Instantaneous Q (Quality Factor)
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.
- 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
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
Barnes suggests that the instantaneous quality factor q(t) can be defined by the expression:
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.
- 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.