Dr. Tom Smith presenting on Machine Learning at the 3D Seismic Symposium on March 6th in Denver
What is the "holy grail" of Machine Learning in seismic interpretation? by Dr. Tom Smith, GSH Luncheon 2018
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

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.