Calculation of precise time delay between fast and slow shear waves based on horizons and DTW

The particle motion in a shear wave is perpendicular to the direction of propagation. An incident shear wave propagating in fracture-induced anisotropic media will split into a fast shear wave and a slow one, which is referred to as shear-wave splitting. The time delay between the fast and slow waves, which is generally proportional to fracture density, may be calculated using two methods: manual horizon picking and cross correlation. Due to the low signal-to-noise (S/N) ratio of shear-wave data, any single method cannot yield desired results. Therefore, we propose a horizon-based method for precise calculation. Large-scale time delays will be calculated first based on marker horizon tracking. For secondary horizons between two makers, a dynamic time warping (DTW) algorithm is used to calculate small-scale time delays. The time delays of both scales would then be combined for the time correction of slow shear waves. A case study confirms the effectiveness of the method for shear-wave data with low S/N ratio.