3D volumetric multispectral estimates of reflector curvature and rotation

One of the most accepted geologic models is the relation between reflector curvature and the presence of open and closed fractures. Such fractures, as well as other small discontinuities, are relatively small and below the imaging rangeofconventionalseismicdata.Dependingonthetectonic regime, structural geologists link open fractures to either Gaussian curvature or to curvature in the dip or strike directions. Reflector curvature is fractal in nature, with different tectonic and lithologic effects being illuminated at the 50-m and1000-m scales.Untilnow,suchcurvatureestimateshave been limited to the analysis of picked horizons. We have developed what we feel to be the first volumetric spectral estimates of reflector curvature. We find that the most positive and negative curvatures are the most valuable in the conventional mapping of lineations — including faults, folds, and flexures.Curvatureismathematicallyindependentof,andinterpretatively complementary to, the well-established coherence geometric attribute. We find the long spectral wavelengthcurvatureestimatestobeofparticularvalueinextracting subtle, broad features in the seismic data such as folds, flexures, collapse features, fault drags, and under- and overmigrated fault terminations. We illustrate the value of these spectral curvature estimates and compare them to other attributes through application to two land data sets — a salt domefromtheonshoreLouisianaGulfCoastandafractured/ karsteddatavolumefromFortWorthbasinofNorthTexas.

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