Abstract: Temporal and/or spatial frequencies of spatially and digitally sampled 2-D or 3-D seismic data above the Nyquist frequency are preserved in full time migration of partial time migration (DMO) of 2-D and 3-D are preserved. Use is made of the fact that migration operators applied to input seismic data produce an output that need not correspond to prespecified temporal or spatial sampling values, and for sufficiently long migration operators, gives substantially uniform sampling at higher rates than the spatial and temporal Nyquist frequencies. Exact values of the partial migrated outputs are accumulated in an output buffer prior to combining them to give a migrated output with high temporal and/or spatial frequencies preserved.

Abstract: Temporal and/or spatial frequencies of spatially and digitally sampled 2-D or 3-D seismic data above the Nyquist frequency are preserved in full time migration of partial time migration (DMO) of 2-D and 3-D are preserved. Use is made of the fact that migration operators applied to input seismic data produce an output that need not correspond to prespecified temporal or spatial sampling values, and for sufficiently long migration operators, gives substantially uniform sampling at higher rates than the spatial and temporal Nyquist frequencies. Exact values of the partial migrated outputs are accumulated in an output buffer prior to combining them to give a migrated output with high temporal and/or spatial frequencies preserved.

Abstract: A method of preserving frequency components in digitally sampled signals exceeding a maximum frequency related to a predetermined digital sample interval. The signals correspond to a plurality of sensors positioned at spaced apart locations, and the signals from each of the plurality of sensors are digitally sampled at the predetermined digital sample interval. The method includes the steps of determining time adjustment values corresponding to each sensor which provide amplitude correspondence between each of the signals generated by each of the sensors in response to different propagation times of energy from an energy source to each of the sensors; adjusting a time of acquisition of each digital sample from each of the sensors by applying the corresponding time adjustment value to generate time-adjusted samples; and combining all the time adjusted samples into a combined output signal having a sampling time interval smaller than the predetermined digital sample interval.