Inversion method for stratigraphic quality factor

Abstract

The invention relates to an inversion method for a stratigraphic Q-factor by use of amplitude spectrum attributes of a downlink wave of vertical seismic profile data in geophysical exploration data processing technology. First, the F-K (frequency-wave number) method is used for wavefield separation of VSP raw data to obtain the downlink wave. Then a downlink wavelet and a monitor wavelet are selected for the Fourier transform to gain an amplitude spectrum, the amplitude spectrum are subjected to polynomial fitting to obtain an equivalent Q, and a formula between the equivalent Q and the stratigraphic Q is used for inversion of the stratigraphic Q. The inversion method for the stratigraphic quality factor has a strong random anti-interference capability and can eliminate the difference of an exciton wavelet. The algorithm is simple and workload can also be greatly reduced. The inversed stratigraphic Q value is good in stability and high in accuracy.

Description

technical field [0001] The invention relates to a seismic exploration data processing technology, which is a formation quality factor inversion method which utilizes the downgoing wave amplitude spectrum attribute of vertical seismic profile (VSP) data and has good stability. Background technique [0002] With the improvement of seismic exploration accuracy requirements, high-resolution seismic data are required for detailed description of oil and gas reservoirs, and the absorption and attenuation of formations is a major factor affecting the resolution of seismic data. The absorption and attenuation of the formation is mainly manifested in the amplitude attenuation, phase distortion and lower frequency of the seismic wave during the propagation process, and the high frequency part attenuates faster than the low frequency part, and the attenuation is faster in the shallow layer than in the deep layer, which seriously reduces the resolution of seismic data. Rate. Accurately ...

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Problems solved by technology

[0006] All of the above methods have almost no application to actual data, and there is no public disclosure of how to use the downgoing wave of VSP data, and there is almost no correspondence between the inverted layer Q value and the layer velocity value of the formation, and it is impossible to evaluate the rationality of the inverted Q value

In addition, all the above methods do not consider the excitation wavelet difference caused by the excitation environment in the acquisition, which is hardly applicable and generalizable, and will inevitably affect the stability of the quality factor Q

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