Geological Facies Recovery Based on Weighted $$\ell _1$$ ℓ 1 -Regularization     

Calderon  Hernan  Santibañez  Felipe  Silva  Jorge F.  Ortiz  Julián M.  Egaña  Alvaro 《Mathematical Geosciences》2020,52(5):593-617

Mathematical Geosciences - A weighted compressed sensing (WCS) algorithm is proposed for the problem of channelized facies reconstruction from pixel-based measurements. This strategy integrates...  相似文献   

Climatic signals in lacustrine deposits of the Upper Yacoraite Formation,Western Argentina: Evidence from clay minerals,analcime, dolomite and fibrous calcite     

João Paulo B. Gomes  Rodrigo B. Bunevich  Sandra N. Tonietto  Daisy B. Alves  Julice F. Santos  Fiona F. Whitaker 《Sedimentology》2020,67(5):2282-2309

Authigenic clays are an important control on reservoir quality in lacustrine carbonates but remain challenging to predict. Lacustrine depositional systems respond to climatic variations in rainfall, surface runoff and groundwater input, and evaporation, and result in rapid and frequent changes in lake volume; this is expressed through changing water depth and shoreline position. In the upper portion of the Early Palaeocene Yacoraite Formation of the Salta Basin in Argentina, extensive lacustrine deposits were deposited during the sag phase of rifting. Prior high-resolution stratigraphic studies have suggested that climatic factors control microbial carbonate sequences within a ‘balanced fill’ lake, with variation in the lake level having a major influence on facies association changes. This study characterizes the evolution of facies and mineralogy within the Yacoraite Formation, focusing on the distribution of clay minerals, making a link between the high, medium and low-frequency sequence stratigraphic cycles. The low-frequency transgressive hemicycle of the upper portion of the Yacoraite Formation is comprised of abundant siliciclastic facies, suggesting a wetter period. Microbialites occurring in this interval are coarse-grained and agglutinated. Detrital clay minerals such as illite and chlorite and associated siliciclastic sediments were input to the lake during high-frequency transgressive periods. During high-frequency regressive hemicycles, sedimentation was dominated by carbonate facies with Ca-rich dolomite and the authigenic clays are comprised of chlorite/smectite mixed-layers. By contrast, the low frequency regressive hemicycle records fine-grained agglutinated microbialite with horizons of fibrous calcite, more stoichiometric dolomite, barite and authigenic magnesian smectite. This indicates elevated ion concentrations in the lake under intense evaporation during an arid period. Understanding the conditions that are favourable for formation and preservation of authigenic clays within the lacustrine environment can improve understanding of reservoir quality in comparable economically important deposits.  相似文献   

Application of open tools and datasets to probabilistic modeling of road traffic disruptions due to earthquake damage     

Catarina Costa  Rui Figueiredo  Vitor Silva  Paolo Bazzurro 《地震工程与结构动力学》2020,49(12):1236-1255

The disruption of a transportation network can have a high social and economic impact on the welfare of a society, as it can significantly affect the daily routines of a community. Although many studies have focused on the estimation of physical risk in the components that compose these networks, only a limited number have analyzed their interconnections and impact in the traffic flow. The present study analyzes how earthquake damage can disrupt the road network in an urban environment, and how this will influence the ability of the population to travel. Traffic due to daily commutes is modeled for different layouts of the network, corresponding to possible disruptions caused by earthquake damage. The duration and length of each trip were calculated both for the undamaged network conditions and for the disrupted network. The increase in the median duration and length of each trip allows estimating the economic loss for each event due to drivers' delay. By combining the probability of a specific road being blocked with its number of users, the average number of affected vehicles was estimated, and the most critical segments identified. The methodology was applied to a case study concerning the road network of the area around the Italian city of Messina in Sicily. The results were calculated for both a repetition of the well-known historical event of 1908 and a set of simulated earthquakes consistent with the national probabilistic seismic hazard model of Italy.  相似文献   

Separation of PP- and PS-wave reflected seismic data using two-dimensional finite offset common-reflection-surface traveltime approximation     

Raphael Di Carlo Silva dos Santos  João Carlos Ribeiro Cruz  Manuel de Jesus dos Santos Costa 《Geophysical Prospecting》2020,68(7):2046-2063

Recently, the interest in PS-converted waves has increased for several applications, such as sub-basalt layer imaging, impedance estimates and amplitude-versus-offset analysis. In this study, we consider the problem of separation of PP- and PS-waves from pre-stacked multicomponent seismic data in two-dimensional isotropic medium. We aim to demonstrate that the finite-offset common-reflection-surface traveltime approximation is a good alternative for separating PP- and PS-converted waves in common-offset and common shot configurations by considering a two-dimensional isotropic medium. The five parameters of the finite-offset common-reflection-surface are firstly estimated through the inversion methodology called very fast simulated annealing, which estimates all parameters simultaneously. Next, the emergence angle, one of the inverted parameters, is used to build an analytical separation function of PP and PS reflection separation based on the wave polarization equations. Once the PP- and PS-converted waves were separated, the sections are stacked to increase the signal-to-noise ratio using the special curves derived from finite-offset common-reflection-surface approximation. We applied this methodology to a synthetic dataset from simple-layered to complex-structured media. The numerical results showed that the inverted parameters of the finite offset common-reflection-surface and the separation function yield good results for separating PP- and PS-converted waves in noisy common-offset and common shot gathers.  相似文献   

Estimating free parameters in 2D inversion: example of gravity inversion in a rifted basement     

João B.C. Silva  Darcicléa F. Santos  Daniele P. Monteiro 《Geophysical Prospecting》2020,68(3):1057-1071

We advance a principle directed to assigning numerical values to free parameters usually present in inversion methods. It may be formulated as: ‘Optimum estimates of free parameters in an inversion procedure must lead, in tests using synthetic data, to solutions whose geometrical expression reflects the main qualitative or semiquantitative geological characteristic of the study area.’ To this end, the interpreter should (i) specify a typical anomalous source geometry which incorporates the most relevant geological information for the study area, (ii) compute the corresponding gravity anomaly and (iii) invert the anomaly for the source geometry finding the numerical values of the free parameters that lead to a solution closest to the typical source. Application of the above methodology to synthetic and real data from the basement relief of a rift basin has asserted its efficacy.  相似文献   

Numerical homogenization-based seismic assessment of an English-bond masonry prototype: Structural level application     

Luís C. Silva  Paulo B. Lourenço  Gabriele Milani 《地震工程与结构动力学》2020,49(9):841-862

A multiscale strategy is evaluated at a structural level for the analysis of unreinforced masonry structures. The mechanical characterization of the masonry is deduced from homogenization-based micro-scale finite element (FE) models. The derived data are here employed at a structural level via a discrete FE model. The discrete FE model is composed of quadrilateral rigid plates interconnected through vertical and horizontal interfaces. On the interfaces, between adjoining discrete elements, a model that accounts for the in- and out-of-plane behavior of masonry, with damage and plasticity, is adopted. Such interfaces represent the material pre- and post-peak regimes, its orthotropy, and, depending on the micro-model assumed, account by three-dimensional shear effects that are especially important for multi-leaf walls and complex regular textures. The discrete model has been implemented in an advanced structural analysis software where powerful built-in features as the arc-length method, line-search algorithm, and implicit or explicit solver schemes are available. The multi-scale model is applied for the dynamic study of a small English-bond masonry house prototype subjected to a series of consecutive earthquake records. Detailed comparisons between the experimental and numerical data are presented, including the results obtained through a continuous total strain rotating crack model. Quasi-static and dynamic analyses are conducted. Results demonstrate that when enough experimental information is available on the masonry components under tension, shear, and compression regimes, the approach predicts well the seismic structural response in terms of time-history displacements, seismic capacity, and damage patterns. The required computational cost (CPU time) is very attractive.  相似文献   

Pseudo- and real-inverted metamorphism caused by the superposition and extrusion of a stack of nappes: a case study of the Southern Brasília Orogen,Brazil     

da Motta  Rafael Gonçalves  Moraes  Renato 《International Journal of Earth Sciences》2017,106(7):2407-2427

International Journal of Earth Sciences - The Southern Brasília Orogen is a Neoproterozoic belt that occurs along the southernmost border of the São Francisco Craton where the...  相似文献   

Soil contamination by metals with high ecological risk in urban and rural areas     

F. B. V. da Silva  C. W. A. do Nascimento  P. R. M. Araújo  F. L. da Silva  L. H. V. Lima 《International Journal of Environmental Science and Technology》2017,14(3):553-562

Industrial development, intensive agriculture and fast urbanization have caused the metal contents of soils to increase to many times the allowable limits. To assess this impact on urban and rural soils, we quantified the Cd, Cr, Cu, Pb, Ni and Zn contents of 258 soil samples from the Recife metropolitan region (RMR). The objectives of the study were to estimate the probability of ecological risk, to determine the spatial pattern of the metals’ accumulation in the soil and to identify potential sources for the metals using a multivariate geostatistical approach. Mean concentrations of Zn, Cr, Pb, Cu, Ni and Cd in soils were 65.2, 17.9, 16.5, 12.8, 6.3 and 1.5 mg kg^?1, respectively. The results demonstrated that the Cd was anthropogenic in origin, the Cr and Ni were lithogenic (natural) in origin and the Cu, Pb and Zn were mixed in origin. Cd contaminated 91% of the samples; the median content of Cd (1.4 mg kg^?1) was three times the quality reference value for soil. The Cd contents of sugarcane fields exceeded the allowable limit (3.0 mg kg^?1) for agricultural areas. The spatial variability of the metals in the RMR showed that metallurgy, cement production, vehicle exhaust and vehicular traffic were the main sources of metals in urban areas, while phosphate-based fertilizers were the main sources in rural areas. More than 80% of the metropolitan region surveyed in the study was at moderate to high ecological risk.  相似文献   

Supportive elements to the decision-making process in the emergency planning of the Angra dos Reis Nuclear Power Complex,Brazil     

Corbiniano Silva  Luiz Claudio Gomes Pimentel  Luiz Landau  Paulo Fernando Lavalle Heilbron Filho  Fabiana Guimarães Resende Gobbo  Pryscila de Jesus de Sousa 《Environmental Earth Sciences》2017,76(3):133

Accidents in nuclear power plants are problems of great complexity, mainly due to their consequences, such as the population evacuation from the enterprise influence area. The decision-making and emergency plans must be well articulated and require good local geographic space knowledge and the interactions of their environments. This study is a contribution to the emergency plans for the Almirante Álvaro Alberto Nuclear Power Plant, currently the only nuclear complex in Brazil, located in Angra dos Reis, Rio de Janeiro. The study confirmed the region’s main geoenvironmental aspects as winds and rainfall, landslides and population density were evaluated as important elements in the local emergency process. Their integrated analysis supported scenario identification and critical regional points and highlighted population evacuation escape routes. These important results characterized the support to local emergency management actions and guidelines. Furthermore, the geographic information systems was configured as an integrated spatial and temporal analysis platform to associate meteorological, geological/geomorphological and socio-economic data, playing a key role to support the evacuation planning in the event of nuclear power plant accidents.  相似文献   

Sensitivity of the elastic anisotropy and seismic reflection amplitude of the Eagle Ford Shale to the presence of kerogen          下载免费PDF全文

Colin M. Sayers  Shiguang Guo  Josimar Silva 《Geophysical Prospecting》2015,63(1):151-165

The Eagle Ford Shale of Central and South Texas is currently of great interest for oil and gas exploration and production. Laboratory studies show that the Eagle Ford Shale is anisotropic, with a correlation between anisotropy and total organic carbon. Organic materials are usually more compliant than other minerals present in organic‐rich shales, and their shapes and distribution are usually anisotropic. This makes organic materials an important source of anisotropy in organic‐rich shales. Neglecting shale anisotropy may lead to incorrect estimates of rock and fluid properties derived from inversion of amplitude versus offset seismic data. Organic materials have a significant effect on the PP and PS reflection amplitudes from the Austin Chalk/Upper Eagle Ford interface, the Upper Eagle Ford/Lower Eagle Ford interface, and the Lower Eagle Ford/Buda Limestone interface. The higher kerogen content of the Lower Eagle Ford compared with that of the Upper Eagle Ford leads to a negative PP reflection amplitude that dims with offset, whereas the PS reflection coefficient increases in magnitude with increasing offset. The PP and PS reflection coefficients at the Austin Chalk/Upper Eagle Ford interface, the Upper Eagle Ford/Lower Eagle Ford interface, and the Lower Eagle Ford/Buda Limestone interface all increase in magnitude with increasing volume fraction of kerogen.  相似文献