Abstract: The process of obtaining seismic data includes deploying a seismic energy source and seismic receivers, actuating the source, and detecting seismic energy resulting therefrom at the receivers. The process further includes digitally sampling seismic energy detected at the receivers indexed with respect to time to form a plurality of traces and sorting the traces to form a plurality of shot gathers. In addition, the process includes applying a depth migration technique to the shot gathers to generate two images according to the cross-correlation imaging condition (I0) and the gradient-based imaging condition (I1) for each shot gather. A reflection angle (?) or a general domain parameter (?) is computed at each subsurface position and the images are mapped according to the corresponding reflection angle or the general domain parameter to form common image gathers. Amplitude correction is applied to common image gathers and the images and common image gathers are stored on non-transitory computer-readable media.

Abstract: The process of obtaining seismic data includes deploying a seismic energy source and seismic receivers, actuating the source, and detecting seismic energy resulting therefrom at the receivers. The process further includes digitally sampling seismic energy detected at the receivers indexed with respect to time to form a plurality of traces and sorting the traces to form a plurality of shot gathers. In addition, the process includes applying a depth migration technique to the shot gathers to generate two images according to the cross-correlation imaging condition (I0) and the gradient-based imaging condition (I1) for each shot gather. A reflection angle (?) or a general domain parameter (?) is computed at each subsurface position and the images are mapped according to the corresponding reflection angle or the general domain parameter to form common image gathers. Amplitude correction is applied to common image gathers and the images and common image gathers are stored on non-transitory computer-readable media.

Abstract: A low-cost general method to perform subsalt velocity analysis is provided. For instances where sediment velocity structure is relatively simple, the method includes a single one-time redatuming to the base of salt, using existing prestack wave equation tools. For instances where the sediment velocity structure has a variable topography, the method includes multi-step redatuming to the base of salt. The method is designed to completely remove the salt-sediment overburden effects, and redatum the surface seismic data to a flat arbitrary subsalt datum, removing the complexity of the wavefield caused by the salt bodies. Once having obtained a simplified wavefield by stripping off the effects of the complex overburden, less expensive Kirchhoff imaging algorithms are employed for performing subsalt velocity model building.