The medium correlation function is of principal importance in refraction travel-time tomographic inversion. To estimate the correlation function in the vertical direction for the Western Bohemia region, we may use the data from sonic-log measurements in the KTB wells. In the KTB Pilot hole, the P-wave and S-wave slownesses were measured to the depth of about 4 km. In the KTB Main hole, the P-wave slowness was measured to the depth of about 9.1 km, but with considerably increased error below the depth of 7.1 km. The well trajectory under 8.6 km is uncertain and the results of the P-wave slowness measurements are not reliable. In some parts of the well, two measurements of the P-wave slowness overlap, which enabled us to estimate the P-wave slowness measurement errors. The S-wave slowness was measured in the KTB Main hole to the depth of about 7.1 km, and in the depth interval between 7.8 km and 8.6 km. The possibilities to estimate the S-wave slowness measurement errors are limited. Measurements of the density were carried out in some depth intervals only, and they are strongly affected by the well defects.
Seismic waves, velocity model, medium correlation functions, sonic logs, deep drilling, KTB.
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