Predicting Fracture Orientations with Volumetric Curvature Gradient Analysis*

Seismic curvature gradient is a useful third-order geometric attribute that has demonstrated its value for subsurface structure analysis, especially fracture detection in fractured reservoirs. However, most recent efforts have been primarily focused on predicting fracture intensity by this attribute; and little has been published on applying it to predict most likely fracture orientation, which is crucial and essential for efficient fracture characterization and modeling. This study presents an algorithm to evaluate both the principal value and principal direction of curvature gradient. First, we develop a computational equation for azimuthal curvature gradient that measures curvature gradient along any given azimuth in 3D space. Then, we implement an azimuth-scanning approach to find local maximums of curvature gradient. The proposed technique allows us to simultaneously generate two volumes of curvature gradient and curvature gradient azimuth. We apply curvature gradient analysis to a fractured reservoir at Teapot Dome in Wyoming and find lineaments not discernable from coherence or curvature attributes. The example demonstrates the potential of this new technology to predict mode and orientation of fractures in the reservoirs.