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Method for estimating equivalent quality factor and method for estimating stratum quality factor by using method for estimating equivalent quality factor

A quality factor, equivalent technology, applied in the field of exploration geophysics, which can solve problems such as limiting the accuracy of the applicability of the centroid frequency shift method

Active Publication Date: 2015-04-29
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the simple linear relationship between the absorption amount and the centroid frequency shift used by the conventional centroid frequency shift method is derived under the assumption that the source spectrum is a Gaussian spectrum, and the centroid frequency can only be obtained when its shape is good. The analytical relationship between the shift and absorption greatly limits the applicability of the centroid frequency shift method and the accuracy of its estimation results

Method used

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  • Method for estimating equivalent quality factor and method for estimating stratum quality factor by using method for estimating equivalent quality factor
  • Method for estimating equivalent quality factor and method for estimating stratum quality factor by using method for estimating equivalent quality factor
  • Method for estimating equivalent quality factor and method for estimating stratum quality factor by using method for estimating equivalent quality factor

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0082] Example 1. A method for estimating an equivalent quality factor, the method may further comprise the steps:

[0083] 1. Extraction of source wavelet and receiver wavelet, calculation of their amplitude spectrum and travel time between them

[0084] Step 1: Source wavelet and receiver wavelet extraction

[0085] For zero-bias VSP data, the direct wave received by the near-surface geophone can be used as the source wavelet, and the direct wave received by the far-surface geophone can be used as the receiving wavelet; in actual operation, 1.5 cycles of seismic waves can be intercepted from the take-off point wavelength as the direct arrival wave.

[0086] Step 2: Calculation of amplitude spectrum of source wavelet and receiver wavelet

[0087] The extracted source wavelet and receiver wavelet are respectively applied to the Fourier transform method to calculate the corresponding amplitude spectrum.

[0088] Step 3: Determine the travel time between source wavelet and r...

Embodiment 2

[0126] Example 2. The method for calculating the formation quality factor includes the following steps:

[0127] Step 1: Divide the medium into several thin layers with the distance between two adjacent geophones in the well as the thickness;

[0128] Step 2: Calculate the equivalent quality factor between the source point and each receiver point by using the method for estimating the medium equivalent quality factor described in any one of claims 1 to 5;

[0129] Step 3: Calculate the quality factor of each thin layer

[0130] Since the above-mentioned equivalent quality factor represents the average value of the total absorption effect corresponding to the total time of the formation that propagates from the source point to the depth of each receiver point, rather than the layer quality factor corresponding to adjacent receiver points, the relationship between the two is as follows ,

[0131] ( Σ k ...

Embodiment 3

[0137] Example 3. The method for calculating the formation quality factor includes the following steps:

[0138] Step 1: Set up geophones at the boundary points of each formation in the well;

[0139] Step 2: Calculate the equivalent quality factor between the source point and each receiver point by using the method for estimating the medium equivalent quality factor described in any one of claims 1 to 5;

[0140] Step 3: Calculate the quality factor of each layer

[0141] Since the above-mentioned equivalent quality factor represents the average value of the total absorption effect corresponding to the total time of the formation that propagates from the source point to the depth of each receiver point, rather than the layer quality factor corresponding to adjacent receiver points, the relationship between the two is as follows ,

[0142] ( Σ k = 1 i...

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Abstract

The invention discloses a method for estimating an equivalent quality factor and a method for estimating a stratum quality factor by using the method for estimating the equivalent quality factor. A binary algorithm-based center-of-mass frequency shift quality factor value Q estimating method is provided on the basis of an attenuation formula of a quality factor value Q and the definition of a center-of-mass frequency and on the basis of determining the changing monotonicity of the center-of-mass frequency along with the quality factor value Q. According to the method for estimating the equivalent quality factor and the method for estimating the stratum quality factor according to the method for estimating the equivalent quality factor, the assumption that the seismic source frequency spectrum in the calculation of the quality factor value Q is a Gaussian spectrum in the conventional center-of-mass frequency shift method can be eliminated; the application range of the center-of-mass frequency shift method is expanded; the calculation precision of the quality factor value Q is improved.

Description

technical field [0001] The invention relates to the field of exploration geophysics, in particular to a method for estimating equivalent quality factors and a method for estimating formation quality factors using the method. Background technique [0002] The commonly used methods for estimating the quality factor Q value based on the attenuation characteristics of the observed data include the amplitude ratio method, the spectrum ratio method, the centroid frequency shift method, and the rise time method. The centroid frequency shift method uses the feature of wavelet extension and widening in the inelastic medium to estimate the quality factor in the frequency domain, while the rise time method directly uses the feature of wavelet extension and widening in the time domain to estimate the quality factor Q value. Compared with the former, the centroid frequency shift method has higher feasibility and stability. Compared with the amplitude ratio method and the spectrum ratio m...

Claims

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Application Information

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IPC IPC(8): G01V1/30G01V1/28
Inventor 陈雨茂王延光刘浩杰魏国华郑静静王兴谋林松辉李民龙揭景荣
Owner CHINA PETROLEUM & CHEM CORP
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