TRANSMISSION OF SEISMIC ENERGY DEPTHWARD THROUGH A ROD

To solve many problems involved with improved outlining and stratigrap hy of West-Siberian gas-oil deposits, it is necessary to have a seismi c reflection signal in the form of a single impulse, i.e. its amplitud e spectrum must be constant in the Frequency interval from 6-10 to 100 -120 Hz. In West Siberia the grounds are marshy for the most part, and to provide good quality of seismograms, the reception of waves ought to be performed under the peat layer, while the excitation is to be ma de by means of vertical grouping of sources situated at depths of 30-4 0 m. The last operation is supposed to be carried out using a rod vibr ator with the radiating tip deepening into the ground owing to vibrati on and the static force. The increased attenuation of seismic waves at frequencies of more than 50 Hz is compensated by a resonant increase in the force amplitude in the source at the frequency f(r) approximate to upsilon(st)/(2L), where upsilon(st) approximate to 5000 m/s is the velocity of compressional wave in steel rod. This frequency interval is not wide; therefore, to have an even spectrum of the summary signal in the interval 60-120 Hz the vertical grouping is needed to be perfo rmed at the depths L = 20-32 m with the small step (Delta L approximat e to 1-1.5 m), whereas at the other depths the step Delta L may be cho sen to ensure the best suppressing satellite waves.