GB1324863A - Three dimensional coomon depth point exploration - Google Patents

Abstract

1324863 Seismic exploration TEXAS INSTRUMENTS Inc 28 Aug 1970 [28 Aug 1969] 41517/70 Heading H4D In a seismic exploration system, for providing three-dimensional common depth point (CDP) coverage of the sub-surface, seismic detectors are located along a plurality of spaced apart parallel lines and a plurality of seismic wave sources are located along each of a plurality of lines substantially normal to the said parallel lines. In the Fig. 1 example seismic waves are generated (by dynamite shots or truck-mounted vibrating, gas exploder or weight dropping apparatus) at a line of locations 28a to 28f sequentially, then at line 30a to 30f, and so on, and the outputs of geophone lines 12a-12x, 14a-14x &c. are recorded at 24 on a multi-trace recorder or recorders. Considering sub-surface point 40, it will reflect waves from source 34a to geophone 22a, from source 32a to geophone 22b and so on to give CDP coverage of point 40 in a vertical plane parallel to the lines of geophones. Similarly it will reflect waves from source 34b to geophone 20a, from source 34c to geophone 18a and so on to give CDP coverage of point 40 in a vertical plane generally perpendicular to the lines of geophones. In practice the number of sources or geophones per line may differ from the number shown and the lines are moved along a traverse according to the " roll-along " technique. The source array may be arranged between two geophone arrays like the geophone array shown, with the source locations aligned with the lines of geophones instead of laterally offset as in Fig. 1 (Fig. 5, not shown). The recorded data enables the estimation of static corrections and may be processed to enhance the signal-to-noise ratio. Processing procedure mentioned are migration, mapping, velocity determinations, compositing, mixing, coherence filtering, diversity stacking and velocity combination, and these may be performed by a digital computer.