METHOD OF PICKING OF FIRST ARRIVAL TIME FOR RELIABLE MEASUREMENT OF THE VELOCITY OF ELASTIC WAVE

摘要

PURPOSE: A first-arrival traveltime extracting method for measuring the speed of elastic waves is provided to select a plurality of candidate time points and monitoring time points and to extract first-arrival traveltime by sampling the time points, thereby improving the reliability and the accuracy of extracting the first-arrival traveltime. CONSTITUTION: A first-arrival traveltime extracting method for measuring the speed of elastic waves is as follows. A gap for obtaining a reference time point of the received elastic waves is set(S10). The moment that the received elastic waves are captured by the gap for obtaining the reference time point is obtained as the first-arrival traveltime reference time point(S20). The first-arrival traveltime candidate time point is selected from the time points after the amplitude is stabilized among the time points prior to the first-arrival traveltime reference time point(S30). One or more first-arrival traveltime monitoring time points are additionally selected from the time points close to the first-arrival traveltime candidate time points(S40). Sampling waveforms of the selected first-arrival traveltime candidate time points and the monitoring time point is performed(S50). The first-arrival traveltime is extracted from the time point having a sampling value close to zero(S60). [Reference numerals] (S10) Set a gap for obtaining a reference time point; (S20) Obtain a reference time point for a first-arrival traveltime; (S30) Select candidate time points of a first-arrival traveltime; (S40) Additionally select monitoring time points for a first-arrival traveltime; (S50) Sample the candidate time points and the monitoring time points; (S60) Extract a first-arrival traveltime from a time point having a sampling value close to zero