Two-step seismic diffracted wave field pre-stack separation process

Abstract

The invention discloses a two-step seismic diffracted wave field pre-stack separation process. The process comprises the following steps of 1, carrying out decompilation and preprocessing on field seismic data; 2, extracting a common offset gather on the basis of the preprocessed full-wave-field shot record; 3, separating the diffracted wave with the large inclination angle; 4, separating the diffracted waves with the small inclination angle; 5, carrying out complete diffracted wave synthesis; 6, extracting a diffracted wave shot gather or a common midpoint gather; 7, obtaining an imaging result of the diffracted wave; and 8, on the basis of the full-wave-field pre-stack time and depth migration imaging result, performing comprehensive explanation in combination with the imaging result ofthe diffracted wave. According to the method, calculation efficiency is improved and the storage space is saved without additionally increasing the data volume; moreover, noise interference such as false frequency is also avoided; meanwhile, precision of small-dip-angle diffracted wave separation under the condition of an inclined stratum or a bent event is improved; the separated diffracted wavefield information is more complete, and the diffracted wave imaging result is higher in amplitude preservation.

Description

technical field [0001] The invention belongs to the technical field of oil and gas field exploration, and in particular relates to a pre-stack separation process of a two-step seismic diffraction wave field. Background technique [0002] In the process of oil and gas field exploration, it is found that the underground medium often has heterogeneity, especially in deep complex structural areas, fault and fracture development zones, and carbonate formations. Conventional reflection wave seismic exploration is based on the assumption of a uniform layered medium. Therefore, conventional reflection wave imaging results have low imaging accuracy and insufficient resolution for small-scale faults, caves, volcanic channels, and complex structural areas. During the propagation of seismic waves in heterogeneous strata, a large number of diffracted waves will be generated, and these diffracted wave fields contain rich information about the heterogeneity and discontinuity of subsurface ...

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Problems solved by technology

[0012] The purpose of the present invention is to provide a two-step process for pre-stack separation of seismic diffraction wavefields to solve the problem of failure to separate diffraction The diffracted wave field caused by the energy of the diffracted wave at the apex of the wave hyperbola with a small dip angle is incomplete, which in turn leads to the technical problem of low amplitude preservation of the diffracted wave imaging

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