DETERMINATION OF DIPOLE SHEAR ANISOTROPY OF EARTH FORMATIONS

摘要

A method for determining formation shear slowness of formations surrounding an earth borehole that includes: transmitting sonic energy into the formations from a dipole source in the borehole; measuring signals from orthogonal wave components that have traveled through the formations at each of a plurality of receiver locations in the borehole, spaced at a respective plurality of distances from the transmitter location; transforming the signals to the frequency domain and separating dispersive and non- dispersive portions of the transformed signals; and determining fast and slow shear slowness of the formation from the low frequency asymptotes of the dispersive portions of the transformed signals. Related methods for determining shear directionality and the magnitude of anisotropy of anisotropic formations surrounding an earth borehole and associated apparatus are also described.