Synthetic data inversion of porous ocean sediment based on Biot model

Abstract

Geoacoustic inversion usually estimates parameters by modeling the ocean sediment as either acoustic or elastic media. Treating the sediment as porous medium and partial inversion for sediment moduli has been performed [N.P. Chotiros, J. Acoust. Soc. Am. 112, 1853–1868 (2002)]. In this study, synthetic data inversion based on the full Biot model consisting of 13 unknown parameters is performed. At first, sensitivity tests are done to figure out how much a parameter affects the acoustic fields. Then, iterative inversions using synthetic data are performed based on the parameter’s sensitivities. Sensitive parameters are searched first, while other insensitive ones are fixed at their representative values. Finally, the insensitive parameters are optimized with the previous found sensitive parameter values fixed. In addition to the full Biot model, the equivalent fluid model utilizing complex wave speed and density is used for the inversion to test if the Biot parameters can be retrieved from these inverted complex wave speed and density.