Method for Estimating Media Quality Factor Using Seismic Signal Envelope Peak Instantaneous Frequency

Abstract

The invention relates to a method for estimating the medium quality factor by utilizing the peak instantaneous frequency of the envelope of the seismic signal, which includes the following steps: 1) dividing the medium into several thin plates with the thickness of the distance between two adjacent geophones in the well; 2) for the i-th A small thin plate, use the constant phase wavelet to approach the direct wave received at its top, and determine its modulation frequency σi and energy attenuation factor δi, and calculate the ratio ηi=σi / 2πδi; 3) Calculate the travel of the seismic wave on the i-th small thin plate Time 4) Calculate the instantaneous frequency of the received signal at the upper and lower interfaces of the i-th thin plate; 5) Calculate the change Δfp(i)=fp(0)-fp(τi) of the envelope peak instantaneous frequency in the i-th small thin plate; 6 ) Substituting σi, δi, τi and fp(0)-fp(τi) into the analytical relationship between the envelope peak instantaneous frequency and the quality factor Q value to calculate the quality factor Q value of the i-th small thin plate: 7) Repeat steps From 2) to 6), calculate the quality factors of other small thin plates in turn; 8) use the quality factor Q value to predict the oil and gas of the reservoir.

Description

technical field [0001] The invention relates to a seismic survey method, in particular to a method for estimating the medium quality factor by utilizing the instantaneous frequency at the envelope peak of the seismic signal. Background technique [0002] During the process of seismic wave propagation underground, due to the viscoelasticity of the formation, the seismic wave will be absorbed, including attenuation and dispersion. The magnitude of seismic attenuation is generally measured by the quality factor Q value of the formation. The laboratory and actual data measurement results show that the quality factor Q value is related to factors such as rock properties, fluid properties and fluid saturation. Therefore, the quality factor Q value is an effective tool for reservoir identification and hydrocarbon detection. In addition, the quality factor Q value can better explain the effect of AVO (Amplitude Versus Offset, the change of amplitude with offset), improve the resol...

AI Technical Summary

Problems solved by technology

This method overcomes some disadvantages of the logarithmic spectrum ratio method, such as the need not to select a variable frequency band range, but needs to use the Hilbert transform to calculate the instantaneous frequency and the complex iterative process to match the instantaneous frequency

As we all know, the Hilbert transform is susceptible to noise, so the instantaneous frequency matching method is limited in the use of noisy seismic signals

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