Method for improving imaging effect of wave equation prestack depth migration

A pre-stack depth migration, wave equation technique, used in seismology, seismic signal processing, etc. for well logging

Inactive Publication Date: 2011-09-07
INST OF GEOLOGY & GEOPHYSICS CHINESE ACAD OF SCI
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Problems solved by technology

[0011] The purpose of the present invention is to provide a method for improving the imaging effect of wave equation pre-stack depth migration, using velocity analysis and velocity model direct update method to solve the mismatch between the velocity model obtained by seismic wave travel time technology and the wave migration method problem, avoiding the multiple migration calculations required for velocity modeling directly from wave equation migration; depth-angle domain residual motion correction and excision based on angle gathers that appear to be stretched and noisy can make slightly curved events Flattening makes the peaks and troughs of the event more aligned, thus better maintaining high-frequency components during the stacking process, improving the signal-to-noise ratio of imaging, and improving imaging effects

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  • Method for improving imaging effect of wave equation prestack depth migration
  • Method for improving imaging effect of wave equation prestack depth migration

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Embodiment 1

[0067] Embodiment 1: Taking the 3600-shot seismic data obtained from the 3D seismic observation in the Daqing LMD area as an example, the method for improving the imaging effect of the wave equation pre-stack depth migration is described in more detail. The specific steps are:

[0068] (1) Use multiple streamers or multiple survey lines to record the seismic signals excited by the artificial source and reflected by the underground stratum, and record them on the magnetic tape. Specifically, in the LMD area of ​​Daqing, the reflected seismic signals excited by the explosive source were obtained by means of multi-line acquisition, and recorded on the tape. The acquisition was 16 lines, bilateral observation, and the trace spacing was 40m; this time, the wave equation migration was used to directly generate the angular traces A total of 3,600 guns were used in the set method, covering 11.2 square kilometers. figure 1 It is a typical single-shot record after conventional noise su...

Embodiment 2

[0093] Embodiment 2: Using the 3600-shot seismic data obtained from the 3D seismic observation in the LMD area of ​​Daqing, a process of improving the imaging effect of the pre-stack depth migration of the wave equation is performed again. The difference between Embodiment 2 and Embodiment 1 is that the first update algorithm is used for processing.

[0094] The processing process of the first update algorithm is: in step (3), the ρ corresponding to the event at different depths is directly picked up from the velocity error spectrum according to the position of the maximum energy cluster n , and layer the initial velocity model with the velocity error pick-up position. Define a unique correction factor r for each horizon i ; then solve the following system of linear equations:

[0095]

[0096] where n is the number of velocity stratification layers obtained when interpreting horizons based on events, and z i , v i with are the thickness of the i-th layer, the average...

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Abstract

The invention provides a method for improving the imaging effect of wave equation prestack depth migration, wherein the method is used for processing seismic reflection data in seismic exploration so as to improve the application effect of the wave equation prestack depth migration. The method can be used for improving the imaging effect of the wave equation prestack depth migration by constructing the relationship of residual normal moveout between a depth domain and an angle domain and an interval velocity inversion method to directly update a migration velocity model of the wave equation prestack depth migration based on the residual normal moveout of an angle gather. Based on the relationship of residual normal moveout between the depth domain and the angle domain, the method can be used for removing the residual normal moveout, noise and stretching of a migration gather of the wave equation prestack depth migration, thereby improving the signal-to-noise ratio and resolution of a migration stack profile and improving the quality of the angle gather applied to the prestack inversion. Accordingly, the method can be used for well achieving the direct recognition of underground oil, gas or water, can be used for 2D (two-dimensional) and 3D (three-dimensional) wave equation prestack depth migration of the seismic reflection data, and has important application value for exploration of oil-gas and mineral resources.

Description

technical field [0001] The invention belongs to the technical field of reflection seismic data processing in seismic exploration, relates to wave equation pre-stack depth migration imaging in the process of seismic data processing, and is developed for practical problems encountered in the application of wave equation pre-stack depth migration methods A series of technologies to improve its application effect. Background technique [0002] In the process of seismic data processing, pre-stack migration imaging is a key link. Its main task is to "focus" the reflected seismic signals recorded on the surface to the real position of the underground reflection. When the velocity of the overlying strata of the subsurface structure changes drastically, the prestack time migration based on the pyramid travel time assumption and the prestack depth migration based on the asymptotic (ray) theory cannot correctly reflect the actual seismic wave propagation process, so it is not possible...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V1/28G01V1/36G01V1/40
Inventor 张江杰张剑锋刘礼农
Owner INST OF GEOLOGY & GEOPHYSICS CHINESE ACAD OF SCI
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