Localized phase space method of multi-offset VSP imaging

Abstract

The invention discloses a localized phase space method of multi-offset VSP imaging. The localized phase space method comprises the following steps: adopting localized phase space one-way wave continuation operator based on wave field decomposition of a Gauss-Daubechies tight frame (G-D tight frame) to carry out continuation to the wave field of upgoing wave of the VSP and the wave field of downgoing wave of the seismic source, and improving computational efficiency by means of an asymptotic expansion analytic expression of the continuation operator; in order to effectively weaken offset falseimage on an imaging section, adopting imaging conditions based on the local planar assumption; combining the information of wave number (corresponding to direction of propagation) of the continuationwave field, determining a main reflecting angle corresponding to a main incident angle based on a mirror reflection at an imaging point, executing relevant imaging to the localized planar wave and carrying out superposition. The method considers the asymptotic expansion form of the continuation operator of the localized phase space, has higher computational efficiency, adopts the imaging conditions based on the local planar assumption, also can effectively weaken the offset false image and interference noise while the calculated quantity is not increased. The imaging method is beneficial to improving the effectiveness and reliability of seismic processing and explanation, can be used for seismic signal processing in oil and gas exploration, carry out exquisite imaging to underground structure form beside a well, eliminate false anomaly and improve the precision of exploration and development in oil and gas fields.

Description

Technical field: [0001] The invention belongs to the field of seismic exploration, and relates to a seismic signal processing method in seismic exploration, in particular to a localized phase space method for multi-offset VSP imaging. Background technique: [0002] In the vertical seismic profiling (VSP) observation system of seismic exploration, the reflected wave only passes through the surface once, and the resolution of the received seismic records is high, which makes it possible to use multi-offset VSP data for imaging to finely describe the underground structure. [0003] The conventional method for prestack depth migration imaging of the upgoing wave field of multi-offset VSP data is to use similar processing methods to ground data, such as the ray method, migration imaging based on the one-way wave equation, and the wave equation inverse time offset etc. [0004] The multi-offset VSP imaging method based on the one-way wave equation generally includes two aspects: ...

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Problems solved by technology

[0014] Aiming at the problem that the conventional localized phase space wave field continuation operator has low numerical calculation efficiency and no analytical expression, the present invention adopts the asymptotic expansion analytical form of the continuation operator under the condition of satisfying the asymptotic expansion; Conventional one-way wave imaging conditions can easily cause migration artifacts on the imaging section. A method for multi-offset VSP imaging using imaging conditions based on local plane assumptions is provided. This imaging condition takes into account the propagation of the wave field at the imaging point. directionality

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