Omnibearing aeolotropy amplitude-preservation imaging and gather extracting method

Abstract

The invention discloses an omnibearing aeolotropy amplitude-preservation imaging and gather extracting method. According to the method, the problem of aeolotropy of fractured media is solved by introducing aeolotropy parameters in the algorithm, then, accurate aeolotropy velocity fields can be established, and excellent amplitude-preservation pre-stack position gathers can be extracted. Through the omnibearing aeolotropy amplitude-preservation migration, velocity and amplification of the aeolotropy in the fractured media can be reserved and disclosed. Fracture recognition based on VVAZ inversion can be achieved by utilizing the aeolotropy velocity fields, fracture recognition based on AVAZ inversion can be achieved by extracting the gathers in the amplitude-preservation pre-stack positions, and then more accurate and more reliable fracture information can be combined through combination of the fracture recognition based on the VVAZ inversion and the fracture recognition based on the AVAZ inversion.

Description

technical field [0001] The invention belongs to the field of petroleum exploration, and relates to an omnidirectional anisotropic amplitude-preserving imaging and gathering method, which mainly serves for fracture anisotropy analysis and inversion. Background technique [0002] Fractured reservoirs account for about one-third of the world's oil and gas reservoirs, and fractures often develop in carbonate rocks, sandy mudstones, volcanic rocks, and metamorphic rocks. Fractures are not only storage spaces for oil and gas, but also fluid migration channels. Therefore, predicting the development and distribution of fractures is of great significance for searching for oil and gas. For a single group of fractured media vertically arranged, the physical properties such as the velocity and amplitude of seismic waves will change with the change of azimuth angle, and these laws provide a way to detect fractures. Therefore, whether the velocity and amplitude anisotropy characteristic...

AI Technical Summary

Problems solved by technology

The current isotropic migration or azimuth migration methods commonly used in industry are not suitable for this type of medium. These methods cannot establish an accurate anisotropic velocity field, nor can they extract fully amplitude-preserved pre-stack azimuth gathers.

Therefore, neither the velocity anisotropy nor the amplitude anisotropy can be well maintained, so that the fracture information cannot be predicted accurately enough.

The conventional Kirchhoff migration method cannot solve the problem of azimuthal anisotropy in fractured media. At this time, the travel time from the shot point and receiver point to the imaging point is determined by the azimuth and offset. The specific travel time is calculated in formula (5) , (6), (7) given in

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