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3rd Latin American Geosciences Student Conference
- Conference date: July 27 - August 1, 2015
- Location: Niterói, Brazil
- Published: 27 July 2015
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Analysis of Lithologic Correlation of Conventional Well Log Data from Namorado Field, Campos Basin, Brazil
Authors C.O. De Souza and A.M.V. CarrascoSummaryComputer support is a basic tool in the well logging correlation for both engineers and geologists by reduc-ing the time and effort when exists a lot of information in order to analysis and correlation of areas of interest ( Startzman, 1987 ). The analysis of geophysical well logging in the oil industry is a resource that helps experts in Petroleum Engineering, in areas such as Reservoir Engineering and Petrophysics. The success of this anal-ysis depends on the interpreter's ability to visualize and identify the similarity among the responses of well logs in a section of interest. This work is usually not quantita-tive and requires knowledge of the area to be studied and reasoning.
The data log used in this work correspond to Namorado field in the Campos Basin (Brazil). With this data you can obtain lithology information of the region using the strat-igraphic chart available and make possible to make a two-dimensional correlation between the selected wells (well-to-well). These activities were carried out using the Interactive Petrophysics (IP) software version 4.2, spe-cialized in the petrophysics issue.
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Paleodrainage Mapping of the São Paulo Southern Continental Shelf on the Santos Basin
More LessSummaryThe occurrence of a paleodrainage was mapped in the continental shelf of São Paulo through previous studies by using bathymetric and sedimentological data. More recently, with the use of high resolution and low penetration seismic was possible the identification of its recent paleogeographic characteristic. With the aim to know the geometry and sismo-stratigraphic characteristics of the region, cruises mapped southward paleochannels of the inner continental shelf of São Paulo. The equipment used in data collection was the Sub Bottom Profiler 3.5 KHz. Furthermore, in the processing of seismic records was used SonarWiz 5.0, where internal reflectors were determined in sedimentary package. The data collected led to the identification of seismic stratigraphic, high concentration of paleochannels and a gas curtain in the seismic registers. The localization of the paleochannels mapped was concentrated in the central portion of the seismic lines, in front of the river outfall. These results strongly suggest a pattern of extension of current alluvial courses to the outer regions of the platform, dug in regressive periods. The data of this study should be considered preliminary for new surveys, aiming for a more precise characterization of the subject.
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Comparative Heavy Mineral Composition of Alluvial Fans in the Resende Basin, Southeast Brazil - Preliminary Results
Authors G.P. de Souza, C.M. Valeriano, R.R.C. Ramos and L.E.A. BarbosaSummaryThe aim of the work is characterize and compare the heavy mineral composition of Alkaline and Basement-derived alluvial fans of the Paleogene of the Resende Basin. The methodology was based in field works to collect samples of the two main sedimentary sorces of the region: the Itatiaia alkaline Massif and the faulted north edge of the Resende basin. The samples were processed in laboratory to concentrate the heavy minerals and then, the assemblage was analyzed in binocular loupe. The two samples showed differences principally in zircon forms, bipiramidals and short prisms in alkaline sample and long prisms in basement sample. Compositional differences also has been noticed, the presence of biotite and anatase only in the alkaline-derived alluvial fan sample, while in basement-derived ocurred garnet and tourmaline. The differences of the two assemblages can be used as markers of the alkaline alluvial fans contribution principally for the fluvial systems of the Resende Formation.
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Frequency-domain Modeling Using Implicit and Explicit Finite-difference Operators
Authors D. Revelo and R. PestanaSummarySeveral techniques have been developed to modeling the wave equation. In this paper we introduce the frequency-domain finite-difference (FDFD) modeling and its implementation using the explicit (2nd and 4th) and implicit (nine-point) centered difference operators for solving the scalar Helmholtz equation. We discuss some proprieties of the resulting linear system after the discretization of the wave equation and show that our implemented nine-point implicit scheme produces a much more accurate result in comparison with the 2nd and 4th schemes for seismic wave simulations in the frequency domain.
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The Separation of Multipath Angle Domain Common Image Gathers for Complex Structures
Authors X.Z. Zhang, M.O. Ostadhassan, A.U.B. Buriti and A. Guedes BarrosSummaryImaging complex subsuface targets, for example subalt sediments and salt flanks becomes more and more challenging in seismic exploration. When the cross-correlation image condition is used in reverse time migration for each source, the contributions are summed across all the time steps to give one migrated image. The stacked image includes contributions from all primary and prismatic waves, or even artifacts. Thus the final image summation contains a variety of wavefield distortions. Nevertheless, if the image time for each multipath arrival is saved during wavefield extrapolation, and apply image condition at their image times for multipath contributions, we can obtain the multipath partial images. The separate partial images can by displayed for the primary contributions, or any combination of different types of waves (with or without artifacts). The synthetic data from the Sigsbee2 model shows that the relative contributions of multipath arrivals to subsalt images are different.
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Application of the Generalized Simulated Annealing Algorithm to the Solution of 2D Gravity Inversion of Basement Relief
Authors O.F. Mojica and A. BassreiSummaryGeneralized simulated annealing (GSA) is an optimization technique for locating the global optimum, which contains both classical simulated annealing (SA) and fast simulated annealing (FSA) as particular cases. In this paper, GSA was applied to invert gravity data to obtain the geometry of the 2D basement relief. The behaviour of the algorithm and its comparison with the modified particle swarm optimization (PSO) algorithm were studied by simulations with synthetic data. The results obtained from the inversion show that both GSA and PSO inversion schemes give similar results. However, calibrating the GSA algoritm could lead to better results.
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Modeling of Attenuation and Dispersion of Elastic Waves in Saturated Porous Media
Authors O.F. Pinto, A. Duitama and L. MontesSummaryOil and gas exploration, Biot Theory, and numerical simulation have allowed the development of modeling of elastic wave propagation in environments similar to those found in the exploration of reservoirs, where the Biot Theory can be solved by the finite difference methods. In this paper was modeled the propagation of a plane wave through three models with different porosities of 5%, 10% and 15%, saturated with water. From the modeling, three seismograms were achieved in time, then were analyzed spectrally. Afterwards, the quality factor as a function of frequency and porosity was calculated, also compressional wave velocity as a function of porosity was calculated. Finally it was concluded that the attenuation, dispersion and travel time of seismic waves increases with the porosity and the wave velocity, dominant frequency and quality factor decrease with porosity.
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Magnetic Methods Applied to Map Volcanic Rocks, Magnetic Lineaments and Domain in Araguaia Belt and Parnaiba Basin
Authors L. da S. R. Mocitaiba, D.L. de Castro, A.C. Tavares, J.G. Damaceno and I.L.G. GalvãoSummaryThe study area includes the eastern portion of the Neoproterozoic Araguaia Fold Belt and the western edge of the Paleozoic Parnaíba Basin in N Brazil. The Araguaia Belt comprises an extensive sequence of metasedimentary and igneous rocks. Intrusive and extrusive igneous rocks (dykes and sills) occur within the sedimentary sequences of Parnaíba Basin. Then, this paper presents a geophysical study to map the huge magmatic manifestations which occur in western border of the Parnaiba basin (Mosquito Formation), volcanic rocks in the eastern border of Araguaia Belt and magnetic lineaments and domain in those areas, based on airborne magnetic data.
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Two Dimension Seismic Modeling and an Understanding of Wave Propagation trough a Viscoelastic Media
Authors J.Y. Dechiche, D. Freitas and M. CetaleSummaryIn order to produce synthetic seismograms from acoustic, pure elastic, and viscoelastic seismic modelling and conduct a comparison among the different datasets, we have used an open 3D finite-difference seismic modeling package produced by Karlsruhe Institute of Technology (KIT) named SOFI3D.
SOFI3D code was built in order to take advantage of maximum computational efficiency, being implemented for parallel environment based message passing interface or MPI.
A cluster of 27 processing units (based on Geology and Geophysics Dept. of Universidade Federal Fluminense) and high speed network are the hardware used to produce the results which are presented and discussed in in this work.
Eight different shot gather synthetic seismograms were produced using the same earth model. Thus a roll/flip comparison is done in order to understand what happens on the wave field reflection at each model configuration.
Significant differences in attenuation effects have been obseved between elastic and viscoelasitc modelign results. Several kinds of geological configurations are quite dispersive and there is an effect in signal to noise ratio, especially when dealing with unconsolidated sediments of shallower ocean bottom and dealing with heavy oil reservoir sandstones.
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