Estimation Of Formation Parameters Using Full Waveform Acoustic and Shear Wave Logs

Abstract

A combination of borehole Stoneley waves from full waveform acoustic logs and direct shear wave logs was used to estimate formation permeability and shear wave velocity. Data sets used here were collected by Area's array full waveform acoustic logging tool and shear wave logging tool. The P- and S-wave velocities of the formation are determined by threshold detection with cross-correlation correction from the full waveform and the shear wave log, respectively. The full waveform acoustic logging data are also processed using the Extended Prony's method to estimate the borehole Stoneley wave phase velocity and attenuation as a function of frequency. Two different borehole models are considered for the inversion of Stoneley wave velocity and attenuation data. They are the isotropic elastic and the porous isotropic borehole models. Inversion parameters include shear wave velocity and formation permeability. Inverted shear wave velocities and permeabilities are compared with the shear wave log and the core permeability measurements, respectively, for an integrated interpretation and possible identification of shear wave anisotropy.