A method for estimating formation equivalent quality factor based on synchrosqueezing wavelet transform

Abstract

The invention discloses a method for estimating formation equivalent quality factor based on synchronous squeeze wavelet transform, which is a quality factor extraction method based on Q compensation principle. By using the synchrosqueezing wavelet transform with extremely high time-frequency resolution and energy aggregation, the seismic data of adjacent horizons (post-stack seismic data) or adjacent seismic records (vertical seismic sections) are first transformed into the time-frequency domain, Then inverse Q filtering is performed within a certain preset range of Q value, and by calculating the mean square error between the Q-compensated result in the time-frequency domain and the reference waveform spectrum, the corresponding quality factor that satisfies the minimum mean square error is found as the best etc. The effective quality factor is used to realize the optimal estimation of the quality factor. The present invention avoids the difficulty of selecting frequency bands for estimating the quality factor by the conventional spectrum ratio method, and does not have the assumption that the source spectrum is Gaussian spectrum, etc. similar to the centroid frequency method, expands the method for estimating the quality factor, and improves the estimation accuracy of the quality factor.

Description

technical field [0001] The invention relates to the technical field of geophysical processing methods for oil and gas exploration, in particular to a method for estimating formation equivalent quality factors based on simultaneous squeeze wavelet transform. Background technique [0002] When the seismic wave propagates underground, it will be attenuated by the ground due to the inhomogeneity and anelasticity of the medium, which will lead to energy dissipation and velocity dispersion of high frequency components. This intrinsic dielectric property of attenuation that causes seismic wavelet distortion and amplitude attenuation is often expressed in terms of the quality factor Q. Q is sensitive to geological information such as lithology, porosity, saturation, and permeability, and Q estimation helps to improve the resolution of seismic data, enhance the fine details of formation characteristics, and be used as a direct hydrocarbon detection indicator, etc. [0003] Currently...

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Problems solved by technology

However, the spectral ratio method needs to select an appropriate frequency band range when calculating. The results of different frequency band ranges are very different, and at the same time it is very sensitive to noise; The peak frequency is easily affected by noise; the centroid frequency migration method is obtained under the assumption that the source spectrum is a Gaussian spectrum, but the sub-wave spectrum of the actual seismic data is usually non-Gaussian distribution, which will lead to calculation errors. It is also susceptible to noise when calculating the centroid frequency

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