Atenuação elástica das rochas da bacia do rio do Peixe.

Abstract

In this work petrophysical and elastic properties of rocks from the rio do Peixe Basin - Brazil - were obtained and analyzed throught laboratory and computacional assays, providing information about grain density, porosity, permeability, velocity and attenuation attributes from elastic waves. Correlations were established between the viscoelastic behavior and the facies units. Moreover, two different methods to determine the quality factor Q (which corresponds to a quantitative description of complex process associated to wave attenuation) in the frequency domain were compared: the spectral ratio and the frequency shift methods. The analysis show good correlacion of the elastic velocities with porosity and, also, with the density, which results from carbonatic cementation, extensively present in the Basin. The quality factors does not correlate strongly with other measured properties. Those are more affected by tectonic structures. In general, a particular viscoelastic, behavior is observed, witch is atributted to the diagenetic and structural complexity of the Basin.