Verificação experimental do modelo efetivo de Hudson-Crampin para meios anisotrópicos fissurados cujo o meio de fundo apresenta isotropia transversal

Abstract

The physical modeling of cracked media, using scaled laboratory experiments, has been used as an alternative for understanding the effect of anisotropy on the characterization of the cracked hydrocarbon reservoir. The main objective of this work was to verify experimentally the predictions of Hudson-Crampin’s effective model to cracked media. For this purpose, ultrasonic and petrophysical measurements were performed on sixteen synthetic anisotropic samples with different crack densities distributed in four groups with distincts aspect ratios (0.08, 0.20, 0.32 and 0.52). Beside theses, one sample no cracks and weak VTI ansisotropy were used as reference sample. The cracks were simulated by void spaces in the form of discs in an matrix (made with sand and cement). Related to the estimatives of velocity performed by the theoretical models, Hudson-Crampin’s model presents a better adjustment for VP and VS propagating perpendicular to the plane of cracks for the dry and saturated conditions. These estimatives became more evident in the case where the crack density and aspect ratios are low. In addition to the velocity values, our comparison was also performed in terms of Thomsen’s parameters ε, γ and δ.