Matching and merging high-resolution and legacy seismic images

Measuring time shifts

After balancing the spectral content, we attempt to account for possible time shifts of the high-resolution image relative to the legacy image, which can be caused by changes in acquisition and processing parameters. We measure this shift using local similarity scanning (Fomel, 2007; Fomel and Jin, 2009). In this method, we detect the relative time shift by first calculating the local similarity at different time shifts of the high-resolution image relative to the legacy image (Fomel and Jin, 2009). From this, the trend of the highest similarity is picked and represents the relative time shift between the two images.

Next, we apply the estimated time shift to the original high-resolution image--the frequency content is only degraded for the purpose of finding the time shift that best aligns the signal content between the two images. The differences between the two images before and after the time shift correction are shown in Figure 5, and demonstrate a noticeably better match resulting from the time shift.

diff0,diff1
Figure 5. Difference between the legacy and smoothed high-resolution images before (a) and after (b) aligning the data sets. Before accounting for time shifts, much of the signal content did not align in time, so coherent reflections were subtracted out. After accounting for time shifts, the reflections are more aligned, so much of the subtracted information is noise.

Matching and merging high-resolution and legacy seismic images