METHOD FOR DEFINITION OF BOUNDARIES OF SUB-VERTICAL EXPANDED OBJECTS IN GEOLOGICAL ENVIRONMENT

摘要

FIELD: geophysics.;SUBSTANCE: invention relates to the field of geophysics and can be used to map the boundaries of sub-vertical extended objects. Method is proposed for determining the boundaries of sub-vertical elongated objects in a geological medium, according to which in the study area, two horizontal, with identical amplitude-frequency responses (AFR) of X and Y seismic detectors are installed at each measurement point i, which sensitivity axes are mutually orthogonal. Sensitivity axes of all X seismic detectors have the same orientation direction, and the sensitivity axis of all Y seismic detectors have the same orientation direction. Distance between measurement points i is no more than the minimum depth of a given range of studies. Performing synchronous recording of micro-seismic signals consisting of Rayleigh waves with X and Y seismic detectors during the registration time T determined by the period of stationarity of the micro-seismic signal horizontal components. Then calculating an averaged over the recording time T power spectrum S_Xi(f) of horizontal components of signals of X seismic detectors and the power spectrum S_Yi(f) of the horizontal components of the signals of the Y seismic detectors at each measurement point i. Determining the obtained power spectra ratios at each measurement point i S_Xi(f)/S_Yi(f), and then building power ratio map S_Xi(f_j)/S_Yi(f_j)for each selected frequency f_j, the interpolation surface of the power spectra S_Xi(f_j)/S_Yi(f_j) ratio values and a modulus map of the interpolation surface gradient. Binding of each obtained map of the values of the ratio of the power spectra S_Xi(f_j)/S_Yi(f_j) to the depth H_j is carried out using formula H_j = 0,6–0,8V(f_j)/f_j, where V (f_j) is the mean phase velocity of the Rayleigh wave, and f_j is the frequency in the spectrum. Boundaries of the sub-vertical extended geological objects are determined from the values of the gradient modulus exceeding 2/3 of the maximum value of the gradient modulus.;EFFECT: technical result is an increase in the reliability of determining the sub-vertical boundaries of objects in the geological environment due to the fact that the horizontal components of the random micro-seismic signal are physically equivalent to each other and the laboriousness of the measurements is reduced.;1 cl, 1 dwg