Self-adaption surface wave attenuation method

Abstract

The invention provides a self-adaption surface wave attenuation method and belongs to the field of oil geophysical prospecting. The self-adaption surface wave attenuation method firstly conducts lowpass filtering on seismic record to obtain dominated records of the surface wave, and then uses Hilbert conversion to convert the records into analytic signals and uses an envelope amplitude difference theory to seek an optimized apparent velocity of each sampling point, and then chooses a space-time window in the sampling point along the optimized apparent velocity and uses the singular value decomposition to choose the preceding one or two maximum singular value to reconstruct space-time signals, and only the current amplitude value of the sampling point can be saved, and a surface wave model can be formed after procedures are completed one by one. Then, matched filtering between the surface wave model and original records is conducted to further revise a wave shape difference of the surface wave model. Lastly, the surface wave model is substracted from the original records and final results are obtained. The self-adaption surface wave attenuation method achieves the accurate positioning of each surface wave direction, so that vertical and horizontal amplitude changes of the surface wave in the seismic records can be overcome to a certain extent, so the self-adaption surface wave attenuation method has a adaptivity.

Description

technical field [0001] The invention belongs to the field of petroleum geophysical exploration, and in particular relates to an adaptive surface wave attenuation method. Background technique [0002] In seismic exploration, surface waves are usually very strong interference waves, which exist in seismic records and will greatly reduce the signal-to-noise ratio of the data, especially in seismic records in complex areas, where surface waves appear in more complex forms, which are of great importance to the follow-up of data. Handling is very unfavorable. Therefore, it is very necessary to study the surface wave elimination and suppression methods of seismic records in complex areas. [0003] When collecting in the field, the combination method is often used to suppress the surface wave. It uses the directional characteristics of the surface wave to place several geophones together in a certain way, so that the surface wave has a certain time difference, and the reflected wav...

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Problems solved by technology

[0005] However, these processing methods have the following deficiencies: (1) It will affect the reflected wave part that does not coincide with the surface wave in time. For example, τ-p filtering, median filtering, and K-L transformation only consider the directional characteristics of the surface wave. When the surface and underground structures are complex, the apparent velocity difference between the surface wave and some effective reflected waves is not large. Considering the frequency band characteristics, it will also affect the low-frequency range of the effective signal that does not coincide with the surface wave in time; (2) It is not suitable for surface wave elimination and suppression of seismic records in complex areas

Therefore, in the above method, the elimination and suppression of surface waves based on their linear features will produce errors

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