Diffraction imaging of sediment drifts in the Canterbury Basin, New Zealand




Al-Hadab, Salah Ahmad

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Analysis of scattered, or diffraction energy (the seismic response of small-scale objects) in the seismic data from Canterbury Basin, New Zealand reveals additional geological information about depositional patterns in sedimentary deposits. Diffrac- tion images from the seismic response for Canterbury Basin provide complementary interpretation tools to the conventional specular reflection images. To image diffrac- tions for a dataset from Canterbury Basin, I take the following steps: First, I attenuate multiples using a surface multiple prediction algorithm to predict multiples and apply regularized nonstationary regression to adaptively subtract the predicted multiples. Next, I separate diffractions using the plane-wave destruction method. The plane- wave destruction method removes conventional reflected energy in order to enhance the diffracted energy. I then apply a velocity continuation method on diffraction data to estimate migration velocities and then migrate the data using Kirchhoff migration in the dip-angle-gather domain. The resultant conventional and diffraction images are improved images suitable for geological interpretation of prograding sediment drifts.



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