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Os dados sismicos terrestres, geralmente, apresentam baixa razao sinal-ruido devido, entre outros fatores, a presenca de ground roll, um ruido caracterizado por eventos coerentes e lineares, com altas amplitudes, baixas frequencias temporais e baixas velocidades e, na maioria dos casos, dispersivos, que se sobrepoem as reflexoes, prejudicando o processamento e a interpretacao dos dados. Quando a tentativa de atenuar o ground roll durante a aquisicao dos dados (utilizando arranjos de fontes e receptores) falha, diversos metodos podem ser empregados no processamento. Neste trabalho, discute-se um metodo de filtragem baseado no filtrode forma de Wiener, sua implementacao e seus principais parâmetros. Tambem e apresentada uma variante do metodo, baseada no algoritmo de deconvolucao direta. Os resultados da aplicacao da filtragem direta em dados sismicos reais sao bastante satisfatorios, quando comparados com aqueles obtidos com os metodos convencionais FK e corta-baixas. ABSTRACT: Onshore seismic data often have low signal to noise ratio due to, among other factors, the presence of ground-roll, a noise characterized by coherent, linear and dispersive events with high amplitudes, low frequencies and velocities. This noise overlaps with reflections, hindering the data processing and interpretation. When the attempts to reduce the ground-roll during data acquisition (using source and receiver arrays) fail, several methods can be used in seismic processing. Here we discuss a filtering method based on Wiener shaping filter, its implementation and its main parameters. We also present a different approach based on the direct deconvolution algorithm. The results of the application of direct methods to a real seismic data set are quite satisfactory when compared with those obtained with conventional FK and low-cut filters. Keywords: ground roll, shaping filters, seismic data processing.

GROUND ROLL ATTENUATION USING SHAPING FILTERS AND BAND LIMITED SWEEP SIGNALS