Method of Effective Specular Points
Testing with real data.
Here the Method of Effective Specular Points is illustrated with simplified but well-verified experiment based upon real marine data (Fig.7): a sea-bottom is a target under artificial assumption that a speed of sound in the water is unknown. The problem is to find the speed and to get a depth image of a sea-bottom, using a sparse subset of seismic records: (21 locations of sources/receivers with x = 150 m on the segment of the line profile of 3000 meters (Fig.4, left). All other records have been used as a control subset: on the base of the reconstructed sea-bottom profile, the rms-misfit of traveltimes measured and those along Fermat's extremals/lines is evaluated - the decreasing of the misfit can testify for improving the image.The result is as follows:* the velocity estimated is 1499 m/s; * standard deviations of traveltimes are 0.032 sec for the 1-st image, 0.028 sec for the 2-nd and 0.025 sec for the final images respectively. Fig. 7. Real marine data processing.* Segment of the "near 0-offset" gather (offset is equal to 101 m): left;* objective function yields an estimate of the sound speed in water: 1499 m/s ( in the middle), and* sequential depth images of the sea bottom are displayed on the right.NB! "Acquisition" is similar to that used for 2D synthetic experiment (Figure 5): a regular source-receiver grid with distance 150 m; in comparison with the standard acquisition the data set in use is reduced in more than 30 times.
References:Ryzhikov, Gennady and Biryulina, Marina, 1996
Method of effective specular points
58th Mtg. Eur. Assoc. Expl Geophys.,
Extended Abstracts, 96, Session: P-134
Biryulina, Marina and Ryzhikov, Gennady, 2000
Imaging of reflectors under uncertainties in macromodel
62nd Mtg. Eur. Assoc. Expl Geophys.,
Extended Abstracts, Session: B-55