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10th International Congress of the Brazilian Geophysical Society
- Conference date: 19 Nov 2007 - 23 Nov 2007
- Location: Rio de Janeiro, Brazil
- Published: 19 November 2007
61 - 80 of 484 results
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Análise da sensibilidade na determinação da porosidade e grau de saturação em DNAPL a partir da inversão das velocidades das ondas P, S e de Radar
More LessThis paper aims to analyze the sensibility of the simultaneous inversion of seismic and electromagnetic wave velocities in saturated porous media to estimate porosity and DNAPL concentration (dense nonaqueous phase liquids). We used numerical simulations. The solution of the inversion problem came from minimizing an objective function. The results pointed out that this approach is satisfactory for media with high porosity and DNAPL concentration. On the other hand, for sediments with low porosity and DNAPL concentration only the porosity value was possible to be estimated.
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Detecção de Contaminação de Solo e Água Subterrânea por Vinhaça através de Eletroresistividade e Polarização Induzida
Given the recent demand on ethanol manufacturing based on sugar cane, there has been a relative increase of the amount of the byproduct known as vinasse.It wellknow that, although its adequate use could improve the production of sugar cane, its overuse not only can decrease the production but also acts as a soil and groundwater contaminant. In this paper we present the results of geophysical investigations on soil fields and groundwater at the Sepé Tiarajú Camp located at the cities of Serrana and Serra Azul, SE Brazil, in order to verify a potential contamination caused by vinasse application. There were made three surveys where were applied the methods of eletroresistivity and induced polarization (IP) using the dipole-dipole array. The obtained results indicate a contamination focus on a site placed nine meters deep around a deactivated vinasse buried tank.
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Processamento e interpretação de dados aerogamaespectrométricos da bacia hidrográfica do rio São Domingos, noroeste do estado do Rio de Janeiro
In the present work we show the results of an airborne gamma-ray data processing and interpretation in the Northwestern portion of Rio de Janeiro State. The studied area is characterized by small private lands with a low-level technological agriculture soil handling techniques. Our results show that weathering processes may control the isotopes distribution in the region.
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Comparação de resultados de modelagens diretas e investigações elétricas 2D em área de depósito de resíduos urbanos
Authors S.J.S. Fachin, V.R. Elis, W.R. Borges, A.L. Lago, A.T. Ustra, I.M. Carlos, E.C. Santos and J. HigarashiThe use of direct and inverse modeling to planning geophysical investigations to provide the best field parameters. This work compares synthetic and real data electric resistivity 2D results obtained in the area of the antique landfill of Ribeirao Preto, Sao Paulo state. The results confirm the efficiency of the polo-dipole array in the identification of the limits and the ditches base of residues disposition and the find the zone of leachate flow.
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The Meteorology contribution to the Brazilian Energy Sector
This paper aims at presenting the main products of Solar and Wind Energy Resource Assessment (SWERA) project for Brazil and how this information on solar and wind energy resources can be used to spread out the energy production matrix improving the energy security and reducing the dependency on fossil fuels. The SWERA project were developed in Brazil under the coordination of Climate and Environmental Division of CPTEC/INPE and illustrates how the scientific research in meteorology and climatology can contribute to the energy planning and policies developed in Brazil. The products of SWERA project include information that will be extremely useful to foster capital investments providing private sector and government institutions with reliable database of energy resources. The paper presents the main results in solar and wind energy mapping and discusses some renewable energy scenarios taking in account the technologies in use currently.
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Variação Climática Secular e Mapeamento do ‘Efeito Estufa’ no Território Brasileiro
More LessBorehole temperature data from the eastern parts of Brazil has been examined in an attempt to extract information on surface thermal perturbations of the recent past at low latitudes. Forward models were employed in the analysis of temperature logs from 29 localities and, in addition, inverse modeling was carried out for data from 10 selected sites. The model results have allowed determination of the magnitude as well as the duration of ground surface temperature (GST) changes in five major geographic zones of Brazil. Prominent among such events are the warming episodes that occurred over much of the subtropical highland regions in the southeastern parts of Brazil. The present magnitude of GST changes in this region are in the range of 2 to 3.5oC but have had their beginning during the early decades of the 20th century. Nearly similar trends are also seen in temperature-depth profiles of bore holes in the subtropical humid zones of the interior parts of southern Brazil. In the coastal areas however, the magnitudes of surface warming are relatively smaller (falling in the range of 1.7 to 2.2oC) while its beginning appears to have shifted to the mid decades of the 20th century. The data from semi arid zones of northeast Brazil also indicate occurrence of surface warming events but the magnitudes are in the range of 1.4 to 2.2oC while the duration of the warming event is larger, extending back into the last decades of the 19th century. The present work also includes preliminary inferences on GST variations in the northern tropical regions of Brazil, based on analysis of borehole data in shallow wells at two localities: Belém (state of Pará) and Manaus (state of Amazon). Surface temperature changes inferred for these localities are relatively small, being less than 1oC in areas where the
vegetation cover has been removed. In areas of tropical rain forest GST changes are found to be less than 0.5oC. There are indications that changes in both climate and vegetation cover contribute to variations in GST. Another important result emerging from model studies is that the climate was relatively cooler during the 17th and 18th centuries. The climate histories, deduced from geothermal data, are found to be consistent with results of available meteorological records in southern Brazil. Comparative studies also indicate that the magnitudes and duration of recent climate changes in southern and eastern Brazil are similar to those found in other continental areas such as North America, Asia and Europe.
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Caracterização da pluma de Contaminação de Al e Pb através do método da eletroresitividade no Município do Rio de Janeiro –RJ
More LessThis paper presents a characterization of plume of contamination of “ Al “ and “ Pb” in soil study, carried out with the Resistivity Method. This study was made before of the construction of a building in the District Colégio at County of Rio de Janeiro. The site there was a Industry of the Galvanoplastic. In principle was investigated by conventional borings , and detected Al (Aluminium) and Pb (lead) in analysis of soil, the electral method were evaluated for the capacity to detect the interfaces between different layers, in particular the plume soil-contamination. The data obtained with the configuration Wenner, the data obtained with the electrica were satisfatory. The resistivity method produced other interesting data and corroborated with the interpretation of the subsoil.
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Preliminary results of Electrical Resistivity Tomography applied to a feedlot to detect conductivity anomalies
Authors Claudia Sanato, Beatriz Losinno and Horacio MallevilleThe intensive animal production is considered highly risky for groundwater and soil.
The aim of this work was to obtain an electrical conductivity image of unsaturated and saturated zone at a feedlot (cattle feeding field) at the surroundings of Buenos Aires city (Argentina) in order to detect the most critical sectors of the field, respecting contamination by animal wastes. Dipole-dipole electrical soundings (electrical resistivity tomography) were performed at the corral zone and the surroundings. 2D models of conductivity were obtained with the UBCGIF software.
Even if there is a calcareous plate bellow the corral soils, vertical infiltration or subsurface runoff may have occurred since these sites show conductivities three times higher than the surroundings (greater than 1600 μS/cm) up to a depth of 10 m, particularly near a small channel of effluents. The models showed higher conductivities in the direction of groundwater flow and decreasing topography, allowing further designs of soil sampling and infiltration experiments.
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Geoelectrical observations at the mining dumps of the Peña de Hierro copper mine in the Rio Tinto mining district / Spain
Detailed geoelectrical measurements reveal a 3D-resistivity model of the internal structures of a heap of mining residuals dumped at the abandoned copper mine Peña de Hierro which is located at the headwaters of the Rio Tinto in Spain. The model reveals also the relief of the bedrock underlying the heap. Aspects of water movement at the surface are investigated by an artificial precipitation experiment with monitoring the subsequent changes of resistivities. The investigation is part of a research project dedicated to the role of hard pan formation with respect to natural reduction of acid mine drainage, funded by the German Federal Ministry for Education and Research.
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Geophysical characterisation of an abandoned waste disposal site near an area of environmental interest
Authors G.P. Deidda, F. Loddo, C. Piga and G. RanieriSolid waste disposal represents an urgent problem for public administrations worldwide. Today in Italy more than 58% is deposited in landfill sites. The examination of possibly appropriate landfill sites together with the discovering of the abandoned waste disposal of those already employed for this purpose and their reclamation is therefore a primary issue. In the present paper a geophysical characterisation of an abandoned waste disposal situated in the Central-Eastern part of Sardinia, near the town of Tortolì, is presented. The geophysical survey allowed to delineate the different parts of the landfill and to calculate their volumes and individuate the plume of leachate.
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Caracterização preliminar da área da lixeira de Porto Velho – RO empregando o método eletroresistividade
Geophysical experiments using eletroresistivity method, by means of vertical electrical sounding and electric profiling (Shulumberger and dipole-dipole configurations), were done at the municipal “landfills” of the cities of Porto Velho, Rondônia. These studies were done in order to identify the anomalies of the local underground. The regional geology, which crop out at the Porto Velho sites, is caracterized by immature laterites, pleitocenic age, seated on rocks granities of the formation Santo Antônio, that surfaces in the area of the embankment of Porto Velho. The integration of eletroresistivity and local geology, allowed starting from interpreted geoelectric models and permits the determination of the leachate percolation zones, identify the different lithotypes of the underground, analyze the behavior of the feather of chorume contamination and direction of the groundwater.
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Uso Do SBP (Sub Bottom Profiler) 3,5kHz No Mapeamento Do Substrato De Uma Lagoa De Descarte De Efuentes Industriais
This paper presents the results of an SBP (Sub Bottom Profiler) application for sedimentary and environmental evaluation in a hydrocarbon industrial saline lake.
The SBP allows the bathymetry mapping, making images of the sedimentary geometry as well as identifying the acoustic anomalous zones related to the hydrocarbon contamination. A case history in a new 3D approach presented here, indicates this methodology as a strong tool for geophysical and geological evaluation in a saline water and clay environment.
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Tomografia Elétrica Entre Poços na Investigação Ambiental de Sítios Contaminados por Hidrocarbonetos e Água Salinizada
The usual electrical multielectrode methods can be replaced by the cross-hole multielectrode one (borehole electrical tomography), with advantages in terms of apparent resistivity measurement precision, depth of investigation and space restriction areas with a large amount of surface interferences. This paper shows the applications of the electrical borehole tomography considering three different sites: the first one representing a free phase hydrocarbon resistive contamination, the second one representing a dissolved hydrocarbon phase conductive contamination and the third one presenting a salt water conductive contamination. The geophysical result was correlated with well logging, geochemistry and hydrochemistry analysis and can confirm this methodology as a powerful tool when applied to the environmental evaluation.
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Uses, abuses, and examples of seismic-derived acoustic impedance data: What does the interpreter need to know?
More LessThroughout the years there has been a concerted effort to integrate the geoscience disciplines to become more adept at understanding the hydrocarbon potential of a given area. In the 1980s, geophysicists interpreted 2D seismic data by overlaying well log data on paper seismic sections and using generalized depth-to-time curves to determine which events represented markers on the logs. Geologists interpreted cross-sections by drawing straight lines between wells to represent their correlations. Because technology advances have changed the process, many people today have become “interpreters” of 2D or 3D data on workstations where the log data, seismic data, and many derivations of the seismic data (attributes, coherence, P impedance, inversions, elastic impedance, lambda rho, etc.) are available to fine-tune the analysis process. The question, however, still remains: Are we integrating the data yet?
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Seismic Stratigraphy of Pre-Salt in the Southernmost of Santos Basin
Authors Márcia Kuhn Karam, Roberto Porto and Makoto SaitoThe evaluation of Pre-Salt in the Southernmost of Santos Basin using 2D and 3D seismic data reveals that there are three seismic stratigraphic sequences compounded by (1) a lower volcanic rocks sequence, (2) an intermediate sequence where half grabens predominate, related to an intense period of tectonic activity and (3) the upper sequence characterized by tectonic quiescence identified as Sag Phase. It is suggested that the two first sequences would be related to rifting events (Rift Sequence) and the third would belong to Transitional Sequence including the upper part of Guaratiba Formation. In this last sequence began the thermal subsidence.
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Detailed seismic exploration of the Orelka monocline, Ukraine – a case study
Authors Viktor Mershchiy, Olga Mershchiy and Myroslav DmitrovskyIn spite of the fact that Ukraine is one of the oldest oil producing regions, the oil and gas production in Ukraine provides a national industry only partially and for the most part depends on the import. Practically all traditional traps of oil and gas in Ukraine are already striked and are in exploitation. Therefore the main task of seismic survey on oil and gas fields are the exploration of non-conventional traps, situated, in particular, on the vast monoclines of large-scale basins. In the given report we consider the successful seismic survey on a monoclinal slope of Dnieper-Donetsk basin (DDB), Ukraine, as an example.
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Building Time-Depth Curves: The Shift/Drift Methodology
More LessThe Checkshot is a well acquisition technique whose data are used to try to establish a correlation among depth of geological layers in well to the time of seismic events in a seismic section. In a petroleum company, it is a routine to discuss about bad quality in seismic to well correlation, regardless the commercial tool in use. This correlation may be done by using synthetic seismograms. The first perception trying to do this correlation is that there is a time shift that must be solved. In general this time shift may be observed correlating good geological markers that are also good seismic events: the time of events in seismic section doesn’t agree with the time of checkshot readings. By the time the initial correlation is assumed good enough, the technician involved in the task may note also that there is an increasing uncoupling among geological markers and seismic events, starting from the initial point of correlation. Also it is easy to observe that amplitude, frequency and phase of seismic events doesn’t match the same properties in the synthetic seismogram. The scope of this paper is to investigate and establish an acceptable solution to the correlation between geological markers in well and the correlative seismic events in seismic section.
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Integration of surface and subsurface data to optimize G&G interpretation workflow
More LessGeologic and Geophysics (G&G) interpretations typically use only seismic data in planning for the development of oil and gas prospects. However, the integration of seismic data with aerial photography and satellite images, for example, in the same workflow can reduce the time needed to obtain environmental approvals for proposed onshore well locations. Due the short time required to fulfill exploratory concession contracts, a shorter overall approval cycle is crucial. The integration of these two major sources of pertinent data — seismic and aerial — is capable of reducing the overall cycle time by at least 50 percent, besides being able to reduce costs and safety risks.
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Estudos geofísicos integrados na região da Bacia de Lajeado na Faixa Apiaí, sudoeste de São Paulo, Brasil
Authors Mario Jesus Tomas Rosales and Wladimir ShukowskyTerrestrial gravity and airborne magnetic data covering an area of approximately 4000 km2 were used to refine the existing geological mapping of the Apiaí Belt, as a contribution to the detailed geological knowledge of the differents litologies that constitute the Lajeado basin, as well as of its tectonic setting. The terrestrial gravity and aeromagnetic data were interpreted qualitatively, using techniques of filtering and transformation of the potential, and quantitatively, by 2.5 D modeling along regional geophysical profiles.
The main result is the structural characterization for the presence of thick packages of metasedimentary and volcano-sedimentary rocks and, with intercalations of metabasites to the Lajeado sub-group (VL) that amounts an estimated thickness of approximately 3 km.
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Geophysical properties associated to Juá District geology, Ceará, Brazil
Airborne magnetic and electromagnetic highresolution data were processed to unveil physical properties of Pre-Cambrian high-grade terrains in Northeast Brazil. The method followed the common data correction plus, map and profile interpretation, ending with spatial analysis by probability ratio technique. Local geologic map and, lineament interpretation complete the data set. Results show a geophysical differentiation exclusive for some rock units and, boundaries were redefined improving the geologic map. Also, shallow and deep structures were distinguished
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