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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Attenuation

Attribute Description:  Attenuation attempts to represent the rate of absorption of the seismic energy as it goes through the earth.  The absorption, transmission and reflection of sound directly relate to rock type and its impedance value as reflected by P and S wave velocity and density. These are effected by conditions such as porosity, saturation and pore pressure so it can be useful in reservoir characterization.

Interpretation Use:  This attribute may provide value by

  • Localizing Lithology types
  • Providing an indication of pore pressure, fluid saturation and porosity

Recommended Colorbar: 

In this example, we are using “Average Energy”, a spectral based colorbar. This attribute puts out all positive values, in this example from 0 to 462. The brighter colors represent the higher rates of attenuation while the darker blues and greens represent the lower rates of attenuation. As seen in the example below, the deeper rocks attenuate the sound less, which makes sense as they are more compacted, and have a higher velocity than the shallower rocks. The spectrum reflects the large number of “0” values

Attenuation - 1.png

Example:

Vertical Seismic Section using Attenuation

Vertical Seismic Section using Attenuation

Time slice of Attenuation

Time slice of Attenuation

Frequency Spectrum for Attenuation


Frequency Spectrum for Attenuation

Computation: 

Attenuation is computed by dividing the first derivative of envelope by smoothed frequency:

Attenuation - 5.png

The smoothed frequency is used due to the presence of spikes in normal instantaneous frequency.

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.