Obtaining P-Wave and S-Wave Slowness of Formation by Slowness Dispersion Curve

Summary STC method is a traditional method used to obtain P-wave and S-wave slowness of the formation from array waveforms. This method is valid only when the slowness dispersion is low. This paper develop a method to obtain slowness of P-wave and S-wave using slowness dispersion curve, which is little affected by the influence of slowness dispersion. Within the range where frequency is higher than the natural frequency of compressional wave of formation, slowness of slowness dispersion curve is closest to the slowness of compressional wave. Within the range where cutoff frequency is included, the slowness of slowness dispersion curve is closest to the slowness of shear wave. Projecting the slowness dispersion curve onto the slowness axis, we obtain a curve varying with slowness, On this curve, each slowness correspond to a value which peak at the slowness of compressional wave and slowness of shear wave.