Holographic Method for Separating Acoustic Logging Waves

A holographic method for filtering the casing wave during acoustic logging while drilling is proposed. The method is based on application of a two-dimensional Fourier transform to the phase-correlation diagram. The efficiency of the method is demonstrated by processing acoustic signals of the three-element device “Horizon-90-WAL,” which is designed to measure the parameters of the elastic waves generated in rocks by an electro-acoustic emitter. The phase-correlation diagrams, holograms, and spectrograms of the received signals before and after filtering the casing wave are presented. The method made it possible to identify longitudinal and transverse waves and estimate their propagation rates in the rock.