Azimuth pre-stack seismic attribution decoupling extraction method

Abstract

The invention provides an azimuth pre-stack seismic attribution decoupling extraction method. Based on a horizontal fracture heterogeneous stratum hypothesis, isotropy gradient attribute and anisotropy gradient attribute in different symmetry planes are decoupled and extracted in a concentrated manner from shale work area multi-azimuth pre-stack angle gathers. The specific steps are that: firstly fully analyzing azimuthal anisotropy characteristics caused by horizontal fractures in a shale work area, deriving two AVO approximate equations of azimuthal anisotropy caused by the horizontal fractures, extracting AVO intercept attribute and azimuth AVO gradient attribute; then, based on the extracted azimuth AVO gradient attribute, decoupling and extracting isotropy gradient attribute of the work area and anisotropy gradient attribute in different symmetry planes; and finally, using the extracted anisotropy gradient attribute in different symmetry planes to identify underground horizontal fracture positions and anisotropy intensity thereof, so as to effectively guide subsequent seismic inversion operation. The technology can enhance reliability of identifying shale horizontal fracture developing positions, and improves precision of shale reservoir prediction and fluid identification.

Description

technical field [0001] The invention belongs to the field of seismic data interpretation, and in particular relates to an azimuth pre-stack seismic attribute decoupling extraction method based on horizontal fracture heterogeneous formations. Background technique [0002] The buried depth of shale oil and gas reservoirs is shallower than that of carbonate reservoirs, and the tectonic stress of formations is relatively higher than the overlying pressure of formations, and the generated fractures will expand along the direction of the maximum principal stress and perpendicular to the minimum principal stress , so the fractures will be parallel to the bedding plane of the formation, at this time vertical fractures are rarely developed, and the horizontal fractures affected by the directional arrangement of clay mineral particles become the main factor of formation anisotropy. At the same time, horizontal fractures in different orientations cause differences in the degree of anis...

AI Technical Summary

Problems solved by technology

The basis of conventional AVO technical feature analysis is the Shuey two-term linear approximation of the Zoeppritz equation, which does not consider the influence of formation anisotropy, and the extracted AVO gradient attributes do not have azimuth information. The anisotropic gradient attributes are coupled and cannot highlight the influence of formation anisotropy. Therefore, the development of isotropic gradient and anisotropic gradient attributes for decoupling and extraction of actual formations, and horizontal fractures that comprehensively consider azimuthal anisotropy AVO technology for shale formation characteristic attribute analysis is particularly important

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