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f Euler curvature for observing fracture lineaments
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 11th Simposio Bolivariano - Exploracion Petrolera en las Cuencas Subandinas, Jul 2012, cp-330-00159
Abstract
Over the last several years, seismic curvature attributes have been shown to be very useful in the interpretation of flexures and folds which can often be associated with conjugate faults and fractures. Although many curvature measures that have been introduced, we find the most-positive and most-negative principal curvatures k1 and k2 to be the most useful. All other curvature attributes can be derived from the two principal curvatures. For example, some practitioners have found that the components of apparent curvature projected parallel to the dip azimuth and strike of a dipping plane to be useful in given tectonic and stress settings. In this study we describe the theory and application of Euler curvature, which is a generalization of the dip and strike components of curvature in any user-defined direction. Since reflector dip magnitude and azimuth can vary considerably across a seismic survey, it is more useful to equally sample azimuths of Euler curvature on the horizontal x-y plane, project these lines onto the local dipping plane of the reflector, and compute Euler curvature along a given strike direction. The Euler curvature attribute has the advantage that it can be computed from the conventional final migrated stacked volume to obtain the attributes in different azimuthal directions. In this manner, azimuthally-dependent lineament intensity volumes can be correlated to natural and induced fractures seen in image logs to better quantify the presence of natural fracture sweet spots perpendicular to today’s minimum horizontal stress field. We describe the application of Euler curvature to two different 3D seismic volumes from northeast British Columbia, Canada and show that this attribute is useful for the interpretation of lineament features in desired azimuthal directions.