Dictionary:Trace envelope

ADVERTISEMENT
From SEG Wiki
Jump to: navigation, search
Other languages:
English • ‎español



The trace envelope is a seismic attribute, also known as instantaneous amplitude, is a representation of the amplitude Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle E(t) } of an oscillatory function Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle f(t) } . The quantity Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle E(t) } is of the same order as the absolute value of the amplitudes of the function. Instantaneous amplitude varies approximately between 0 and the absolute value of the maximum amplitude of the trace.

The envelope of seismic signals is independent of the phase and may be related directly to a variety of other trace attributes. The trace envelope of a seismic signal may represent the individual interface contrast or, the combined response of several interfaces, depending on the seismic bandwidth.[1]

The instantaneous amplitude of a seismic trace is related to a form of the trace called the analytic trace, which is the representation of the original seismic trace Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle f(t) } as a complex-valued function Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle s(t) } . Thus the trace amplitude is given by the modulus at each time Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle t }


Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle E(t) = \sqrt{ (\mbox{Re } s(t))^2 + (\mbox{Im } s(t))^2 }}

.


Here, the real part of the analytic trace Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle \mbox{Re } s(t) } , is just the original seismic trace Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle f(t) } . The imaginary part Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle \mbox{Im } s(t) } , also called the quadrature trace, is computed by taking the Hilbert transform of Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle \mbox{Re } s(t) } .

The trace envelope is a physical attribute and can be used as an effective discriminator for the following characteristics:

  • Is proportional to the the acoustic impedance contrast, hence is related to reflectivity
  • Bright Spots
  • Possible gas accumulation
  • Sequence boundaries
  • Thin-bed tuning effects
  • Unconformities
  • Major changes in lithology
  • Major changes in depositional environment
  • Lateral changes indicating faulting
  • Spatial correlation to porosity and other lithologic variations.


References

  1. Taner, Turhan (1992), Attributes Revisited, Rock Solid Images Houston, Texas (published 2000)