MIGRAÇÃO REVERSA NO TEMPO UTILIZANDO OPERADORES PSEUDO-ACÚSTICOS EM MEIOS TRANSVERSALMENTE ISOTRÓPICOS

Abstract

Abstract of the Dissertation presented to the National Observatory’s Graduate Program in Geophysics as a partial fulfillment of the requirements for the degree of Master in Geophysics. Reverse-Time Migration using pseudoacoustic operators in Transverse Isotropic Media Razec Cezar Sampaio Pinto da Silva Torres March/2020 Reverse-time migration (RTM) has great advantages over other seismic imaging techniques, especially when the geological environment presents high complexity. This, for example, is the case for petroleum systems composed and influenced by the salt dynamics. Such targets are difficult to be migrated by conventional methods, especially those that use approximations of the ray tracing to describe the physi- cal behavior of the wave. In this context, the pre-stack RTM migration produces a higher quality seismic image. The main advantages of RTM are: It correctly handles the multi-arrivals of the wave, It has no dip limitation about the reflector position, enables imaging of overturned waves and some forms of multiples (prismatics re- flections). These advantages are possible because RTM uses a full wave equation to model wave propagation. Thus, this project aims the implementation and de- velopment of the pre-stack RTM technique for tilted transverse isotropic media, in which it contains rotation symmetry oriented by a tilted symmetry axis. In addition, this project investigated the influence of TTI anisotropy on seismic imaging via the application of RTM migration in isotropic and anisotropic media, in order to en- hance the main differences in the images. For this, four case studies were prepared, namely: homogeneous model, calha model, anticlinal model and benchmark BP TTI 2007 model. Through these experiments it was noted that isotropic algorithms are not enough to produce reliable results in anisotropic media. Therefore, considering seismic anisotropy is extremely important for seismic imaging because it avoids er- rors in positioning the reflectors and distortions produced when we disregard the anisotropy, therefore generating more interpretable seismic images. Keywords: Reverse-Time Migration; Anisotropy; TTI.