Abstract：The Quaternary overburden in Hangzhou Bay area is rich in shallow biogas resource that is characteristics of shallow berried depth,broad distribution,low abundance and small scale.The 2D high-resolution seismic AVO analysis for shallow gas reservoirs where the buried depth is greater than 60m was carried out in the paper.The nature of AVO analysis is to analyze the variation of seismic reflectivity with incident angles.In order to improve the exploration effects of AVO analysis and in view of geographic,seismic-geologic conditions of work area,the following measures were adopted in field acquisition and data processing: using geometry-changed system to reduce the not shot phenomenon; ②in data processing,using first break refraction static corrections,surface-consistent residual static corrections,fine velocity analysis and true amplitude restoration,using finite difference migration for the purpose of flat horizons; ③based on ordinary processing,further using such tools as true amplitude,surface consistence and denoise processings.The fine correlation and interpretation were carried out for angle-gather sections of 7 new acquired lines in work area and many AVO anomalies were discovered in combining with integrative interpretation of AVO attributes sections.The interpreted results were consistent with gas-bearing situation reflected by non-seismic geophysical and geochemical data such as static αmethod,remote-sensing data interpretation and microbial exploration data,which showed the method presented in the paper is effective tool for detection of Quaternary shallow biogas.
