Watch videos of Presentations from SEG 2017
Using Attributes to Interpret the Environment of Deposition - A Video Course. Taught by Kurt Marfurt, Rocky Roden, and ChingWen Chen
Dr. Kurt Marfurt and Dr. Tom Smith featured in the July edition of AOGR on Machine Learning and Multi-Attribute Analysis
Rocky Roden and Ching Wen Chen in May edition of First Break - Interpretation of DHI Characteristics using Machine Learning
Seismic interpretation and machine learning by Rocky Roden and Deborah Sacrey, GeoExPro, December 2016

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Instantaneous Q (Quality Factor)

Seismic Attribute:

Instantaneous Q is a measurement of the absorption and dissipation of the source energy by the rocks and fluids that it passes through.

This version of instantaneous Q is based on Barnes (1982) suggestion that instantaneous quality factor based on the instantaneous frequency divided by the instantaneous decay rate.

Interpretation Use:

  • Indicates the local variation of Q factor, similar to the relative acoustic impedance computation from the seismic trace.  Longer wavelength variation should be computed by spectral division and added to this attribute.
  • May indicate liquid content by rationing pressure versus shear wave section Q factors
  • Indicate relative absorption characteristics of beds
  • It is a transmissive attribute and is various wavelength components should be estimated in a similar way to the average velocity and velocity inversion procedures
  • a physical attribute with a strong relation to porosity, permeability, and fracture

Recommended Colorbar:

This attribute usually has a flat to the gaussian distribution. Both positive and negative values are presented. Normal seismic colorbars can represent this attribute well, and in this example, we are using a black-red-white-blue-black colorbar

Example colorbar and amplitude spectrum

Example colorbar and amplitude spectrum

Example:

Vertical display of Q

Vertical display of Q

Time slice of Q

Time slice of Q

Frequency Spectrum

Frequency Spectrum

Computation: 
Barnes suggests that the instantaneous quality factor q(t) can be defined by the expression:

Instantaneous Q - 5.png

Where decay is the instantaneous decay rate, which is defined as the derivative of the instantaneous envelope divided by the envelope. Except for a factor of 2π, decay(t) is similar to the instantaneous bandwidth. This Q computation is the short wavelength variation of the Q value; hence, it gives relative values. It is a transmissive attribute, similar to the interval and instantaneous velocities. It is also a physical attribute with a strong relation to porosity, permeability, and fracture.

 

References:

  • Chopra, S. and K. J. Marfurt, 2007, Seismic attributes for prospect identification and reservoir characterization:  Society of Exploration Geophysicists, Geophysical Developments #11.
  • Taner, M. T., 2001, Seismic attributes:  Canadian Society of Exploration Geophysicists Recorder, 26, no 7.
  • Barnes, A.E., 1994, Theory of two-dimensional complex seismic trace analysis: 64th Annual Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 94, 1580-1583.
  • Barnes, A.E., 1990, Analysis of temporal variations in average frequency and amplitude of COCRP deep seismic reflection data: 60th Ann. Internal. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 1553-1556.
  • Barnes, A.E., 1991, Instantaneous frequency and amplitude at the envelope peak of a constant-phase wavelet: Geophysics, 56, 1058-1060
  • Barnes, A.E., 1992, Another look at NMO stretch: Geophysics, 57, in press.
  • Barnes, A.E., 1992, Instantaneous spectral bandwidth and dominant frequency with applications to seismic reflection data: Geophysics.