COMPREHENSIVE RECOGNITION AND ANALYSIS OF PRECUSORY ANOMALIES OF SUBSURFACE FLUID IN TANGGU NO. 18 WELL

In this paper, by fuzzy recognition method,statistical recognition method and rate recognition method respectively, the observed precusory data of escaped quantity of natural gas,the escaped oil quantity and water level have been comprehensively analyzed, the mid-term precusory anomalies before the M_s ≥ 4.5 earthquakes occurred within an epicentral distance of 500 km have been recognized.the anomalies characteristics have been comprehensively analyzed,and the corresponding empirical relationship has been obtained.According to the statistic and check result of the samples of earthquakes occurred, the mid-term or short-term earthquake-response rate can reach 80% or more.The result showed that the comparison observation of muti-items of precusors at one well caru raise the ability of comprehensive prediction of earthquakes, and can provide useful observed data for the studies of precu-sor mechanism and seismogenic process.