A Sparse Regularization Method for Extracting Rock Physical Elastic Parameters

Abstract

The invention relates to a sparse regularized rock physical elastic parameter extraction method. The method includes the steps of: 1) superposing a pre-stack seismic channel set according to small, intermediate and large angle ranges to obtain elastic impedance corresponding to a small angel and an intermediate angle; 2) substituting the small angle and the intermediate angle and the corresponding elastic impedance into an elastic impedance equation to obtain an elastic impedance equation set; 3) A=[1+tan<2>theta1 -8Ksin<2>theta1 1-4Ksin<2>theta1, 1+tan<2>theta2 -8Ksin<2>theta2 1-4Ksin<2>theta2], x=[In(Vp) In(Vs) In(rho)], and b=[In(EI(theta1)) In(EI(theta2))], and the elastic impedance equation set being an underdetermined equation set: Ax=b; 4) performing operation of the underdetermined equation set to obtain a linear equation set to be solved: F(x, z, s)=[Ax-b A<T>z+s-C0 Ds-beta[mu]e]=[0 0 0]; (5) solving the linear equation set to obtain (x<k>, z<k>, s<k>)<T>; and 6) calculating according to [In(Vp) In(Vs) In(rho)]=x(k) to obtain elastic parameter longitudinal wave velocity Vp, transverse wave velocity Vs and density rho. The sparse regularized elastic parameter extraction method provided by the invention can accurately extract elastic parameters only by using elastic impedance data obtained by data of the seismic channel set of the small angle and the intermediate angle, and can be widely applied to an extraction method of rock physical elastic parameters.

Description

technical field [0001] The invention relates to a method for extracting rock physical elastic parameters, in particular to a method for extracting rock physical elastic parameters with sparse regularization. Background technique [0002] Rock physical elastic parameters are the link between seismic data and reservoir parameters. Fluid changes in rock pores have a great influence on rock elastic properties. Quantitatively determining the relationship between fluid-bearing rocks and elastic parameters can improve the reliability and accuracy of seismic reservoir prediction and oil and gas detection. Elastic parameters can be roughly divided into three categories: the first category is basic elastic parameters, which can be obtained through laboratory measurement, including longitudinal wave velocity, shear wave velocity and density; the second category is extended elastic parameters, which are generally It is difficult to measure directly, but it is calculated by using the fi...

AI Technical Summary

Problems solved by technology

At present, as the depth of the target layer of oil and gas exploration increases, it is difficult to obtain large-angle data due to the limitation of seismic acquisition offset; in addition, some complex lithology oil and gas reservoirs, such as thin interbedded sandstone or carbonate oil and gas Tibet, the signal-to-noise ratio of large-angle seismic data is relatively low

If the data of large angles cannot be obtained, then the equation (2) is an "underdetermined" equation, which cannot be solved by conventional methods

If the signal-to-noise ratio of large-angle data is low, although the requirements of equation group (2) are met, the error of the extracted elastic parameters will be large

Images