## 5 Results  
We were able to estimate the quality factor in the DS-2 borehole using both spectral ratio method on the VSP data, as well as the dispersive method used on the acoustic well-log data. In case of the VSP data, we used receivers from a depth range of 45 to 299 m (17 receivers). The results are presented at (Figure 6) in the form of smoothed curves. Smoothing was performed using Savitzky-Golay filtering [39]. The final Q distribution is presented as a median value from all obtained Q curves. We also show the mean value as well as the range of the obtained results (min and max from 17 Q curves). We observe high variability of the obtained Q values, However, all median/mean and min/max curves show a very similar trend. Figure 5: Part of processing flow referring to IQF application. To be able to obtain a meaningful comparison to the Q curve calculated using the dispersive method, we further smoothed the VSP median Q curve using the moving average (Figure 7). The shape of the obtained Q curves is similar, However, due to uncertainty of the frequency of the well-log data, the obtained results differ in value. Figure 6: **(Left panel)**: Q distribution calculated in the frequency range 15–120 [Hz] using mean, median, min and max Q curves after smoothing using Savitzky-Golay filtering. (**Right Panel**): receivers from depths 45–299 m used as reference receivers for Q calculation. Figure 7: Quality factor depth distribution in the DS-2 borehole. Green line is the Q calculated using spectral ratio method on VSP data. Red lines are the Q distributions based on the dispersive method assuming dominant frequency of seismic (VSP or checkshot) data to be 45 Hz, and frequency of logging tool (acoustic logs) to be 20 kHz. Dotted lines (\(+/-20\%\)) shows the possible discrepancy because of uncertainty of real frequencies. The effectiveness of the IQF was tested on M-4 transect stacked sections after migration. For the IQF procedure, we used Q distribution from the spectral ratio method (green line on Figure 7). The obtained results were compared to the seismic section without applying IQF. Several amplitude gains and Q distributions were tested. We used gains of 20, 30, 40 and 50 dB (Figure 8). As for the Q distributions, we used Q values presented at (Figure 7--green line) resampled to equal intervals of 50 ms with the Q value of 25 at depths where we did not have any Q measurements (near surface c.a 200 m). In the second test (Figure 9), we used different values Q factor. The first panel (No. 1) corresponds to PSTM section without IQF applied. On the next panel (No. 2), we used a constant Q of 150 in the whole length of the well. Panel 3 corresponds to the constant Q of 150 but with a value of 25 at the near surface depth. Panel 4, with time variant Q distribution, is our recommended option, see Figure 8. The last panel is the Q value calculated based on the stacking velocities. Figure 8: The results of the IQF procedure tested in several variants of the amplitude gain. Left panel A shows well log data with lithological interpretation, middle section B is the processed zero offset VSP. On the right panels C there are seismic sections with different amplitude gains. Point X shows example of the vertical resolution increase resulting in the separation in whole or in part of some reflections and a noticeably better fit of the seismic image to the attached VSP result. Red frame in section C indicates which amplitude gain was chosen for the degree of vertical resolution enhancement and best fit to the VSP data. By yellow color lines marked Well Tracks, by blue and orange color lines marked Synthetic Seismograms. Based on the analysis of the results, it was found that amplification up to 20 dB does not generally expand the signal spectrum in the higher frequencies, and that the increase in vertical resolution of the section is small (Figure 8 panel C2). A significant increase in resolution is observed for a gain of 30 dB and 40 dB (Figure 8 panel C3 and C4).