Abstract: Geologic Interpretation of Seismic-Attribute Measurements

R. E. Sheriff, M. T. Taner

Seismic data contain much geologically meaningful information in addition to the arrival time and apparent dip of reflections, which classically have represented most of seismic interpretation. Information as to stratigraphic variations and hydrocarbon accumulations increasingly is being extracted from seismic-velocity and reflection-amplitude measurements and variations in seismic frequency and reflection-wavelet character with geographic position. Most recently, inversion of seismic data into instantaneous velocity has become possible in a quantitative manner.

Attribute analysis involves calculating (1) the amplitude of the envelope of the seismic trace (reflection strength); (2) instantaneous phase, a sensitive indicator of discontinuities such as caused by faults, pinchouts, onlap, offlap, unconformities, etc.; (3) instantaneous frequency and weighted frequency, useful in correlation and in delineating hydrocarbons; and (4) apparent polarity.

Continuous high-resolution velocity analysis involves calculating the stacking velocity and the instantaneous velocity for every CDP point and every sample point without the averaging which destroys the local significance of the measurements.

Seischrome displays allow the interpreter to see the variation in these many variables in a quantitative manner and see their interrelations. They bring attention to variations in geology which are not otherwise evident and focus on the exact point where changes occur.

AAPG Search and Discovery Article #90961©1978 AAPG Annual Convention and Exhibition, Oklahoma City, Oklahoma