A computational system is described that detects seismic reflections recorded digitally on magnetic tape, performs migration if desired, and plots the information in cross‐section form. The detection or “picking” philosophy is based on the selection of the time positions of either all peaks or all troughs in the set of traces which constitutes the seismic section of interest. A lateral continuity search “correlates” these peaks or troughs across the traces in order to define reflection segments. All reflection segments which span at least three consecutive traces are stored in digital format on magnetic tape. They are given a grade which is the product of their spatial span and mean amplitude. A time‐varying grading threshold is employed to limit the number of reflection segments which are output to an automatic plotter or carried for subsequent processing such as computer migration. Several examples of these automatically derived cross sections are shown and compared with the original variable‐area record sections. This system is readily extended to multiline or grid data. Thus it is feasible to generate and display automatically three‐dimensional interpretive aids such as isochrons and isopachs.
A new data processing technique is suggested to estimate the delay time between initially uptraveling energy which is reflected once at the earth's surface and initially downtraveiing energy on earthquake seismograms. The method uses optimum inverse filter together with a criterion that measures the simplicity of a seismic signal convolved with an inverse filter. The inverse filters are designed to extract primary energy in the presence of surface reflected energy and random noise on the basis of a least-mean-square error criterion. Filter design Is dependent on the delay time between primaries and surface reflected events, their amplitude ratio and noise to signal power ratio. The simplicity criterion was devised on the assumption that a maximum in the concentration of normalized seismic signal energy above a minimum level indicates which filter was most correctly designed. This is visualized as an expression of the hypothesis that the primary seismogram is generated by a few large discontinuities, rather than by many minor boundaries.The technique was applied to band-limited synthetic signals that contained several primary-secondary pairs in the presence of random noise. Of 27 synthetic signals which were analyzed, the procedure successfully selected the correct delay time in 22 cases,
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