Trace density

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The number of traces summed into the natural bin in a seismic survey.

Computing fold

We compute fold F according to the equation[1]

F = \frac{\pi X^2_\mathrm{max}}{4 S R}

and trace density T using:

T = F \times \frac{4}{s r} \times 10^6

using the following parameters:

Maximum offset Xmax
the maximum offset recorded in the patch. If this is not known, and you are more interested in the fold at a given depth, then use the target depth instead.
Source line spacing, S
the distance between source lines.
Source interval, s
the distance between the source points along the source lines.
Receiver line spacing, R
the distance between receiver lines.
Receiver interval, r
the distance between the receiver points (sometimes called 'stations') along the receiver lines.

Seismic quality

Cooper suggests a high-level guide for selecting an appropriate trace density, depending on the imaging problem at hand (modified here, based on oil sands applications):

Traces/km2 Application
< 6000 Not advisable
6000 to 18 000 For simple structure plays with good signal:noise
18 000 to 25 000 For stratigraphic and subtuning plays with good signal:noise
25 000 to 100 000 Increasing as signal:noise deteriorates, or as structural complexity increases
100 000 to 1 000 000 Expensive seismic for worst-case scenarios
> 1 000 000 Very expensive seismic for reservoir development and time-lapse applications

References

  1. Cooper, N (2004), A world of reality: Designing land 3D programs for signal, noise, and prestack migration (Tutorial), The Leading Edge, October and December 2004.

See also

  • Fold* — Android app for computing fold and trace density

External links