GB1362670A - Seismic record sections - Google Patents

Abstract

1362670 Displaying seismic data WESTERN GEOPHYSICAL CO OF AMERICA 20 Dec 1971 59180/71 Heading H4D Wavelength variations in the acoustic waves propagated through subsurface formations of the earth during seismic exploration are represented on a coloured, depth-scale seismic record section as chromaticity variations. This enables received wavelets of the same frequency and associated with reflections from formations of different velocity characteristics to be distinguishably displayed, (Fig. 2B), whereas on a conventional time-scale section coloured according to wavelet frequency they would be indistinguishable (Fig. 2A). In the Fig. 1 system, data from a field seismic record are conventionally processed at 10 (e.g. edited, composited, cross-correlated) to reduce noise, then converted from a time-scale to a depth scale in a converter 14 programmed with RMS velocity data. Converter 14 output is split into wavelength bands by filters 16, 18, 20. The ratio of the energies of the filter outputs and the overall energy are determined by comparator 22 to provide respectively hue and lightness control signals which control respectively the beam mean vertical position and brightness in a cathode ray tube 26. The beam is oscillated horizontally, and slightly about this mean vertical position, by sweep generator 35, to illuminate a rectangular strip of a multicolour filter on the tube faceplate. The illuminated strip is imaged by optics 40 as a line on to a colour-sensitive recording medium 42 supported on a rotating drum 44. Individual colour projectors may be used instead of tube 26, or wavelength filters 16, 18, 20 may be used in sequence with medium 42 receiving a multiple exposure through respective colour filters used in sequence. There may be more or fewer wavelength filters, and conventional variable-amplitude or variable-area traces may be superimposed on the coloured display.