Automated diffraction delineation using an apex-shifted Radon transform

Diffraction arrivals are important data that have increasingly been used to delineate the sources of diffractors and to explore subsurface discontinuities. In prestack data, diffractions are both zero- and non-zero offset hyperbolas while reflections are only zero-offset hyperbolas. An iterative algorithm using an apex-shifted Radon transform (ASRT) approach is presented in this paper that uses the diffraction hyperbolic trajectory similar to that of prestack time migration in order to locate diffractors and to estimate their corresponding background velocities. Because diffraction energy is generally weak in seismic data and particularly in prestack data, noise attenuation and edge enhancement methods are applied on the instantaneous phase of the seismic data instead of the amplitude data. This means that the phase data are input to the ASRT algorithm. The method is then tested on two synthetic datasets (a point-diffraction model with randomly distributed diffractors and the 2D BP/SEG salt model) and one real data example. Results show that this method can locate the diffractors reasonably well on the rough surfaces of the salt dome and the discontinuities associated with structures such as paleo-channels and faults. Our analysis of the estimated velocities suggests that they are generally valid for diffraction delineation; however, the accuracy of the estimation decreases as background velocity and depth increase.