On the risk of hydraulic fracturing in CO2 geological storage          下载免费PDF全文

Panos Papanastasiou  Euripides Papamichos  Colin Atkinson 《国际地质力学数值与分析法杂志》2016,40(10):1472-1484

We present a contribution on the risk of hydraulic fracturing in CO₂ geological storage using an analytical model of hydraulic fracturing in weak formations. The work is based on a Mohr–Coulomb dislocation model that is extended to account for material with fracture toughness. The complete slip process that is distributed around the crack tip is replaced by superdislocations that are placed in the effective centers. The analytical model enables the identification of a dominant parameter, which defines the regimes of brittle to ductile propagation and the limit at which a mode‐1 fracture cannot advance. We examine also how the corrosive effect of CO₂ on rock strength may affect hydraulic fracture propagation. We found that a hydraulically induced vertical fracture from CO₂ injection is more likely to propagate horizontally than vertically, remaining contained in the storage zone. The horizontal fracture propagation will have a positive effect on the injectivity and storage capacity of the formation. The containment in the vertical direction will mitigate the risk of fracturing and migration of CO₂ to upper layers and back to the atmosphere. Although the corrosive effect of CO₂ is expected to decrease the rock toughness and the resistance to fracturing, the overall decrease of rock strength promotes ductile behavior with the energy dissipated in plastic deformation and hence mitigates the mode‐1 fracture propagation. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Discussion to the article Characteristic limitations of advanced plasticity and hypoplasticity models for cyclic loading of sands,by J. Duque $$\cdot$$ M. Yang $$\cdot$$ W. Fuentes $$\cdot$$ D. Maš’in $$\cdot$$ M. Taiebat     

Kolymbas  Dimitrios 《Acta Geotechnica》2023,18(1):581-583

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P-T estimates and timing of the sapphirine-bearing metamorphic overprint in kyanite eclogites from Central Rhodope, northern Greece     

Evangelos Moulas  Dimitrios Kostopoulos  James A. D. Connolly  Jean-Pierre Burg 《Petrology》2013,21(5):507-521

Sapphirine-bearing symplectites that replace kyanite in eclogites from the Greek Rhodope Massif have previously been attributed to a high-pressure granulite-facies metamorphic event that overprinted the eclogitic peak metamorphic assemblage. The eclogitic mineralogy consisted of garnet, omphacitic pyroxene, rutile and kyanite and is largely replaced by low-pressure minerals. Omphacite was initially replaced by symplectites of diopside and plagioclase that were subsequently replaced by symplectites of amphibole and plagioclase. Garnet reacted during decompression to form a corona of plagioclase, amphibole and magnetite. Rutile was partly transformed to ilmenite and kyanite decomposed to produce a high-variance mineral assemblage of symplectitic spinel, sapphirine, plagioclase and corundum. The presence of quartz and corundum in the kyanite eclogites is evidence for the absence of bulk equilibrium and obviates a conventional analysis of phase equilibria based on the bulk-rock composition. To circumvent this difficulty we systematically explored the pressure-temperature-composition (P-T-X) space of a thermodynamic model for the symplectites in order to establish the pressure-temperature (P-T) conditions at which the symplectites were formed after kyanite. This analysis combined with conventional thermometry indicates that the symplectites were formed at amphibolite-facies conditions. The resulting upper-pressure limit (～0.7 GPa) of the sapphirine-producing metamorphic overprint is roughly half the former estimate for the lower pressure limit of the symplectite forming metamorphic event. Temperature was constrained (T ～ 720°C) using garnet-amphibole mineral thermometry. The P-T conditions inferred here are consistent with thermobarometry from other lithologies in the Rhodope Massif, which show no evidence of granulite-facies metamorphism. Regional geological arguments and ion-probe (SHRIMP) zircon dating place the post-eclogite-facies metamorphic evolution in Eocene times.  相似文献   

Assessment of flood hazard based on natural and anthropogenic factors using analytic hierarchy process (AHP)   总被引：5，自引：3，他引：2  

Stefanos Stefanidis  Dimitrios Stathis 《Natural Hazards》2013,68(2):569-585

Flooding is the most common natural hazard in Greece, and most of low-lying urban centers are flood-prone areas. Assessment of flood hazard zones is a necessity for rational management of watersheds. In this study, the coupling of the analytical hierarchy process and geographical information systems were used, in order to assess flood hazard, based either on natural or on anthropogenic factors. The proposed method was applied on Kassandra Peninsula, in Northern Greece. The morphometric and hydrographic characteristics of the watersheds were calculated. Moreover, the natural flood genesis factors were examined, and subsequently, the anthropogenic interventions within stream beds were recorded. On the basis of the above elements, two flood hazard indexes were defined, separately for natural and anthropogenic factors. According to the results of these indexes, the watersheds of the study area were grouped into hazard classes. At the majority of watersheds, the derived hazard class was medium (according to the classification) due to natural factors and very high due to anthropogenic. The results were found to converge to historical data of flood events revealing the realistic representation of hazard on the relating flood hazard maps.  相似文献   

Shear Strength of Sands Reinforced with Polypropylene Fibers     

Costas A. Anagnostopoulos  Theodosios T. Papaliangas  Dimitrios Konstantinidis  Christos Patronis 《Geotechnical and Geological Engineering》2013,31(2):401-423

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An efficient method for estimating the collapse risk of structures in seismic regions   总被引：1，自引：0，他引：1  

Laura Eads  Eduardo Miranda  Helmut Krawinkler  Dimitrios G. Lignos 《地震工程与结构动力学》2013,42(1):25-41

Assessing the probability of collapse is a computationally demanding component of performance‐based earthquake engineering. This paper examines various aspects involved in the computation of the mean annual frequency of collapse (λ_c) and proposes an efficient method for estimating the sidesway collapse risk of structures in seismic regions. By deaggregating the mean annual frequency of collapse, it is shown that the mean annual frequency of collapse is typically dominated by earthquake ground motion intensities corresponding to the lower half of the collapse fragility curve. Uncertainty in the collapse fragility curve and mean annual frequency of collapse as a function of the number of ground motions used in calculations is also quantified, and it is shown that using a small number of ground motions can lead to unreliable estimates of a structure's collapse risk. The proposed method is shown to significantly reduce the computational effort and uncertainty in the estimate. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Kos Plateau Tuff (KPT) on Kalymnos island, Aegean volcanic arc: A geochemical approach     

Dimitrios Zouzias  Karen St. Seymour 《Journal of Volcanology and Seismology》2013,7(5):293-312

Thirteen pumice samples from the D and E ignimbrite units of Kalymnos Tuff have been analyzed for their biotite and feldspar phenocryst mineral chemistry and for bulk major and 20 trace, including 14 Rare Earth elements, to define and compare their petrochemistry with the Kos Plateau Tuff (KPT). For the same purpose major element analyses were obtained from Kalymnos Tuff and KPT glasses. Both KPT and Kalymnos pumice lapilli are rhyolites characterized by a well-developed ‘silky’ texture and roundish quartz. Phenocrysts of biotite and feldspars (sanidine, oligoclase) from both tuffs display compositional overlap. Crystals are charac-terized by undulatory extinction (quartz), fractures (sanidine, oligoclase) and bent cleavages (biotite) due to the explosive origin of their host. Both tuffs show well-defined petrogenetic trends and extensive compositional overlaps on major and trace element variation diagrams suggesting that they are consanguineous. However, D ignimbrite samples are more evolved than those obtained from E ignimbrite as indicated from major elements, alkali earths (Ba, Rb, Sr), immobile (Zr, Y), compatible (V) and hygromagmatophile trace element (Th) distributions. This evidence indicates a stratified magma chamber under a ～16 Km caldera superstructure which is mostly submarine.  相似文献   

RETRACTED ARTICLE: A catalog of aftershock sequences in Greece (1998–2008) and their spatial and temporal characteristics     

Ioannis Baskoutas  Dimitrios Papanastassiou 《Journal of Seismology》2013,17(3):1107-1107

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Rutile chemistry and thermometry as provenance indicator: An example from Chios Island,Greece     

Guido Meinhold  Birte Anders  Dimitrios Kostopoulos  Thomas Reischmann 《Sedimentary Geology》2008,203(1-2):98-111

In the present study we focused on detrital rutile separated from 12 psammitic samples that belong to three different sedimentary successions (Carboniferous, Permo-Carboniferous, Permo-Triassic) occurring on Chios Island, Greece. The Ti, Cr, Al, Fe, Nb, Zr, Si, and V contents of the rutiles were obtained by electron-microprobe analyses to trace their provenance.The Cr and Nb concentrations of the analysed rutile grains show a wide range and indicate that this mineral in the Carboniferous succession is mainly derived from metamafic rocks, whereas in the Permo-Carboniferous and Permo-Triassic successions stem from a metapelitic source. The calculated formation temperatures using the Zr-in-rutile thermometer range from ca. 520 to 850 °C with “hotter” rutile being encountered in the Permo-Carboniferous and Permo-Triassic successions. This feature together with the rutile chemistry indicate a change in source-rock lithology through time, which could either reflect an increasing depth of erosion of an exhumed ‘Variscan’ nappe pile of heterogeneous composition in the hinterland or a change in the style of accretion and erosion of different terranes at the southern margin of Laurussia during the subduction of a branch of the Palaeotethys Ocean in the Late Palaeozoic. In general, this study underscores the importance of rutile chemistry and thermometry in quantitative single-mineral provenance analysis and in chemostratigraphic analysis of clastic sedimentary rocks.  相似文献   

Analysis of precipitation extremes based on satellite (CHIRPS) and in situ dataset over Cyprus     

Katsanos  Dimitrios  Retalis  Adrianos  Tymvios  Filippos  Michaelides  Silas 《Natural Hazards》2016,83(1):53-74

A study of a daily precipitation database for the island of Cyprus is performed for a period of 30 years. A number of climatic indices for precipitation are calculated using the recently available CHIRPS dataset, on high spatial (0.05°) and temporal (daily) resolution. The same parameters for the same time period (1981–2010) are then calculated using the dense network of rain gauges of the Cyprus Department of Meteorology. The results show a quite promising performance regarding indices related to daily precipitation thresholds, resulting in high correlation scores. In the case of indices referring to number of days, it seems that the results are ambiguous, with medium or no correlation, probably related to the criteria used for the identification of a wet (rainy) day on the CHIRPS dataset.  相似文献