The Full Waveform Acoustic Log Inversion Problem

Abstract

This paper presents the full waveform acoustic log inversion problem for a multisource - multireceiver tool logging a cylindrical fluid-filled borehole. The problem is formulated in the frequency-depth domain. A priori knowledge about the source array spectra and the borehole formation parameters (velocity, attenuation, density) is taken Into account. It is shown that the inversion problem can be formulated as a Separable Nonlinear Least Squares (SNLS) problem with separable nonlinear equality constraints. The case where the source is known and parameterized is studied with synthetic data and an inversion for V[subscript p], V[subscript s], V[subscript f] and P[subscript b] is implemented and studied.