Image Number 11 for United States Patent #4210966.
At least four waveforms representative of sonic waves obtained from an acoustic investigation of a borehole with at least four sonic receivers are combined to automatically measure a parameter of a wave present in the waveforms. The waveforms are derived from sonic receivers which are selectively spaced from each other as well as the sonic transmitter whose sonic pulses caused the sonic waves. Several techniques are described to measure acoustic wave parameters such as the interval travel time of compressional and shear waves for open or cased boreholes. In accordance with one technique a multiple fold correlation process and apparatus are described to measure the acoustic wave parameter.