Pseudo-sonic Logging Method In Near-surface

Near-surface is the most complex,sensitive and fragile part of Earth's medium,the rational use and protection of near-surface and underground space have an irreplaceable effect on the development of human civilization.Sonic velocity logging can directly measure the P-wave velocity of the formation,it has a wide range of applications in the fields of petroleum exploration and development,geophysical prospecting and many other areas,since its high vertical resolution.However,in near surface,the characteristics and instrumental responses of sonic logging to the Quaternary sedimentary soft soil layer are significantly different from those of conventional rock layer.Normally,the record of sonic logging based on the first arrival of refracted waves cannot be obtained in a soft soil layer.In order to improve the precision of shallow seismic detection,a new pseudo-sonic logging method are studied by the arrival time information of up-hole seismic survey.Up-hole seismic survey generally includes three methods: in-well uphole survey,ground uphole survey and double-hole uphole survey.The thesis describes the method of obtaining pseudo-sonic logging based on the first arrival time information of three types of up-hole seismic survey methods,and combined with actual data,methods such as static cone penetration and S-wave logging are used to verify the accuracy of pseudo-sonic logging.According to the application experience of sonic logging,the thesis applies pseudo-sonic logging in combination with actual data,including synthetic seismograms,reflection horizon standardization,calculation of elastic parameters.The analysis proves that the pseudo-sonic logging method in near-surface is feasible and has practical significance.