Ultra-low signal-to-noise ratio high-precision speed spectrum generation method based on matching pursuit

Abstract

The invention discloses an ultra-low signal-to-noise ratio high-precision velocity spectrum generation method based on matching pursuit. The method comprises the following steps: (1), inputting calculation parameters, the maximum frequency fmax of curvelet transformation, an effective signal curvelet domain distribution range omega, a filtering threshold percentage epsilon, a gain parameter s anda convergence coefficient alpha into a computer; (2) inputting a certain to-be-processed CMP seismic trace gather d; (3) generating a complete atom library A by utilizing the curvelet transformation parameters input in the step (1); (4) setting k to be equal to 1, setting an initial iteration result shown in the description and setting a residual error rk to be equal to d,carrying out iterative decomposition oneffective signals, reserving a curvelet coefficient in the omega within the coefficient percentage epsilon range, and reconstructing to obtain the value shownin the description, carryingout enhancement shown in the description and residual errors shown in the descriptionon the effective signals so as to calculate a high-precision speed spectrum; wherein the iteration termination condition is shown in the description, if the condition is satisfied, outputting the formula shown in the description; and (5) setting a speed calculation range v belonging to [v1, v2] and a speed interval delta v, calculating a high-precision speed spectrum Sembhi = Semb.S by utilizing calculation speed spectrum conventional hyperbolic amplitude superposition and a high-precision weighting coefficient, sa being an exponential factor, and outputting the speed spectrum Sembhi.

Description

Technical field [0001] The invention relates to the technical field of seismic exploration, in particular to a method for generating an ultra-low signal-to-noise ratio and high-precision velocity spectrum based on matching tracking. Background technique [0002] Seismic velocity analysis is a very important process in seismic data processing. The accuracy of seismic velocity directly affects the quality of seismic imaging. Accurate seismic velocity can better image difficult-to-image areas such as complex structures and low signal-to-noise ratios. Conversely, if the imaging speed deviates greatly from the true speed, it is difficult to image the seismic data under these geological conditions, which severely restricts the understanding of underground geological structures. At present, all seismic velocity analysis starts from picking up the velocity spectrum in the time domain. The velocity in the time domain is usually used as the initial velocity for the subsequent depth domain ...

AI Technical Summary

Problems solved by technology

Conventional velocity analysis methods generally use coherence measurement methods for velocity analysis, and there are also higher-precision velocity analysis methods that introduce phase information, but these methods are aimed at data with extremely low signal-to-noise ratios, such as very strong multiple waves that completely cover The marine seismic data in the sedimentary fracture zone with effective signals cannot highlight the velocity characteristics of effective signals

The most important interference wave of marine seismic data is the multiple wave. The amplitude of the multiple wave is relatively strong compared with the effective reflection energy of the middle and deep layers. When the multiple wave is not suppressed or the multiple wave cannot be suppressed, the gather velocity spectrum is often prominent. What is more important is the energy of multiple waves, and the energy of primary waves is weak or even unrecognizable

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