Study of Seismic P Wave in Mesoscale Fracture-Induced Arbitrary Anisotropic Media

Mesoscale fracture controls the permeability of shale reservoirs, it is one of the main research objectives of natural fractures. The length of the mesoscale fracture is less than 1/4 of the seismic eigen wavelength and greater than 1% of the seismic eigen wavelength, they cannot be identified in actual seismic data and are usually displayed by the azimuthal anisotropy of seismic attributes. In this paper, we propose a calculation process from fracture properties to seismic P-wave velocity and traveltime in anisotropic media induced by multiple sets of arbitrary occurring mesoscale fractures. Based on this process, the variations of the media’s Anisotropic (A-) parameters with fracture properties are studied. Furthermore, variation of P-wave NMO elliptical principle axis with the relative fracture density is studied according to the arbitrary anisotropic theory based on A-parameters.