Field data examples

The first example is a pre-stack CMP gather, as shown in Figure 2a. In order to apply the EMD based smoother, we first use plane-wave flattening algorithm to flatten the original CMP gather. The local slope used in the plane-wave flattening algorithm is shown in Figure 4. The flattened gather is shown in Figure 2b. We can see some incoherence and some random noise appearing in the flattened gather. However, after applying EMD in the $f-x$ domain, we obtain a quite smooth gather, as shown in Figure 2c. After using the inverse plane-wave flattening algorithm, we can obtain the filtered data (Figure 3a). Figure 3b shows the difference section between Figures 2a and 3a. We can see a tremendous improvement from the zoomed sections, corresponding to the frame boxes A and B, in Figures 5 and 6. The seismic reflections after signal enhancing are obviously much more coherent than the original data. The reference trace for flattening in this example is chosen as the middle trace of the section.

The second example is a post-stack section, as shown in Figure 7a. This data set has much more curved events than the first example. However, by using the plane-wave flattening algorithm, we can still get a well-fattened section that is suitable for applying an EMD based smoothing operator. The reflection-enhanced data is shown in Figure 7b. Figure 7c shows the difference section before and after the smoothing. We also zoom two parts from the original section and filtered section, and show them in Figure 8. The comparison also shows that the proposed seismic reflection enhancing process can help obtain much more continuous events.

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Figure 2. Pre-stack data example. (a) Pre-stack data. (b) Flattened domain using plane-wave flattening. (c) EMD filtering in the flattened domain.

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Figure 3. Pre-stack data example. (a) Seismic reflection enhanced data using EMD. (c) Difference section between Figures 2a and 3a.

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Figure 4. Local slope of pre-stack data example for plane-wave flattening.

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Figure 5. Pre-stack data example. (a) Zoomed sections corresponding to the framebox A in Figure 2a. (b) Zoomed sections corresponding to the framebox A in Figure 3a.

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Figure 6. Pre-stack data example. (a) Zoomed sections corresponding to the framebox B in Figure 2a. (b) Zoomed sections corresponding to the framebox B in Figure 3a.

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Figure 7. Post-stack data example. (a) Post-stack data. (b) Signal enhanced data. (c) Difference.

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Figure 8. Post-stack data example. (a) & (b) Zoomed sections corresponding to the framebox C in Figure 7. (c) & (d) Zoomed sections corresponding to the framebox D in Figure 7.