Inversão de tempos de trânsito de reflexão de GPR: aplicação em arenitos da Bacia Rio do Peixe

Abstract

The primary objective of this Undergraduate Report in Geophysics was to evaluate a 1,5D velocity model through travel-time inversion in a GPR section. The analyzed section, measuring 16 meters in width and 150 ns in double time, was interpreted with three horizontal reflectors and served as the basis for constructing and inverting four models of three layers over a half-space, using different numbers of columns (2, 4, 8, and 16). The methodology employed least squares minimization, with L-curve analysis allowing for the selection of the appropriate Lagrange multiplier, ensuring the smoothness of the obtained solutions. The results showed coherence between the 1D and 1.5D solutions, controlled by a horizontal smoothness constraint that limited the lateral variation of velocities. However, texture variations and the presence of an oblique reflector in the second layer suggested granulometric changes or possible water presence in one of the layers, directly influencing the velocity results. For a more comprehensive interpretation, further development of the inversion method, sample collection at different depths, and integration with other geophysical methods are recommended. This study contributed to the improvement of the velocity inversion methodology in GPR sections and highlighted the importance of an integrated approach in geophysical analysis, broadening the understanding of lithological variations and their implications in geophysical models.