Diffraction separation by plane-wave prediction filtering
Kong Xue1, Wang De-Ying2, Li Zhen-Chun3, Zhang Rui-Xiang1, and Hu Qiu-Yuan1
1. College of Petroleum Engineering, Shengli College, China University of Petroleum, Dongying 257061, China.
2. College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China.
3. School of Geosciences, China University of Petroleum (Hua Dong), Qingdao 266555, China.
Abstract Seismic data processing typically deals with seismic wave reflections and neglects wave diffraction that affect the resolution. As a general rule, wave diffractions are treated as noise in seismic data processing. However, wave diffractions generally originate from geological structures, such as fractures, karst caves, and faults. The wave diffraction energy is much weaker than that of the reflections. Therefore, even if wave diffractions can be traced back to their origin, their energy is masked by that of the reflections. Separating and imaging diffractions and reflections can improve the imaging accuracy of diffractive targets. Based on the geometrical differences between reflections and diffractions on the plane-wave record; that is, reflections are quasi-linear and diffractions are quasi-hyperbolic, we use plane-wave prediction filtering to separate the wave diffractions. First, we estimate the local slope of the seismic event using plane-wave destruction filtering and, then, we predict and extract the wave reflections based on the local slope. Thus, we obtain the diffracted wavefield by directly subtracting the reflected wavefield from the entire wavefield. Finally, we image the diffracted wavefield and obtain high-resolution diffractive target results. 2D SEG salt model data suggest that the plane-wave prediction filtering eliminates the phase reversal in the plane-wave destruction filtering and maintains the original wavefield phase, improving the accuracy of imaging heterogeneous objects.
This research was funded jointly by the National Natural Science Foundation of China (No. 41104069), the National Key Basic Research Program of China (973 Program: 2011CB202402), the Shandong University Science and Technology Planning Project (No. J17KA197), and the College of Petroleum Engineering in Shengli College China University of Petroleum “Chunhui Project” (No. KY2015003).
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