Weak-anisotropy moveout approximations for P waves in homogeneous TOR layers

Veronique Farra & Ivan Psencik


We have developed approximate P-wave reflection moveout formulas for a homogeneous layer of orthorhombic symmetry overlying a horizontal or dipping reflector. The symmetry planes of the orthorhombic medium in the layer can be arbitrarily oriented. The formulas are based on the weak-anisotropy approximation. Thus their accuracy depends not only on the strength of anisotropy, but also on deviations of the phase and ray velocities. Nevertheless, the performed tests indicate that for P-wave anisotropy of about 25%, the maximum relative traveltime errors of the formulas do not exceed 3%. The formulas are expressed in terms of six P-wave weak-anisotropy parameters and three Euler angles specifying orientation of the symmetry planes of the orthorhombic medium. In the case of a dipping reflector, the formulas also depend on the apparent dip angle of the reflector.

Whole paper

The reprint can be obtained from Ivan Psencik.

Geophysics, 82 (2017), WA23-WA32.