A 3-D seismic survey provides a volume of closely spaced accurate three-dimensionally migrated data. From this data volume, the seismic interpreter has a wide variety of display options available: two-dimensional slices, both vertical and horizontal, and three-dimensional displays of the data volume itself. Thus the interpreter can study a subsurface feature on a two-dimensional section of chosen orientation or in three dimensions. He has, however, a very large quantity of data to examine before arriving at a final interpretation of the prospect.

Interpretation of Seiscrop (trademark of Geophysical Service, Inc.) horizontal sections provides a fast, convenient, and effective way of interpreting the data volume. Seiscrop sections displayed every 2 or 4 msec and made into a motion picture are used in conjunction with the Seiscrop Interpretation Table to build horizon contour maps directly. Seiscrop sections are an easy and successful means of delineating flat spots or small structures. In "flat" spots which are not quite flat because of lateral velocity gradients, composite Seiscrop sections from more than one record time are used. Seiscrop sections are also used for stratigraphic interpretation.

Seismodel (trademark) Display Unit is a means of viewing many vertical slices through the data volume simultaneously. This permits the interpreter to see structural and stratigraphic features in three dimensions. Each vertical section is on a separate demountable transparent plate. The interpreter removes and marks each plate in turn to develop his interpretation in three dimensions.

Reflection holography is also used to display a 3-D data volume. Many vertical seismic sections are stored on a single holographic plate. The data are then reconstructed

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in three dimensions by illuminating the plate with white light or light rich in the wavelength to which the hologram is tuned.

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