlussproben vorherzusagen. Die Eigenschaften von Proben aus größeren Tiefen werden dann mit denen äquivalenter Proben verglichen, d.h. Bohrkern und äquivalente Aufschlussprobe haben das gleiche stratigraphische Alter und eine vergleichbare sedimentäre Fazies. Die Äquivalenz der Proben wurde anhand von Dünnschliffen sichergestellt. Empirische Beziehungen bzw. Korrelationen zwischen UCS und allen physikalischen und geomechanischen Parametern wurden mit Regressionsanalysen bestimmt, jeweils lithologisch getrennt für alle Proben (inkl. Bohrkerne) und nur für Aufschlussproben. Die meisten Korrelationen haben ein hohes Bestimmtheitsmaß; die Ergebnisse der Bohrkerne liegen meist innerhalb der 90% Prognosebänder der Korrelationen, die für Aufschlussproben berechnet wurden. Auf ähnliche Weise wurden anhand von mehreren Triaxialmessungen pro Probe linearisierte Mohr-Coulomb Versagenskriterien bestimmt, die sowohl in Hauptnormalspannungen als auch in Normal- und Scherspannungen angegeben werden. Ein Vergleich zeigt, dass es zwar für Klastika und Vulkanite aus Aufschlüssen möglich ist, Versagenskriterien, die in Hauptnormalspannungen ausgedrückt werden, auf Bohrkernproben anzuwenden, aber nicht für Karbonate. Sind die Versagenskriterien allerdings in Normal- und Scherspannungen angegeben, ist die Anwendbarkeit für alle Gesteinsarten gut. Eine Übertragbarkeit der empirischen Beziehungen auf die Tiefe wird abgeleitet. Die wichtigsten Parameter, um die Anwendbarkeit der Aufschlussdaten zu gewährleisten, sind eine vergleichbare Textur und eine ähnliche Porosität von Äquivalenzproben aus Steinbrüchen und Bohrkernproben. Die Bruchausbreitung infolge einer hydraulischen Stimulation von heterogenen Gesteinen wurde mit dem Programm FRACOD analysiert. Es wurden numerische Modelle erstellt, die für das NWGB charakteristisch sind und die sowohl geschichtete Abfolgen als auch bereits existierende Brüche berücksichtigen. Die Ergebnisse der Untersuchung von Bruchsystemen in Störungszonen und die gemessenen gesteinsmechanischen Eigenschaften werden als Eingangsparameter verwendet. Die Modellierung zeigt, dass ein großer mechanischer Kontrast zwischen einzelnen Schichten bezüglich Elastizitätsmodul und Poissonkoeffizient geringeren Einfluss auf die Ausbreitungsrichtung des Bruches hat, als stark unterschiedliche Bruchzähigkeiten. Werden bereits existierende Brüche in das Modell eingebaut, zeigt sich eine starke Wechselwirkung mit dem induzierten Hydrobruch. Die Ergebnisse dieser Doktorarbeit sind von vielfältigem Nutzen. Erstens helfen die Daten bei der Exploration von geothermischen Reservoiren in Störungszonen mit hohen natürlichen Permeabilitäten. Zweitens liefern die Ergebnisse der Labormessungen Aussagen und Ansätze, wie man die mechanischen Gesteinseigenschaften in größeren Tiefen anhand von Aufschlussproben vorhersagen und sie als Eingangsparameter für zukünftige numerische Modellierungen zu geothermischen Fragestellungen heranziehen kann. Außerdem liefert die numerische Modellierung der Bruchausbreitung infolge einer hydraulischen Stimulation in heterogenen Gesteinen Einblicke in die relevanten Parameter, die Einfluss auf die Ausbreitungsrichtung des induzierten Bruches haben. Dieses Wissen wird dabei helfen, die hydraulische Stimulation an die jeweiligen Reservoirbedingungen anzupassen.