Continuation imaging method suitable for cross-well seismic large-angle reflection conditions

Abstract

The invention discloses a continuation imaging method suitable for cross-well seismic large-angle reflection conditions. The continuation imaging method comprises the following steps: when a direct wave is removed, a wave field of a seismic source transversely extend towards a wave detector, and a receiving wave field of the wave detector transversely extends towards the seismic source; when the wave field of the seismic source and the receiving wave field of the wave detector extend to the same position, related imaging conditions are utilized for transverse continuation imaging; after images of all shot points are formed, the images are overlapped to obtain an imaging profile for cross-well seismic depth domain migration. The continuation imaging method has the advantages that a large angle of information dissemination is converted into a small angle in the direction of transverse continuation, so that the imaging effect of a vertical large-angle region is improved; separating an uplink reflected wave from a downlink reflected wave is not needed, so that the impact of the poor separating effect on an imaging result is avoided; not only the kinematic characteristics (such as temporal information) of cross-well seismic reflected wave data, but also the dynamic characteristics (such as amplitude information) of the cross-well seismic reflected wave data and the particularity of a cross-well seismic observation method are considered, so that the continuation imaging method is accurate in imaging and high in precision.

Description

technical field [0001] The invention belongs to the technical field of seismic data processing, and in particular relates to a continuation imaging method suitable for cross-well seismic large-angle reflection conditions. Background technique [0002] Due to the special observation method of crosswell seismic, the reflected wave imaging methods are generally divided into VSP-CDP imaging, travel time field continuation imaging and wave equation continuation migration imaging and other technologies. The VSP-CDP imaging method is a commonly employed method. The advantage of VSP-CDP imaging is that the algorithm is stable and easy to implement, but its disadvantages are also obvious. The main reason is that the method is based on the assumption of a horizontal layered constant velocity medium, so the imaging accuracy is low. The POSTMAP imaging of crosswell seismic is based on the VSP-CDP imaging results to further converge the diffracted waves. The effect is better than that o...

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Problems solved by technology

The advantage of VSP-CDP imaging is that the algorithm is stable and easy to implement, but its disadvantages are also obvious. The main reason is that the method is based on the assumption of a horizontal layered constant velocity medium, so the imaging accuracy is low

The POSTMAP imaging of crosswell seismic is based on the VSP-CDP imaging results to further converge the diffracted waves, and the effect is better than VSP-CDP, which is equivalent to the Kirchhoff integral method, but it is difficult to adapt to the strong lateral changes of the velocity field

At the same time, since crosswell seismic reflections are mainly large-angle reflections, there are a large number of wide-angle reflections exceeding the critical angle. However, the current crosswell seismic wave equation migration method adopts the idea of ​​vertical continuation for wavefield continuation imaging, and It is not suitable for cross-well seismic reflection conditions close to wide-angle. Even if a high-precision vertical wave field continuation operator is used, the imaging effect of large-angle steep-dip structures is still affected, especially near the two wells, where the vertical continuation of the one-way wave Imaging is very difficult

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