A Reservoir Parameter Inversion Method Considering the Second-Order Gradient of Elastic Impedance

Abstract

The invention relates to a reservoir parameter inversion method considering the second-order gradient of elastic impedance, which includes predicting elastic impedance according to pre-stack seismic data, using the elastic impedance inversion to predict reservoir parameters, and using the elastic impedance inversion to predict Specifically, the reservoir parameters are as follows: firstly, a simplified approximate formula of saturated fluid rock bulk modulus characterized by modified porosity and fluid bulk modulus is deduced; secondly, using the simplified approximate formula of rock bulk modulus, the layer, deduce the reflection coefficient approximate expression characterized by density, modified porosity and fluid bulk modulus, and establish the elastic impedance expression; finally, the pre-stack seismic gathers at different angles are used to predict the elastic impedance body, using the second ladder of elastic impedance degree, the inversion predicts the density, corrected porosity, and fluid bulk modulus of the reservoir. Compared with the prior art, the reservoir parameter inversion result of the present invention has higher stability and reliability.

Description

technical field [0001] The invention relates to the field of reservoir parameter calculation, in particular to a reservoir parameter inversion method considering the second-order gradient of elastic impedance. Background technique [0002] Fluid type identification and reservoir porosity prediction are important tasks in reservoir characterization. The fluid replacement model connects the elastic modulus of the rock with the mineral type, porosity, and fluid bulk modulus of the rock, laying the foundation for the calculation of porosity and fluid bulk modulus through the prediction of elastic parameters (Gassmann, 1951). [0003] To estimate the properties of oil and gas reservoirs from seismic data, geophysicists have proposed different types of reflection coefficient expressions. Aki and Richards (1980) proposed an approximate expression of the longitudinal wave reflection coefficient characterized by the velocity reflectivity of the longitudinal and shear waves; at the s...

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Problems solved by technology

However, the second-order gradient effect of seismic data is often ignored in the inversion process, which reduces the reliability of the inversion to a certain extent.

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