Phase moveout method for extracting flexural mode dispersion and borehole properties

Among the dispersive modes encountered in acoustic well logging applications is the flexural mode associated with dipole source excitations whose low frequency asymptote provides the only reliable means of determining shear velocity in slow rock formations. We have developed a phase moveout method for extracting flexural mode dispersion curves from with excellent velocity resolution; the method is entirely data-driven, but in combination with a forward model able to generate theoretical dispersion curves, we are able to address the inverse problem and extract formation and borehole properties in addition to the rock shear velocity. The concept is demonstrated using data from isotropic and anisotropic formations.