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

Phase Breaks

Attribute Description:  The Phase Breaks signal marks phase discontinuities by picking peaks from a difference signal that is constructed by subtracting the phase signal from the smoothed phase signal.  It extracts a peak at the -180-degree phase point of the real trace and creates a 3 sample spike to designate that location. The result reflects the discontinuities in the phase and is amplitude independent. For greater detail read “Banded Attributes Overview".

  This is a display of amplitude a(t) and phase breaks. Notice how each phase break matches a trough in the amplitude display

This is a display of amplitude a(t) and phase breaks. Notice how each phase break matches a trough in the amplitude display

Interpretation Use:  This attribute may provide value by:

  • Providing improved “trough” interpretation
  • Showing boundaries of sequences and depositional environments
  • Showing discontinuities and faults
  • Making normal event interpretation easier as amplitude is removed

Recommended Colorbar:

Since the distribution of this data is all positive, and amplitudes reside in a 3 trace spike, a wraparound colorbar gives a trace-like view and highlights discontinuities.

  Example Colorbar and amplitude spectrum

Example Colorbar and amplitude spectrum

Example:

 Vertical display of Phase Breaks

Vertical display of Phase Breaks

 Time slice of Phase Breaks

Time slice of Phase Breaks

 Frequency Spectrum

Frequency Spectrum

Computation: Phase breaks is computed in several steps.  First, smooth phase is computed as

Phase Breaks - 06.png

where b(t) is a boxcar function with a length of T samples and height 1/T

Phase breaks are computed by convolving a 3-sample Hanning smoother han(t) with the Hilbert transform of the difference between the phase and the smoothed phase.

References:

  • Taner, M. T., 2001, Seismic attributes:  Canadian Society of Exploration Geophysicists Recorder, 26, no 7.
  • Tom Smith, Paradise Instantaneous Attributes, 2017, Paradise Help