Amplitude -> E_pos_strike and E_neg_strike
Attribute Description: The E_pos_strike and E_neg_strike attributes are additional curvature attributes that can be used to complement geologic information extracted from E_pos and E_neg attributes (refer to Curvatures -> Amplitude -> E_max, E_min, E_pos, and E_neg attributes description section).
Interpretation Use: The E_pos_strike and E_neg_strike are estimates of the component curvature projected along the strike direction of a tangent plane to the surface. These additional curvature attributes can be used to identify stratigraphic features, faults, and fractures (Chopra and Marfurt, 2007). Attribute results are better analyzed in plan view or draped over a horizon displays.
Recommended color palette: For the E_pos_strike and E_neg_strike attributes a divergent color scheme is suggested. The midpoint color is white to emphasize the progression outward two different dark hues. In the examples below, the dark hues were set to blue and red to better highlight geologic features. We suggest using the histogram of values to guide setting color value thresholds.
Computation: The E_pos_strike and E_neg_attributes strike are computed using this workflow:
Input data → Estimates of reflector dip → Estimates of coherent energy gradients through measurements of similarity → Curvature amplitude data
The process can be summarized as follows (AASPI documentation):
- Take the Inline Dip, Crossline Dip, and seismic amplitude volumes as input data (refer to Filter Dip Components -> Inline Dip, Crossline Dip, and Confidence attribute description section)
- Run a similarity computation (refer to Similarity attributes description section)
- Computing the covariance matrix from the complex trace signal
- Decomposing the covariance matrix into its corresponding kth eigenvalue and vth eigenvectors. Then normalize the eigenvectors to be unit length
- Estimating a scaled principal component, where the scale is the inner product or correlation of the eigenvector
- Generate estimates of inline and crossline coherent energy gradient
- Use the inline and crossline energy gradients to solve the coefficients of the quadratic surface:
- AASPI documentation, http://mcee.ou.edu/aaspi/documentation/Volumetric_Attributes-curvature3d.pdf
- Chopra, S. and K. J. Marfurt, 2007, Seismic attributes for prospect identification and reservoir characterization: SEG Geophysical development series, 11, 110 – 111.