f Extra fine Layering

In a layered medium the compressional slowness perpendicular to the layers is frequency dependent. In the high frequency limit when all layers are much larger than the wavelength the slowness is the mean slowness. At the other extreme when all layers are thin the slowness can be determined from the Backus equation. In order to predict low frequency velocities from measurements made in the high frequency limit the layering must be accurately defined. However, there exists a wide range of layer thicknesses which are beneath the definition of sonic tools yet are thick with respect to the logging wavelengths. This layering will not contribute to any low frequency velocity or anisotropy estimation.