Study of seasonal variation of the P-wave velocity and porosity estimation using seismic refraction
Marcelo Peres RochaWelitom Rodrigues BorgesEduardo Xavier SeimetzPaulo Araújo de AzevedoMárcio Maciel CavalcantiPedro Nogueira
0
Citation
5
Reference
10
Related Paper
Abstract:
PreviousNext No Access12th International Congress of the Brazilian Geophysical Society & EXPOGEF, Rio de Janeiro, Brazil, 15–18 August 2011Study of seasonal variation of the P-wave velocity and porosity estimation using seismic refractionAuthors: Marcelo Peres RochaWelitom Rodrigues BorgesEduardo Xavier SeimetzPaulo Araujo de AzevedoMarcio Maciel CavalcantiPedro Vencovsky NogueiraMarcelo Peres RochaProfessor of the Geosciences Institute of the UnB;, Welitom Rodrigues BorgesProfessor of the Geosciences Institute of the UnB;, Eduardo Xavier SeimetzMaster student of the Applied Geosciences Graduate Program of the IG/UnB;, Paulo Araujo de AzevedoMaster student of the Applied Geosciences Graduate Program of the IG/UnB;, Marcio Maciel CavalcantiMaster student of the Applied Geosciences Graduate Program of the IG/UnB;, and Pedro Vencovsky NogueiraUndergraduate student of the Geology of the IG/UnBhttps://doi.org/10.1190/sbgf2011-164 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract This work shows results of seismic refraction in an area within the University of Brasilia, Campus Darcy Ribeiro, during dry and rainy seasons in the years 2010 and 2011. The main objective was to show the variability of seismic velocity with respect to seasonality, related with the water content in the ground. The results showed seasonal changes in the velocity of the first and second layer of the studied profile. With these results it was possible to estimate the porosity of the first layer. Keywords: interpretation, seismic, refraction, velocityPermalink: https://doi.org/10.1190/sbgf2011-164FiguresReferencesRelatedDetails 12th International Congress of the Brazilian Geophysical Society & EXPOGEF, Rio de Janeiro, Brazil, 15–18 August 2011ISSN (online):2159-6832Copyright: 2011 Pages: 2223 publication data© 2011 Published in electronic format with permission by the Brazilian Geophysical SocietyPublisher:Society of Exploration Geophysicists HistoryPublished Online: 13 Mar 2014 CITATION INFORMATION Marcelo Peres Rocha, Welitom Rodrigues Borges, Eduardo Xavier Seimetz, Paulo Araujo de Azevedo, Marcio Maciel Cavalcanti, and Pedro Vencovsky Nogueira, (2011), "Study of seasonal variation of the P-wave velocity and porosity estimation using seismic refraction," SEG Global Meeting Abstracts : 797-800. https://doi.org/10.1190/sbgf2011-164 Plain-Language Summary KeywordsinterpretationseismicrefractionvelocityPDF DownloadLoading ...Keywords:
Variation (astronomy)
Seismic refraction
Shallow seismic reflection method is a commonly used technique in urban active fault detection,however,special geotectonic environment may sometimes make reflection survey inapplicable.In such cases,high-resolution seismic refraction could be a feasible option.In this study,we use the finite difference method as the main technique and the conventional methods of refraction data interpretation as auxiliary means in the interpretation of high-resolution shallow refraction data for active fault detection in Lanzhou area.After a comprehensive analysis of first-break refraction travel-time characteristics,the velocity structure and interface structure along each profile have been obtained.A detailed description of the detection results from SS04-1 and SS11-2 seismic profiles is presented in this paper.The main stratigraphic interfaces and tectonic features identified by the two profiles are quite consistent with the results from drilling surveys along the profiles.Our results indicate that high-resolution seismic refraction is an effective replacement in areas where reflection seismic survey is hard to carry out.
Seismic refraction
Reflection
Seismic survey
Synthetic seismogram
Vertical seismic profile
Cite
Citations (2)
The refraction method of seismic exploration was initiated in 1952 in the Northern Sahara after several difficulties were encountered with the reflection method. The first tests showed the existence of a deeper marker bed having a velocity of about 6,000 m/sec (20,000 ft/sec) which later proved to be the eroded surface of the basement. Now refraction can be employed, at least in certain regions, in detailed surveys although many difficulties in interpretation still exist. Both field practices and methods of interpretation are discussed.
Seismic refraction
Prospecting
Reflection
Basement
Cite
Citations (13)
The theory and practice of using the refraction seismograph for shallow, subsurface investigations is summarized. This is 1ntended to be a guide to the application of the technique and not a comprehensive analysis of every aspect of the method. The fundamentals are presented and their use in time-intercept calculations and interpretations using delay times are discussed. The limitations of this exploration tool are discussed, and other applications of the equipment, such as uphole surveys, are described. Field procedures for carrying out refraction surveys are also recommended. (auth)
Seismometer
Seismic refraction
Seismic exploration
Cite
Citations (114)
The historical Christus church in Schwelm, Western Germany, shows structural damages at its front side and its southern tower, which are supposed to be due to the geological situation in the area. To describe the shallow underground below the church and to detect locations of anomalies, a refraction seismic program which uses the complete information of the refracted waves consisting of the travel times as well as the phase and amplitude characteristics in the recorded seismic data, was performed. At first a joint application of Common Midpoint- (CMP-) refraction seismics, which uses first break phases and the GRM was applied. In a second step the resulting intercept time sections were depth converted using the results of the GRM and the refraction tomography, which was performed as well. With the combination of These 3 different refraction seismic processing techniques anomalous zones below the church were detected and classified. These anomalies were due to weak zones and karstified cavities in the limestone below the church, as well as to anthropogenic structures. The anomalous zones were located horizontally and vertically, interpreted and thus, together with the results of refraction seismic, a model of the shallow underground below the church was developed.
Seismic refraction
Cite
Citations (0)
Subsurface structure can be mapped using refraction information from marine multichannel seismic data. The method uses velocities and thicknesses of shallow sedimentary rock layers computed from refraction first arrivals recorded along the streamer. A two‐step exploration scheme is described which can be set up on a personal computer and used routinely in any office. It is straightforward and requires only a basic understanding of refraction principles. Two case histories from offshore Peru exploration demonstrate the scheme. The basic scheme is: step (1) shallow sedimentary rock velocities are computed and mapped over an area. Step (2) structure is interpreted from the contoured velocity patterns. Structural highs, for instance, exhibit relatively high velocities, “retained” by buried, compacted, sedimentary rocks that are uplifted to the near‐surface. This method requires that subsurface structure be relatively shallow because the refracted waves probe to depths of one hundred to over one thousand meters, depending upon the seismic energy source, streamer length, and the subsurface velocity distribution. With this one requirement met, we used the refraction method over a wide range of sedimentary rock velocities, water depths, and seismic survey types. The method is particularly valuable because it works well in areas with poor seismic reflection data.
Seismic refraction
Reflection
Vertical seismic profile
Cite
Citations (3)
Seismic velocity determinations in shallow layers (less than 2000 ft deep) have been made recently at an experimental location on the Atlantic Coast. Two reversed refraction profiles were obtained offshore. An unreversed refraction profile was completed on the beach. Reflection profiles were obtained both on the barrier beach and in the adjoining lagoon. Speed layering indicated by seismic reflection and refraction is compared with borehole velocity measurements. Significant thin high-speed and low-speed layers are shown by the borehole velocity data but not by the seismic profile data. The calculations from reflection and refraction shooting show reasonable agreement with the results of the borehole velocity survey for thick layering.
Seismic refraction
Reflection
Layering
Seismic velocity
Vertical seismic profile
Cite
Citations (3)