Gas prediction in tight sandstones based on the rock-physics-derived seismic amplitude variation versus offset method  

作　　者：Han Jin Cai Liu Zhi-Qi Guo 

机构地区：[1]College of Geoexploration Science and Technology,Jilin University,Changchun,130026,Jilin,China

出　　处：《Petroleum Science》2024年第6期3951-3964,共14页石油科学(英文版)

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.42074153 and 42274160)。

摘　　要：Estimating gas enrichments is a key objective in exploring sweet spots within tight sandstone gas reservoirs.However,the low sensitivity of elastic parameters to gas saturations in such formations makes it a significant challenge to reliably estimate gas enrichments using seismic methods.Through rock physical modeling and reservoir parameter analyses conducted in this study,a more suitable indicator for estimating gas enrichment,termed the gas content indicator,has been proposed.This indicator is formulated based on effective fluid bulk modulus and shear modulus and demonstrates a clear positive correlation with gas content in tight sandstones.Moreover,a new seismic amplitude variation versus offset(AVO)equation is derived to directly extract reservoir properties,such as the gas content indicator and porosity,from prestack seismic data.The accuracy of this proposed AVO equation is validated through comparison with the exact solutions provided by the Zoeppritz equation.To ensure reliable estimations of reservoir properties from partial angle-stacked seismic data,the proposed AVO equation is reformulated within the elastic impedance inversion framework.The estimated gas content indicator and porosity exhibit favorable agreement with logging data,suggesting that the obtained results are suitable for reliable predictions of tight sandstones with high gas enrichments.Furthermore,the proposed methods have the potential to stimulate the advancement of other suitable inversion techniques for directly estimating reservoir properties from seismic data across various petroleum resources.

关 键 词：Gas content indicator POROSITY AVO Rock physics Tight sandstones 

分 类 号：P618.13[天文地球—矿床学] P631.4[天文地球—地质学]