Patent ID: 11822029

Abstract:
The present invention is a method to determine an azimuthal orientation of a borehole seismometer sensor performed by a computing device using a control server having a database and an arithmetic function, the computing device performing a method to determine the azimuthal orientation of a borehole seismometer sensor using long-period surface waves in microseisms, including step S100 in which a data collection unit 100 collects continuous waveform data recorded by a borehole seismometer and a reference seismometer; step S200 in which a frequency band setting unit 200 sets a frequency band to be analyzed in the collected continuous waveform data; step S300 in which a filtering unit 300 performs bandpass filtering on the frequency band to be analyzed; step S400 in which a waveform dividing unit 400 divides seismic waveform into waveform segments with preset time units; step S500 in which a phase shift unit 500 shifts the phase of the divided vertical component waveforms by 90°; step S600 in which a waveform calculation unit 600 combines the divided N′ and E′ component seismic waveforms to calculate horizontal components for rotation angles waveform between 0 and 360° from the N′ orientation; step S700 in which a correlation calculation unit 700 calculates a correlation coefficient between the horizontal and vertical component waveforms; step S800 in which a Rayleigh wave orientation determination unit 800 repeats steps S500 to S700 for each divided time domain; step S900 in which an orientation comparison unit 900 performs steps S400 to S800, respectively, with respect to the borehole seismometer data for which the sensor orientation is to be determined and the reference seismometer data for which the sensor orientation is already known; and step S1000 in which a result calculation unit 1000 averages θ determined for each time period to calculate a final result.