Study on near-surface survey by 3-component(3-C) shallow refraction
Duan Yun-qing1, Pi Jin-yun2, Liu Bing1, Li Fei3, Tian Hai-hong1
1. China University of Geoscience,Beijing City,100083,China;
2. Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing City,100029,China;
3. Geophysical Prospecting Company,Liaohe Petroleum Exploration Bureau
Abstract：In order to acquire accurate statics and provide accurate near-surface velocity and thickness model of P-and S-waves for multi-wave and multi-component exploration,the near-surface survey by 3-C shallow refraction on three lines has been carried out by using dynamite source.The paper carried out primary study on such technology,expounded in detail the principle using polarization analysis method for separation of P-wave from S-wave and got following knowledge: the ellipticity of hodogram of P-wave first breaks is smaller,the linear polarization property is very strong;the S-wave first breaks at near offsets is difficult to be recognized and the polarization direction of S-wave first breaks at mid-far offsets is more stable,which can represent the polarization direction of S-wave shot by dynamite source and the ellipticity of hodogram is larger.Through joint interpretation of practical data,we gave the range of P-wave velocity-to-S-wave velocity ratio in low and high velocity beds and their statics in the work area as well as a set of processing and interpretation flow of 3-C shallow refraction data.
