Effects of pore structure and fractures on velocity anisotropy and permeability anisotropy in Ellenburger carbonate, Central Texas

The effects of pore structure and fractures on seismic velocity anisotropy and permeability anisotropy in dry core samples from Ellenburger carbonate, Central Texas are investigated using P-wave velocity (Vp), polarized orthogonal S-wave velocities (Vs1 and Vs2), and permeability (Kh and K v) parallel and perpendicular to the dominant fracture direction. The presence of cracks influences the seismic, elastic and anisotropic parameters under applied stress. The stronger relationship between seismic, petrophysical and petrographic properties parallel than perpendicular to the dominant fracture is because the rock appears to be homogenous parallel to the aligned cracks. The strong correlation of P-wave anisotropy (0.87) and maximum shear anisotropy (0.52) with permeability anisotropy is because of the preferred orientation caused by the fractures. The empirical relationships may be useful in reservoir characterization, mapping fractures and hydraulic fracturing.