Prediction ahead of the bit using borehole guided waves

We present a method for seismic prediction ahead of the bit which employs the conversion of borehole guided waves (tube waves) into body waves and vice versa at the borehole bottom. The feasibility of this method, in particular the conversion of borehole guided waves into S‐waves and its directivity, is investigated by means of 2.5D finite‐difference modeling in the time domain. Furthermore, we present a processing scheme which takes into account the characteristics of the involved wave types and test the processing using synthetic data generated by 2.5D finite‐difference modeling.