Seismic migration method and device for steep-dip stratums and fractures

Abstract

The invention provides a seismic migration method and device for steep-dip stratums and fractures. The method comprises the following steps: inputting seismic data; defining an underground horizontal reflection layer of a foundation; generating CDG (common detector gather) seismic data; carrying out layer-by-layer continuation processing on CSG (common-shot-gather) seismic data by using an amplitude-preserved Fourier finite-difference continuation operator; calculating travel time in the migration of a HV-type dual-reflected wave by using a finite-difference travel-time calculating method; carrying out layer-by-layer imaging on the HV-type dual-reflected wave; carrying out layer-by-layer continuation processing on the CDG seismic data by using the amplitude-preserved Fourier finite-difference continuation operator; calculating travel time in the migration of a VH-type dual-reflected wave by using the finite-difference travel-time calculating method; carrying out layer-by-layer imaging on the VH-type dual-reflected wave; carrying out superimposed imaging on the migration results of the HV-type dual-reflected wave and the VH-type dual-reflected wave so as to obtain an imaging result of steep-dip stratums and fractures in a target zone. The method disclosed by the invention has high calculation efficiency and can be used for obtain a high-quality imaging result of steep-dip stratums and fractures.

Description

technical field [0001] The present invention relates to a seismic data pre-stack depth migration imaging method for steep-dip strata and fractures, specifically a seismic migration method and device for steep-dip strata and fracture imaging using a double-reflection pre-stack migration method . Background technique [0002] For a long time, the problem of seismic imaging of steep-dip strata and fractures has been the bottleneck restricting the process of seismic exploration in complex structural areas, especially fracture imaging is of great significance for natural gas exploration. There are many difficulties when imaging problems. [0003] The traditional prestack depth migration method generally uses the primary reflection wave for imaging, and treats other types of seismic waves as noise. The so-called primary reflection wave such as Figure 1a As shown, the propagation path of its wave field is: shot point 10-underground reflection layer 12-receiver point 14. If one re...

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Problems solved by technology

[0005] First of all, the traditional Kirchhoff integration method and the one-way wave prestack depth migration method can only image one reflection wave due to the limitation of their own algorithms, and cannot realize the migration imaging of double reflection waves related to steep-dipping formations and fractures;

[0006] Secondly, although reverse time migration is based on the direct solution of the two-way acoustic wave equation, it can accurately image different types of seismic waves including double reflection waves, and has no dip angle limitation, but in the face of actual seismic data with steep dip angles There are still many difficulties in fracture migration imaging: because reverse time migration is full-wavefield imaging, the energy of the primary reflection wave is not suppressed, and the energy of the primary wave is much stronger than that of the double reflection wave, which will cover up the The imaging energy of double-reflection waves related to steep-dipping fractures; at the same time, reverse time migration requires a very large amount of calculation and requires extremely high accuracy of the velocity model, but reverse time migration itself cannot provide an effective velocity modeling method

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