Undulating ground surface waveform inversion method based on auxiliary coordinate system

A waveform inversion and undulating surface technology, applied in the field of petroleum geophysical exploration, can solve problems such as the inability to completely eliminate distortion and the difficulty of accurate calculation of static corrections.

CN105549080AActive Publication Date: 2016-05-04CHINA UNIV OF PETROLEUM (EAST CHINA)
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2016-05-04

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Abstract

The invention discloses an undulating ground surface waveform inversion method based on an auxiliary coordinate system, and belongs to the technical field of geophysical prospecting for petroleum. The method comprises the steps: firstly carrying out the inversion of a curved mesh region through employing a preliminary wave waveform inversion method in an auxiliary coordinate system, so as to obtain a renewed near-surface speed; secondly carrying out speed updating through employing full-waveform inversion global speed field in the auxiliary coordinate system, so as to overcome the impact on deep speed field inversion from an inaccurate near-surface speed; and finally carrying out speed inversion from low frequency to high frequency through employing a time domain multi-scale inversion method, so as to overcome the dependency of a waveform inversion method on a preliminary speed model. The method can achieve the good inversion of a speed field of a severely undulating ground surface, and provides an accurate offset speed field for high-precision imaging method.
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Description

technical field

[0001] The invention belongs to the field of petroleum geophysical exploration, and in particular relates to an inversion method for undulating surface waveforms based on an auxiliary coordinate system. Background technique

[0002] The severe undulation of the surface has a serious impact on the acquisition and processing of seismic data. Geophysics researchers have developed a series of methods to overcome this problem. At present, there are two main strategies for processing the undulating surface: one is to correct the surface wave field, and the other is to perform depth migration imaging based on the undulating surface. However, it is difficult to calculate the static correction amount accurately under complex conditions, and the static correction cannot completely eliminate the distortion of the seismic wave field caused by the surface relief. Therefore, the depth migration imaging method directly based on the surface relief has gradually become a rese...

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Embodiment Construction

[0073] Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

[0074] A flow chart of a method for inversion of undulating surface waveforms based on an auxiliary coordinate system (such as figure 1 shown), including the following steps:

[0075] Input the initial global velocity field, conventional pre-stack shot records, fluctuation elevation and source wavelet, and establish an observation system;

[0076] Grid division is performed according to the initial global velocity field and fluctuation elevation, the grid near the surface is divided into curved grids, and the deep grid is divided into rectangular grids;

[0077] Transform the initial global velocity field to a rectangular grid in the auxiliary coordinate system;

[0078] Divide the time window for conventional pre-stack shot records, apply early-arrival wave waveform inversion to the velocity field of the curved grid area near the surface in t...