Geophysical Insights hosting the 2018 Oil & Gas Machine Learning Symposium in Houston on September 27, 2018
Introduction to Machine Learning for Multi–Attribute Interpretation and AASPI attributes - A 1-day, DGS Continuing Education course in Denver, CO on September 18th
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

Envelope Slope

Attribute Description:  Envelope Slope (Time Derivative of the Envelope) shows the variation of the energy of the reflected events. The derivative computed at the onset of the events shows absorption effects. A slower rise indicates larger absorption effects. Events with a sharp relative rise also imply a wider bandwidth, hence fewer absorption effects. This attribute is also a physical attribute and it can be used to detect possible fracturing and absorption effects.

Interpretation Use:  This attribute may provide value because:

  • Sharpness of the rise time relates to absorption in an inversely proportional manner
  • It is affected by the slope, rather than envelope magnitude
  • Lateral variation shows discontinuities,
  • It is used in the computation of group propagation direction. When compared with phase propagation direction, it may indicate dispersive waves.

Recommended Colorbar: 

Since the distribution of this data is Gaussian in nature, with high values at the extremes, a standard seismic colorbar can work.

In this example, we are using a white-black colorbar where white and black highlight the extreme values in the histogram and the intermediate values are displayed in a gray tone. 

  Example Colorbar and Amplitude Spectrum

Example Colorbar and Amplitude Spectrum

Example:

 Vertical display of Envelope Slope

Vertical display of Envelope Slope

 Time slice of Envelope Slope

Time slice of Envelope Slope

 Frequency Spectrum

Frequency Spectrum

Computation: 
A specially designed time domain filter is used to perform the differentiation.

Envelope Slope - 5.png

 

Where * denotes convolution, and diff(t) is the differentiation operator

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.