Dictionary:Instantaneous q factor

{{#category_index:T|Instantaneous Quality Factor}} The instantaneous quality (Q) factor is a seismic attribute and is the ratio of instantaneous frequency to twice the instantaneous bandwidth.This Q computation is the short wavelength variation of the Q value, therefore, it gives relative values.

$q(t)={\frac {-\pi Freq(s)}{decay(t)}}$

Where $decay(t)$ is the instantaneous decay rate, which is defined as the first derivative of the trace envelope divided by the trace envelope envelop providing an expression:

$q(t)={\frac {-\pi Freq(s)E(s)}{\frac {dE(s)}{dt}}}$

Where $Freq(s)$ is the instantaneous frequency while $E(s)$ is the trace envelope and ${\frac {dE(s)}{dt}}$ is the first derivative of the trace envelope.It is also a physical attribute with a strong relation to porosity, permeability, and fracture.

• Indicates 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.
• Indicates relative absorption characteristics of beds.
• It is a transmissive attribute; its various wavelength components should be estimated in a similar way to the average velocity and velocity inversion procedures.