The prediction accuracy of formation pressure is low when estimating effective pressure by obtaining vertical overburden pressure and pore pressure,due to the low accuracy of compaction curves fitted by acoustic travel time differences.The rock physical method only stays in the experimental stage or relies on an empirical model,failing to accurately predict the effective pressure in theory.The pore space stiffness theory provides a new approach for rock physical modeling considering pressure factors,but the study of effective pressure only remains in the stage of rock physical modeling and lacks methods to directly and stably predict effective pressure from seismic data.To predict effective pressure directly from seismic data,this paper proposes a method using pre-stack AVO inversion to predict effective pressure of sandstone reservoirs.Firstly,assuming that the elastic modulus ratio of a dry rock skeleton is constant,the rock physical relationship between shear modulus and effec-tive pressure is established based on the pore space stiffness theory.Secondly,the linear transformation rela-tionship between elastic parameters and physical property parameters is obtained by using Taylor expansion.Thirdly,the reflection coefficient equations of effective pressure,porosity,fluid modulus,matrix shear modulus and density are formulated,and a pre-stack seismic inversion method based on the Bayesian theory is constructed.Model testing and practical data applications show that the proposed method can stably predict the effective pressure in formations even with a low signal-to-noise ratio.
关键词
干岩石/孔隙空间刚度理论/弹性参数/物性参数/泰勒展开/贝叶斯估计
Key words
dry rock/pore space stiffness theory/elastic parameter/physical property parameter/Taylor expan-sion/Bayesian estimation
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