Method for solving velocity reflectivity and density reflectivity

Abstract

The invention provides a method for solving velocity reflectivity and density reflectivity, comprising the following steps: performing measurement at different detection incidence angles to acquire corresponding detection parameters, and establishing a first matrix equation according to the detection parameters and a first formula; adding a loose constraint condition to the first matrix equation to obtain a second matrix equation, working out the apparent solution of S-wave velocity reflectivity, and working out the approximate solution of S-wave velocity reflectivity according to the approximate linear relationship between the apparent solution and the true solution; reorganizing the first formula to obtain a second formula, and obtaining a third matrix equation according to the detection parameters and the second formula; adding a loose constraint condition to the third matrix equation to obtain a fourth matrix equation, and working out the approximate solutions of P-wave impedance reflectivity and S-wave impedance reflectivity; and performing calculation according to the approximate solution of S-wave velocity reflectivity, the approximate solution of P-wave impedance reflectivity and the approximate solution of S-wave impedance reflectivity to obtain the approximate solution of density reflectivity and the approximate solution of P-wave velocity reflectivity. The method of the invention has the advantages of high applicability, noise resistance, high reliability, and the like.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploration, in particular to a decomposition method of velocity reflectivity and density reflectivity. Background technique [0002] As we all know, the target of oil exploration is rock with low density and high porosity, but in many cases the velocity of oil reservoir rock is high, especially the shear wave velocity, so the difference between its impedance (product of density and velocity) and surrounding rock impedance Smaller, the reflection amplitude intensity is reduced, making it difficult to detect, and the interpretation result is extremely uncertain, which may lead to misjudgment of oil layers or missed detection of oil layers. The crux of the problem comes from the fact that the matrix (Aki&Richard's equation) calculated by the velocity reflectivity (including longitudinal wave velocity reflectivity and shear wave velocity reflectivity) and density reflectivity is ill-conditioned o...

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Problems solved by technology

[0004] The disadvantage of the first method is that unless the angle is very large (60 degrees), the degree of improvement of the matrix is ​​limited, that is, the rank still tends to be 2 instead of 3, and high-angle data are not common, and even if there is, the signal-to-noise ratio is too low to be unreasonable. reliable

[0005] The disadvantage of the second method is that the more stringent constraints vary greatly, depending on time and location, and adding inappropriate constraints can lead to unreliable or even completely wrong solutions

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