Interpretação sísmica e análise de atributos - área do levantamento sísmico 3D de siririzinho (Bacia Sergipe-Alagoas, NE do Brasil)

The main objective of the present thesis was the seismic interpretation and seismic attribute analysis of the 3D seismic data from the Siririzinho high, located in the Sergipe Sub-basin (southern portion of Sergipe-Alagoas Basin). This study has enabled a better understanding of the stratigraphy and structure that the Siririzinho high experienced during its development. In a first analysis, we used two types of filters: the dip-steered median filter, was used to remove random noise and increase the lateral continuity of reflections, and fault-enhancement filter was applied to enhance the reflection discontinuities. After this filtering step similarity and curvature attributes were applied in order to identify and enhance the distribution of faults and fractures. The use of attributes and filtering greatly contributed to the identification and enhancement of continuity of faults. Besides the application of typical attributes (similarity and curvature) neural network and fingerprint techniques were also used, which generate meta-attributes, also aiming to highlight the faults; however, the results were not satisfactory. In a subsequent step, well log and seismic data analysis were performed, which allowed the understanding of the distribution and arrangement of sequences that occur in the Siririzinho high, as well as an understanding of how these units are affected by main structures in the region. The Siririzinho high comprises an elongated structure elongated in the NS direction, capped by four seismo-sequences (informally named, from bottom to top, the sequences I to IV, plus the top of the basement). It was possible to recognize the main NS-oriented faults, which especially affect the sequences I and II, and faults oriented NE-SW, that reach the younger sequences, III and IV. Finally, with the interpretation of seismic horizons corresponding to each of these sequences, it was possible to define a better understanding of geometry, deposition and structural relations in the area.

Caracterização morfológica e sedimentar do talude continental (foz do Amazonas)

Created on 3 december 1997, the REMPLAC (Program for Assessment of Mineral Potencial of the Continental Shelf), this porgram aimed to make the basic survey, systematic geological and geophysical continental shelf, detail, at an appropriate scale, sites geo-economic, and perform the analysis and evaluation of mineral deposits. The REMPLAC should continue the efforts of Global Recognition Program of the Brazilian Continental Margin REMAC closed in 1978, the operations Geophysical Sea (GEOMAR) developed by the Directorate of Hydrography and Navigation and the various initiatives of the Program of Marine Geology and Geophysics (PGGM). Despite the high interest on the Amazon platform, there is little information o their morphology and sediment characterization, and in order to fill this gap, the present work samples sedimentological point followed by seismic acquisition. And the studies were to characterize the possible area of interest as being directly influence by tides, which sediments are reworked throughout the platform featuring grain angle with sharp corners, and the carbonate content increases as it approaches the breakdown the platform, and the bodies found outside the foraminifera and mollusks. However, diverging with organic matter that reduces its concentration as it moves away from the coast. The seismic profiles do not get satisfactory results because of low visibility, however, to correlate with the spot samples, of sediment were possible morphological characterization of the area.

Estruturação litosférica da Província Borborema ao longo da Transecta Angüera (BA) Macau (RN), com base em dados gravimétricos

Since 2005, geophysical surveys have been carried out in the Precambri-an Borborema Province, along two transects with 800 km long each one. A pool of Brazilian public universities and institutions has been acquired deep refrac-tion seismic, gravity and magnetotelluric, with the purpose to model the conti-nental lithosphere of the region. This paper present the gravity survey of the second transect, that crosses the Borborema Province from SW to NE, passing through the São Francisco Craton, Transversal and Meridional zones and Rio Grande do Norte Domain, in the Setentrional Zone. In this way, it cuts some important geologic structures, like the limit of the São Francis Craton and the Borborema Province, Paleozoic and Mesozoic sedimentary basins of Tucano, Jatobá and Potiguar and the extensive Pernambuco and Patos shear zones. Recognition techniques gravity sources in the subsurface, such as spectral analysis and Euler Deconvolution, were applied to the Bouguer anomalies, as well as their regional and residual components. These techniques provided in-formation on possible anomalous bodies, which correlated with pre-existing geological and geophysical data, subsidized a 2.5 D gravity modeling of the lithosphere beneath the Borborema Province and its southern limit with the São Francisco Craton.

Aplicação da modelagem estrutural computacional direta na análise da geometria de falhas: exemplo da falha de Baixa Grande (Bacia Potiguar - NE do Brasil)

The Baixa grande fault is located on the edge of the S-SW Potiguar Rift. It limits the south part of Umbuzeiro Graben and the Apodi Graben. Although a number of studies have associated the complex deformation styles in the hanging wall of the Baixa Grande Fault with geometry and displacement variations, none have applied the modern computational techniques such as geometrical and kinematic validations to address this problem. This work proposes a geometric analysis of the Baixa Fault using seismic interpretation. The interpretation was made on 3D seismic data of the Baixa Grande fault using the software OpendTect (dGB Earth Sciences). It was also used direct structural modeling, such as Analog Direct Modeling know as Folding Vectors and, 2D and 3D Direct Computational Modeling. The Folding Vectors Modeling presented great similarity with the conventional structural seismic interpretations of the Baixa Grande Fault, thus, the conventional interpretation was validated geometrically. The 2D direct computational modeling was made on some sections of the 3D data of the Baixa Grande Fault on software Move (Midland Valley Ltd) using the horizon modeling tool. The modeling confirms the influence of fault geometry on the hanging wall. The Baixa Grande Fault ramp-flat-ramp geometry generates synform on the concave segments of the fault and antiform in the convex segments. On the fault region that does not have segments angle change, the beds are dislocated without deformation, and on the listric faults occur rollover. On the direct 3D computational modeling, structural attributes were obtained as horizons on the hanging wall of the main fault, after the simulation of several levels of deformation along the fault. The occurrence of structures that indicates shortening in this modeling, also indicates that the antiforms on the Baixa Grande Fault were influenced by fault geometry

Estimativa da profundidade do embasamento na bacia potiguar usando inversão gravimétrica

The gravity inversion method is a mathematic process that can be used to estimate the basement relief of a sedimentary basin. However, the inverse problem in potential-field methods has neither a unique nor a stable solution, so additional information (other than gravity measurements) must be supplied by the interpreter to transform this problem into a well-posed one. This dissertation presents the application of a gravity inversion method to estimate the basement relief of the onshore Potiguar Basin. The density contrast between sediments and basament is assumed to be known and constant. The proposed methodology consists of discretizing the sedimentary layer into a grid of rectangular juxtaposed prisms whose thicknesses correspond to the depth to basement which is the parameter to be estimated. To stabilize the inversion I introduce constraints in accordance with the known geologic information. The method minimizes an objective function of the model that requires not only the model to be smooth and close to the seismic-derived model, which is used as a reference model, but also to honor well-log constraints. The latter are introduced through the use of logarithmic barrier terms in the objective function. The inversion process was applied in order to simulate different phases during the exploration development of a basin. The methodology consisted in applying the gravity inversion in distinct scenarios: the first one used only gravity data and a plain reference model; the second scenario was divided in two cases, we incorporated either borehole logs information or seismic model into the process. Finally I incorporated the basement depth generated by seismic interpretation into the inversion as a reference model and imposed depth constraint from boreholes using the primal logarithmic barrier method. As a result, the estimation of the basement relief in every scenario has satisfactorily reproduced the basin framework, and the incorporation of the constraints led to improve depth basement definition. The joint use of surface gravity data, seismic imaging and borehole logging information makes the process more robust and allows an improvement in the estimate, providing a result closer to the actual basement relief. In addition, I would like to remark that the result obtained in the first scenario already has provided a very coherent basement relief when compared to the known basin framework. This is significant information, when comparing the differences in the costs and environment impact related to gravimetric and seismic surveys and also the well drillings

Comparação de desempenho da deconvolução preditiva multicanal e da filtragem f-k na atenuação de múltiplas do fundo do mar

The seismic reflection is used on a large scale in oil exploration. In case of marine acquisition the presence of high impedance contrast at the interfaces water/air generates multiple reflections events. Such multiple events can mask primary events; thus from the interpretational viewpoint it is necessary to mitigate the multiples. In this manuscript we compare two methods of multiple attenuation: the predictive multichannel deconvolution (DPM) and the F-K filtering (FKF). DPM is based in the periodicity of the multiples while FKF is based in multiples and primaries splitting in F-K domain. DPM and FKF were applied in common-offset and CDP gathers, respectively. DPM is quite sensible to the correct identification of the period and size of the filter while FKF is quite sensible to an adequate choice of the velocity in order to split multiples and primaries events in the F-K domain. DPM is a method that is designed to act over a specific event. So, when the parameters are well selected, DPM is very efficient in removing the specified multiple. Then DPM can be optimized by applying it several times, each time with a different parameterization. A deficiency of DPM occurs when a multiple is superposed to a primary event: in this situation, DPM can attenuate also the primary event. On the other hand, FKF presents almost the same performance to all multiples that are localized in the same sector of the F-K domain. The two methods can be combined in order to take advantage of their associated potentials. In this situation, DPM is firstly applied, with a focus in the sea bed multiples. Then FKF is applied in order to attenuate the remaining multiples

Caracterização multi-escalar de bandas de deformação nas tectonossequências paleozóica, pré- e sin-rifte da Bacia do Araripe, Nordeste do Brasil

Deformation bands are structures, developed in porous sandstones, that has small offsets and they are not shown on seismic section. The deformation bands of the pre and synrift sandstones of Araripe Basin were studied in outcrop, macroscopic and microscopic scales. The hierarchical, cinematic and spatial-geometric characteristics, and also the deformational mechanisms acting during its structural evolution were established too. In general, the mesoscopic scale observation allowed to discriminate deformation bands as singles or clusters in three main sets: NNE-SSW dextral; NE-SW normal (sometimes with strike-slip offset); and E-W sinistral; further a bed-parallel deformation bands as a local set. The microscopic characterization allowed to recognize the shearing and cataclastic character of such structures. Through the multi-scale study done in this work we verified that deformation bands analyzed were preferentially developed when sandstones under advanced stage of lithification. We also infer that the geometrical-spatial complexity of these bands, together with the presence of cataclastic matrix, can difficult the migration of fluids in reservoir rocks, resulting on their compartmentalization. Therefore, the study of deformation bands can aid researches about the structural evolution of sedimentary basin, as well as collaborate to understand the hydrodynamic behavior of reservoirs compartmented by these deformational structures

Evidências da herança geotectônica pré-cambriana na geração da barcia potiguar: um estudo geofísico multdisciplinar

The 3D gravity modeling of the Potiguar rift basin consisted of a digital processing of gravity and aeromagnetic data, subsidized by the results of Euler deconvolution of gravity and magnetic data and the interpretation of seismic lines and wells descriptions. The gravity database is a compilation of independent geophysical surveys conducted by several universities, research institutions and governmental agencies. The aeromagnetic data are from the Bacia Potiguar and Plataforma Continental do Nordeste projects, obtained from the Brazilian Petroleum Agency (ANP). The solutions of the Euler Deconvolution allowed the analysis of the behavior of the rift main limits. While the integrated interpretation of seismic lines provided the delimitating horizons of the sedimentary formations and the basement top. The integration of these data allowed a 3D gravity modeling of basement topography, allowing the identification of a series of internal structures of the Potiguar rift, as well intra-basement structures without the gravity effect of the rift. The proposed inversion procedure of the gravity data allowed to identify the main structural features of the Potiguar rift, elongated in the NE-SW direction, and its southern and eastern faulted edges, where the sedimentary infill reachs thicknesses up to 5500 m. The southern boundary is marked by the Apodi and Baixa Grande faults. These faults seem to be a single NW-SE oriented fault with a strong bend to NE-SW direction. In addition, the eastern boundary of the rift is conditioned by the NE-SW trending Carnaubais fault system. It was also observed NW-SE oriented faults, which acted as transfer faults to the extensional efforts during the basin formation. In the central part of the residual anomaly map without the gravity effect of the rift stands out a NW-SE trending gravity high, corresponding to the Orós-Jaguaribe belt lithotypes. We also observe a gravity maximum parallel to the Carnaubais fault system. This anomaly is aligned to the eastern limit of the rift and reflects the contact of different crustal blocks, limited by the eastern ward counterpart of the Portalegre Shear Zone

Modelagem estrutural física de semigrábens ortogonais e oblíquos à distenção regional: influência da trama do embasamento e comparação com analógicos no nordeste brasileiro

The physical structural modeling tool is being increasingly used in geology to provide information about the evolutionary stages (nucleation, growth) and geometry of geological structures at various scales. During the simulations of extensional tectonics, modeling provides a better understanding of fault geometry and evolution of the tectonic-stratigraphic architecture of rift basins. In this study a sandbox type apparatus was used to study the nucleation and development of basins influenced by previous structures within the basement, variably oriented as regards to the main extensional axis. Two types of experiments were conducted in order to: (i) simulate the individual (independent) development of half-grabens oriented orthogonal or oblique to the extension direction; (ii) simulate the simultaneous development of such half-grabens, orthogonal or oblique to the extension direction. In both cases the same materials (sand mixed with gypsum) were used and the same boundary conditions were maintained. The results were compared with a natural analogue represented by the Rio do Peixe Basin (one of the eocretaceous interior basins of Northeast Brazil). The obtained models allowed to observe the development of segmented border faults with listric geometry, often forming relay ramps, and the development of inner basins faults that affect only the basal strata, like the ones observed in the seismic sections of the natural analogue. The results confirm the importance of basement tectonic heritage in the geometry of rift depocenters

Caracterização de reservatórios siliciclásticos neoaptianos: um estudo do membro carmópolis no campo de Camorim, sub-bacia de Sergipe, Brasil

The Camorim Oilfield, discovered in 1970 in the shallow water domain of the Sergipe Sub-basin, produces hydrocarbons from the Carmópolis Member of the Muribeca Formation, the main reservoir interval, interpreted as siliciclastics deposited in an alluvial-fluvial-deltaic context during a late rifting phase of Neoaptian age, in the Sergipe-Alagoas Basin. The structural setting of the field defines different production blocks, being associated to the evolution of the Atalaia High during the rift stage and subsequent reactivations, encompassing NE-SW trending major normal faults and NWEW trending secondary faults. The complexity of this field is related to the strong facies variation due to the interaction between continental and coastal depositional environments, coupled with strata juxtaposition along fault blocks. This study aims to geologically characterize its reservoirs, to provide new insights to well drilling locations in order to increase the recovery factor of the field. Facies analysis based on drill cores and geophysical logs and the 3D interpretation of a seismic volume, provide a high resolution stratigraphic analysis approach to be applied in this geodynamic transitional context between the rift and drift evolutionary stages of the basin. The objective was to define spatial and time relations between production zones and the preferential directions of fluid flow, using isochore maps that represent the external geometry of the deposits and facies distribution maps to characterize the internal heterogeneities of these intervals, identified in a 4th order stratigraphic zoning. This work methodology, integrated in a 3D geological modelling process, will help to optimize well drilling and hydrocarbons production. This methodology may be applied in other reservoirs in tectonic and depositional contexts similar to the one observed at Camorim, for example, the oil fields in the Aracaju High, Sergipe Sub-basin, which together represent the largest volume of oil in place in onshore Brazilian basins

Caracterização geomorfológica e paleogeográfica da plataforma continental adjacente a foz do Rio Apodi-Mossoró, RN/Brasil

The brazilian marginal basins have a huge potential to generate and accumulate petroleum. Incised valleys which are eroded in response to a fall of relative sea level are related to potential reservoir as well, modern drowned-valley estuaries serve as harbors to petroleum and salt industries, fisheries, waste-disposal sites and recreational areas for a significant fraction of the world s population. The combined influence of these factors has produced a dramatic increase in research on modern and ancient incised-valley systems. This research is one expression of this interest. The integrated use of satellites images and high resolution seismic (bathymetry, sides scan sonar) was used on the Apodi River mouth-RN to characterizes the continental shelf This area is located at the Potiguar Basin in the NE Brazilian Equatorial Atlantic margin. Through bathymetric and side scan sonar data processing, a digital Terrain Model was developed, and a detailed geomorphologic analysis was performed. In this way was possible to recognize the geomorphologic framework and differents sismofacies, which may influence this area. A channel extending from the ApodiMossoró river mouth to the shelf edge dominates the investigated area. This structure can be correlated with the former river valley developed during the late Pleistocene sea level fall. This channel has two main directions (NW-SE and NE-SW) probably controlled by the Potiguar Basin structures. The western margin of the channel is relatively steep and pronounced whereas the eastern margin consists only of a gentle slope. Longitudinal bedforms and massive ridges also occur. The first are formed doe to the shelf sediment rework and the reef-like structures probably are relics of submerged beachrock-lines indicating past shoreline positions during the deglacial sea-level rise. The sub-bottom seismic data allow the identification of different sismic patterns and a marcant discontinuity, interpreted as the Upper

analise da dispersao de ondas de superficie na provincia borborema, Nordeste do Brasil

The Borborema Province, Northeastern Brazil, had its internal structure investigated by different geophysical methods like gravity, magnetics and seismics. Additionally, many geological studies were also carried out to define the structural domains of this province. Despite the plethora of studies, there are still many important open aspects about its evolution. Here, we study the velocity structure of S-wave in the crust using dispersion of surface waves. The dispersion of surface waves allows an estimate of the average thickness of the crust across the region between the stations. The inversion of the velocity structure was carried out using the inter-station dispersion of surface waves of Rayleigh and Love types. The teleseismic events are mainly from the edges of the South and North American plates. The period of data collection occurred between 2007 and 2010 and we selected 7 events with magnitude above 5.0 MW and up to 40 km depth. The difference between the events back-azimuths and the interstation path was not greater than 10. We also know the depth of the Moho, results from Receiver Functions (Novo Barbosa, 2008), and use those as constrains in inversion. Even using different parameterizations of models for the inversion, our results were very similar the mean profiles velocity structure of S-wave. In pairs of stations located in the Cear´a Central Domain Borborema the province, there are ranges of depths for which the velocities of S are very close. Most of the results in the profile near the Moho complicate their interpretation at that depth, coinciding with the geology of the region, where there are many shear zones. In particular, the profile that have the route Potiguar Bacia in inter-station, had low velocities in the crust. We combine these results to the results of gravimetry and magnetometry (Oliveira, 2008) and receptor function (Novo Barbosa, 2008). We finally, the first results on the behavior of the velocity structure of S-wave with depth in the Province Borborema

Relationship between DNA damage and sperm head birefringence

Birefringence or double refraction is the decomposition of a ray of light into two rays when it passes through an anisotropic material such as quartz. Sperm cells have been demonstrated to be optically anisotropic. The objective of this study was to evaluate the relationship between the pattern of human sperm head birefringence (SHBF) and DNA damage. A total of 26 patients with normal semen were included. DNA damage (fragmentation and denaturation) was evaluated in the sperm head in the context of birefringence, both total (SHBF-T) and partial (SHBF-P), by terminal deoxyribonucleotidyl transferase (TdT)-mediated dUDP nick-end labelling assay and acridine orange fluorescence, respectively. Positive DNA fragmentation in spermatozoa with SHBF-T (205/1053; 19.5%) was significantly higher (P < 0.0001) than in spermatozoa that presented SHBF-P (60/820; 7.3%). However, the percentage of denatured DNA in spermatozoa with SHBF-T (824/1256; 65.6%) was not significantly different from the ones with SHBF-P (666/1009; 66.0%). In conclusion, the data support a positive relationship between spermatozoa with total SHBF in their head and increased DNA fragmentation. (C) 2011, Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

Prevalence of Refractive Errors in a Brazilian Population: The Botucatu Eye Study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fator de correção para indivíduos com capacidade acomodativa baseado no uso do refrator automático

OBJETIVO: Pesquisar um fator de correção para avaliação do erro refrativo sem a utilização da cicloplegia. MÉTODOS: Foram estudados 623 pacientes (1.246 olhos), de ambos os sexos, com idade entre 3 e 40 anos. As refratometrias estática e dinâmica foram obtidas usando-se o refrator automático Shin-Nippon Accuref-K 9001. A cicloplegia foi obtida com a instilação de uma gota de colírio ciclopentolato a 1%, com refratometria estática 30 minutos após. Os dados foram submetidos à análise estatística usando a técnica do modelo de regressão linear e modelo de regressão múltipla do valor dióptrico com e sem cicloplegia, em função da idade. RESULTADOS: A correlação entre valores dióptricos sem e com cicloplegia quanto ao erro astigmático variou de 81,52% a 92,27%. Quanto ao valor dióptrico esférico, a correlação foi menor (53,57% a 87,78%). O mesmo se observou em relação ao eixo do astigmatismo (28,86% a 58,80%). O modelo de regressão múltipla em função da idade mostrou coeficiente de determinação múltiplo maior para a miopia (86,38%) e astigmatismo (79,79%). O menor coeficiente foi observado para o eixo do astigmatismo (17,70%). CONCLUSÃO: Avaliando-se os erros refrativos com e sem cicloplegia, observou-se alta correlação nas ametropias cilíndricas. Foram desenvolvidas equações matemáticas como fator de correção para refratometrias dos pacientes sem cicloplegia, portadores de ametropias cilíndricas e esféricas.