Patent ID: 8004932

Claim:
A method of characterizing shear wave anisotropy in a formation, comprising: obtaining cross dipole measurements over a range of frequencies over a range of depths in a borehole penetrating the formation; estimating a first azimuthal direction of a fast shear mode near the borehole using a high frequency component of the measurements; estimating a second azimuthal direction of a far-field fast shear mode using a low frequency component of the measurements; and using a model in which there is a gradual transition of the azimuthal direction of the fast shear mode from near the borehole to the far field, the estimated first azimuthal direction and the estimated second azimuthal direction for at least one of: (i) estimating a property of a stress field in the formation, or (ii) providing an indication of intrinsic anisotropy of the formation.