1.School of Geosciences and Info-Physics,Central South University,Changsha 410083,China 2.Key Laboratory of Metallogenic Prediction of Nonferrous Metals,Ministry of Education,Central South University,Changsha 410083,China 3.School of Geophysics,Chengdu University of Technology,Chengdu 610059,China
Quaternary coverage causes the existence of local low velocity zone in the transverse and longitudinal direction in the near-surface area due to natural or human disturbances.It increases the travel time of effective first arrival wave in seismic imaging method and causes seismic imaging profile to lose the background of relative depth extraction about underground layer and anomalies,leading to mislead the judgement in the interpretation process.Ray tracing can simulate the characteristics of the time field in seismic imaging profile when there exists low zone in the near-surface area.To confirm the feasibility and applicability of using direct travel time to make static correction,the authors changed the offset and the depth of the object layer.The results show that the greater the offset,the more serious the distortion of object reflection layer lineups after static correction;the depth of object layer almost has no effect on the statics when the offset is constant;when the offset and the depth of object layer are constant,the greater velocity difference between low velocity zone and underground media,the greater the amount of excessive static correction.The authors used the cross-correlation method to conduct static correction.The anomaly of the profile after static correction is consistent with the drilling result.The two ways confirm the feasibility and applicability of using travel time difference to conduct static correction of seismic image profiles.
