Real data results

We use a portion of the real data set from the Ocean Bottom Seismograph (OBS) acquisition above the Alba oil field. The Alba oil field is located in the UK North Sea and elongates along a NW-SE axis. The oil reservoir is 9 km long, 1.5 km wide, and up to 90 m thick subsea Newton and Flanagan (1993). The 3-D OBS data set has been already preprocessed and separated into a PP and a PS section. The subset of the data set consists of 250 inline CMPs, 50 crossline CMPs, 200 inline half-offset, and 40 crossline half-offset.

This section compares the result of the traditional method with the proposed method. The traditional method uses Normal moveout plus stacking to obtain the common-azimuth data cube, followed by PS common-azimuth migration, we refer to this method as PS-NoMoRe. The proposed method uses the data regularized using PS-AMO followed by PS common-azimuth migration, we refer to this method as PS-AMORe.

Figure 2 shows the first comparison between the PS-NoMoRe result (left) and the PS-AMORe result (right). From top to bottom four depth slices at 300, 400, 500, 600 m. Note that the acquisition artifacts are stronger in the PS-NoMoRe result than in the PS-AMORe result. At a depth of 600 m the acquisition artifacts are no longer present in the PS-AMORe result.

 

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Figure 2 Comparison for several depth slices, of the PS-NoMoRe result (left) and the PS-AMORe result (right). Note how the acquisition artifacts are healed in after the PS-AMO correction and they are gone at a shallower depth with respect to the NMO correction.

The following results and comparison focus between the relative depths from m and 1300 m. Figures 3 and 4 correspond to the PS-NoMoRe and the PS-AMORe results, respectively. The ovals marked as ``A'' in the inlines present events that are stronger in the PS-AMORe result and are not present in the PS-NoMoRe result. Note first at the very top of the ovals that the reflectors are more clearly defined after PS-AMORe. Right underneath the mark ``A'' inside the ovals there is an event in the PS-AMORe result that can not be followed in the PS-NoMoRe result. The same can be said about the main event at depth 720 right where the inline and crossline sections intersect. The ovals marked as ``B'' also presents more continuity in the events using PS-AMORe, primarily the event at a depth of 720 m. The ovals marked as ``C'' in the depth slices shows a channel in the PS-AMORe result that is not clear using PS-NoMoRe.

 

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Figure 3 3-D image displayed with depth slice at 720 m, inline section from crossline=175 m, and crossline section from inline=4650 m. This result corresponds to the PS-NoMoRe process.

 

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Figure 4 3-D image displayed with depth slice at 720 m, inline section from crossline=175 m, and crossline section from inline=4650 m. This result corresponds to the PS-AMORe process.

Figures 5 and 6 show other sections on the PS-NoMoRe result and the PS-AMORe result, respectively. The geological feature marked by ovals ``A'' is better defined in the PS-AMORe result than in the PS-NoMoRe result. At the reservoir level, the ovals marked as ``B'' and ``C'' show the reservoir with better horizontal continuity and stronger amplitude after PS-AMORe process.

 

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Figure 5 3-D image displayed with depth slice at 720 m, inline section from crossline=175 m, and crossline section from inline=2150 m. This result corresponds to the PS-NoMoRe process.

 

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Figure 6 3-D image displayed with depth slice at 720 m, inline section from crossline=175 m, and crossline section from inline=2150 m. This result corresponds to the PS-AMORe process.