Specifics of the underground seismics method using shear waves with reflection separation

The purpose of the study has been to investigate the character of distortion of the reflected signals from different semispaces using the reflection separation procedure. The knowledge of the distortion character and influencing parameters makes it possible to select an effective method of field works and processing. The article presents the underground seismic survey results obtained using the reflected wave method, i.e. common depth point procedure. In the frames of the method, with the participation of the author, an underground seismics method using shear waves with reflection separation has been developed and tested at the Verkhnekamskoye potash salt deposit. With the reflection separation, the signal distortion depends mainly on the distance between the source points lines. Following the direct task of seismic survey, the signals have been modeled for different distances between the reception lines. The study has shown clear regularities in the effect of the distance between the source point lines on the characteristics of the separated reflected signals. The quality of the signal suppression virtually independent on the distance between the source points lines. For an enhanced signal, it is the opposite: depending on the distance between the source point lines, both the signal amplitude and phase get distorted. The signal length also changes: when enhancing the signal coming from below, the elongation happens in the direction of the record beginning, and for a signal coming from above, in the direction of the record end, the quality of signal suppression being almost in no dependence to anything. Vice versa, an enhanced signal is subject to any kind of distortion when the distance between the source point lines changes. Based on the research results, it is possible to choose a distance that provides optimum reflection separation corresponding to a research task.

Verkhnekamskoye potash salt deposit, underground seismics, shear waves, reflection method by a common depth point seismic procedure, reflection separation

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