Interpretation of Hard Rock Seismic Data Using 3D Prestack Diffraction Imaging

Abstract

Mineral deposits are associated with geological settings characterized by discontinuities and complex structural heterogeneities such as fracture zones, small-scale objects, intrusive and steeply dipping structures. Therefore, detecting such heterogeneities is of primary interest in mineral exploration. Usually, the scale and shape of such heterogeneities cause the seismic energy to diffract rather than reflect. Despite the natural lack of reflectors and potentially abundant number of diffractors, there are only few case studies of diffraction imaging in hard rock environments with almost no examples of diffraction imaging in prestack domain. Herein, we fill this gap by implementing a 3D prestack diffraction imaging technique to detect point diffractors in hard rock environment. The technique includes computation of diffraction traveltime curves followed by semblance analysis along the curves, with high value of semblance corresponding to high diffractivity.

The performance of the method is demonstrated on a 3D synthetic seismic data and applied to a 3D field seismic data set recorded over Kevitsa mineral deposit in the northern Finland. The results of the 3D prestack diffraction imaging method suggest that diffractivity is a powerful attribute that can be used with other seismic attributes for the interpretation of seismic data in hard rock environments.