  Full-waveform inversion (FWI) is a technique having the potential for
building high-resolution elastic velocity models. We proposed to apply this
technique to wireline monopole acoustic logging data to obtain the near
wellbore formation velocity structures, which can be used in wellbore damage or
fluid intrusion evaluation. A 2D FWI using monopole acoustic logging data is
presented. The FWI is established in cylindrical coordinates instead of
Cartesian coordinates in order to adapt to the borehole geometry. A
preconditioner is designed for suppressing the influence of the strong borehole
guided waves in the inversion. Synthetic tests demonstrate that high-resoultion
elastic velocity profile around borehole can be inverted from monopole acoustic
logging data by using the proposed method.
