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Digital shaping filters are designed for the purpose of maximizing the resolution In seismic data while minimizing the adverse affects that Inverse filters usually have on the slgnal-to-noise ratio. Knowledge of the basic propagating seismic wavelet shape is required. In marine data, this is most often obtained by analysis of sea-floor reflections.These shaping filters provide the additional advantages of reflection polarity clarification and precision in reflection onset timing.

This pane~-was Ilreparedforpresentatipn at the Sixth Annual Offshore Technology Conference to be held in_Houston, Tex~, Ma.y [6][7][8] 1974. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be cOIlied. Such use of an abstract should contain consIlicuous~cknowledgment of where and by whom the Ilalleris Ilresented. ABSTRACT Recent developments in the recording and processing of seismic data have permitted the enhancement of certain diagnostic characteristics which have been found to be direct indicators of the presence of hydrocarbons within the sedimentary section. Anomalous changes in the amplitude, frequency, and phase of the seismic wave and variations in the rock velocities and apparent structural attitude of the beds can all be used for recognizing the presence of oil and gas. Under certain conditions it is possible to identify the actual fluid contact within a formation. SFISMIC HYi3ROCARR0N lNI)lCATflR< AND Mf)13Fl$ .

The various factors controlling the “character” of reflection seismograph records are so numerous and so complex that it is very difficult to isolate and investigate each of them experimentally. One of these factors is the frequency discrimination due to multiple reflections in the low velocity zone (“weathered layer”). With a few simplifying assumptions this problem reduces to one already treated in the classical theory of acoustics. It is shown that for a given weathering thickness the transmission is a periodic function of frequency. The ratio of the maximum to the minimum energy transmission is nearly equal to the square of the ratio of the specific acoustic impedance of the high velocity to that of the low velocity material. The phase lag due to the presence of the weathered layer is shown to be a non‐linear function of the weathering thickness for any given frequency. Graphs of transmission as a function of frequency are shown for various thicknesses of the low velocity zone.

No abstract