Method for shifting depth before superposition in seismic data process of undulating the earth's surface

Abstract

The invention is a prestack depth migration method for seismic data processing of a relief land surface, determining an imaging reference plane according to the highest point of a collection region, and projecting the relief land surface to a regular grid to fill a constant speed approaching to the near land surface in the relief land surface; using Fourier finite extrapolation operators of one-way wave equation to make wave field extrapolation on shot seismic source wave fields and detector received wave fields along the depth axis, and keeping the wave field between input and output datum equal to zero; imaging the extrapolated shot and detector wave field record by conjugate related imaging conditions, and stacking the related results of each frequency and processing the imaging result into a section image by routine display software, and the invention has an obvious imaging effect of complex construction on the condition of relief land surface.

Description

technical field [0001] The invention relates to the technical category of pre-stack migration imaging in the process of reflection wave seismic data processing, and is a pre-stack depth migration method for undulating surface seismic data processing. Background technique [0002] In the process of seismic exploration in areas with complex surface conditions, data collection is carried out on the undulating surface, and the geodetic datum where the data is obtained is a curved surface rather than a plane. When processing this kind of seismic data, in order to improve the imaging quality, wave equation prestack migration imaging technology needs to be used. At this time, two problems will be faced: first, the conventional wave equation prestack depth migration is based on the premise of horizontal surface Second, if the wave equation prestack depth migration method based on the horizontal surface is used for imaging, it will distort the actual shape of the subsurface structure...

AI Technical Summary

Problems solved by technology

When processing this kind of seismic data, in order to improve the imaging quality, wave equation prestack migration imaging technology needs to be used. At this time, two problems will be faced: first, the conventional wave equation prestack depth migration is based on the premise of horizontal surface conditions, which do not match the conditions of the actual undulating surface; second, if imaged with the wave equation prestack depth migration method based on a horizontal surface, it will distort the actual shape of the subsurface

The problem with this approach is that if the horizontal datum is placed above the highest point of the relief, the statics will be shifted too much; if placed at the centerline of the relief, the velocity difference between the replacement velocity and the actual subsurface medium will be large. Big

At the same time, the static correction time shift only considers the movement of the ray in the vertical direction, but does not consider the movement of the ray's horizontal component, and there is an error with the actual propagation path of the wave.

Another method in the past is to apply the pre-stack depth migration technology of the Kirchhoff integration method. The advantage is that it can flexibly deal with the conditions of the undulating surface and the irregular distribution of observation points. However, since this method is based on high-frequency ray approximation, Some wave phenomena are difficult to realize, so the imaging accuracy for complex structures is low

Images