- journal_title：Geophysics
- Contributor：Hsui-lin Liu ; Michael Prange ; Francois Daube
- Publisher：Society of Exploration Geophysicists
- Date：1997-
- Format：text/html
- Language：en
- Identifier：10.1190/1.1444228
- journal_abbrev：Geophysics
- issn：0016-8033
- volume：62
- issue：4
- firstpage：1270
- section：Articles
Formation bedding can cause complex wave propagation in a borehole and introduce velocity bias in sonic logs. Because of the lack of symmetry, little is known about sonic wavefields propagating through a dipping bed. In this paper, we investigate effects on the sonic dipole and monopole wavefields across a dipping interface using a 3-D finite-difference method. For dipole wavefields propagating from a soft to a hard formation across a dipping interface, the transmission is reduced greatly when compared with a horizontal interface. The different transmissions of SV- and SH-waves through the dipping interface result in significant azimuthal amplitude variation and generate large cross-coupled components. This apparent anisotropy should be taken into account when estimating formation shear anisotropy in a dipping formation. For monopole wavefields, the azimuthal averaging caused by a dipping interface reduces the reflection across an interface. This may affect fracture evaluation using the Stoneley reflection coefficient in a dipping formation.