Abstract：Anisotropy in crustal rocks may be due to fractures, unequal stresses, grain orientation, or fine layering. Finely laminated rocks can be represented as transversely isotropic solids, with an axis of symmetry perpendicular to the layers. Waves radiated from a point force in such a medium were computed by numerical inversion of double fourier transforms of displacements, expressed in terms of displacement potentials. For severely anisotropic rocks, the quasishear waves exhibit complex directionality, with cusps. The quasi compressional wave departs less drastically from the directivity in an isotropic solid. Arrival times for both waves agree with group velocities computed by means of expr ssions from the literature. The same general method was used to compute the response of an acoustic logging tool in a fluid-filled borehole lying along the symmetry axis of the solid. The waveforms show promise of indicating the degree of anisotropy of the solid. For shear-wave reflection profiling, one possible effect of anisotropy was illustrated ay means of simple synthetic seismograms. One layer with anisotropy in the horizontal plane will split the shear wave into two pulses, thus complicating deeper reflections. The plane of polarization of the two reflection from the layer itself will be rotated. Thus, comparison of shear-wave profiles with different directions of excitation should indicate any subsurface anisotropy in the horizontal plane.
引用本文:
J. E. White, 俞寿朋. 横向各向同性介质中的地震波[J]. 石油地球物理勘探, 1982, 17(1): 26-32.
J. E. White. Seismic waves in transversely isotropic media. OGP, 1982, 17(1): 26-32.
