2019-08-302019-08-302011NUNES, Cristiano Ícaro Rego. Utilização de reflexões múltiplas no imageamento sísmico: análise de metodologias. Orientadora: Ellen de Nazaré Souza Gomes. 2011. 143 f. Trabalho de Curso (Bacharelado em Geofísica) - Faculdade de Geofísica, Instituto de Geociências, Universidade Federal do Pará, Belém, 2011. Disponível em: http://bdm.ufpa.br/jspui/handle/prefix/1830. Acesso em:.http://bdm.ufpa.br/jspui/handle/prefix/1830Conventional seismic processing treats multiple reflections as noise, removing them from the imaging process. However, multiples are generated by subsurface reflectors, and therefore contain structural information about them. In this context, some works have been developed in order to use multiple reflections as signal. This work is a theoretical overview about the most relevant works which make use of free surface-related multiples in seismic imaging. Three approaches are shown: in the first one, where multiples are directly used in the imaging process, it is shown the Kirchhoff migration, crosscorrelation migration, shot-profile migration and reverse-time migration with multiples; in the second approach, it is shown the transformation of multiple reflections into pseudoprimaries, which are after migrated by shot-profile migration and by source-receiver migration; in the third approach, primary and multiple reflections are jointly used in the imaging process. The theoretical principles, obtained results, practical aspects, advantages and disadvantages of each methodology are discussed. Important applications are shown, such as a much broader illumination of the subsurface and the recovery of missing large and near offsets, related to acquisition gaps. Some of the methodologies presented need multiples and primaries to be previously separated, and generate noisier images compared to those generated by primaries only. However, some practical solutions that help solve these problems are shown. As the migration of multiples means using the recorded data as a source wavefield, crosscorrelation may not be a good approximation. Therefore, it is recommended to use deconvolution as the imaging condition, which provides better amplitude balancing, higher signal-to-noise ratio and improved vertical resolution. In general, the “state of art” of the utilization of multiple reflections as signal is in its consolidation stage, but it is already proved that multiples can provide structural information that primaries, alone, are not capable of providing, which helps to create high-quality images of the subsurface.Acesso AbertoProspecção SísmicaProcessamentoImageamentoReflexões MúltiplasCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOFISICA::SISMOLOGIATrabalho de Curso - Graduação - Monografia