A Calculation Method of Carbon-Oxygen Ratio for Determining Remaining Oil Saturation

A calculation method and saturation technology, applied in the direction of earthwork drilling, wellbore/well components, etc., can solve the problem of low change sensitivity and achieve the effect of improving response sensitivity and reducing impact

Inactive Publication Date: 2018-12-14
CHINA UNIV OF PETROLEUM (EAST CHINA)
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Problems solved by technology

[0004] In view of the low sensitivity of the carbon-oxygen ratio calculated by the energy window method to the change of oil saturation, the present invention proposes a calculation method of the carbon-oxygen ratio for determining the remaining oil saturation, which can reduce the interference gamma to the carbon-oxygen ratio significantly improve the response sensitivity of carbon-oxygen ratio to oil saturation under low porosity conditions

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  • A Calculation Method of Carbon-Oxygen Ratio for Determining Remaining Oil Saturation
  • A Calculation Method of Carbon-Oxygen Ratio for Determining Remaining Oil Saturation
  • A Calculation Method of Carbon-Oxygen Ratio for Determining Remaining Oil Saturation

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Embodiment 1

[0034] The present invention, a kind of calculation method of carbon-oxygen ratio, such as figure 1 As shown, it specifically includes the following steps:

[0035] Step 1. Use the combination model of Gaussian function and linear function to fit the carbon and oxygen characteristic energy peaks of the measured inelastic gamma spectrum, and use the Levenberg-Marquardt method to calculate the relevant parameters. The fitting model is as follows:

[0036]

[0037] C 2 =d×x+e (2)

[0038] C=C 1 +C 2 (3)

[0039] In the formula: C 1 is the Gaussian part of the fitted energy peak; C 2 is the linear part of the fitting energy peak; a, b and c are the height, center position and standard deviation of the Gaussian part respectively; d and e are the first-order coefficient and constant coefficient of the linear part respectively; C is the measured inelastic gamma energy spectrum Trace count; x is the energy corresponding to the trace site, the unit is MeV, and the characteri...

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Abstract

The invention discloses a carbon-oxygen ratio calculation method used for determining remaining oil saturation. Firstly, a Gaussian and linear dual model is used for fitting and actually measuring carbon and oxygen energy peaks of inelastic gamma-ray spectrum data, and characteristic peak fitting coefficients are obtained; then, the same fitting model is used for fitting energy peaks corresponding to carbon and oxygen standard gamma-ray spectra; the ratio of height of measurement spectrum carbon peak Gaussian components and height of standard spectrum carbon peak Gaussian components is multiplied by the total number of carbon element standard spectra, so that inelastic gamma-ray generated by a carbon element is counted; the ratio of height of measurement spectrum oxygen peak Gaussian components and height of standard spectrum oxygen peak Gaussian components is multiplied by the total number of oxygen element standard spectra, so that inelastic gamma-ray generated by an oxygen element is counted; the two numbers are divided to generate the carbon-oxygen ratio. The method reduces influences of gamma-ray generated by other elements on the carbon-oxygen ratio, and improves response sensitivity of the carbon-oxygen ratio to oil saturation.

Description

technical field [0001] The invention relates to the field of petroleum and natural gas development, in particular to a method for carbon-oxygen ratio logging for carbon-oxygen ratio logging. Background technique [0002] Carbon-oxygen ratio energy spectrum logging can quantitatively evaluate remaining oil in reservoirs under unknown salinity and formation conditions with large salinity changes by recording non-elastic scattering and captured gamma rays produced by the interaction between neutrons and formation element nuclei Saturation plays an important role in the dynamic monitoring of remaining oil distribution and enhanced oil recovery in the middle and late stages of oilfield development. At present, the main method to obtain the carbon-oxygen ratio by processing the measurement of inelastic and capture gamma ray spectra is the energy window method. [0003] The detector response energy spectrum of monoenergetic gamma rays is mainly composed of the all-energy peak and ...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B49/00
CPCE21B49/087
Inventor 刘军涛张锋张泉滢吴赫田立立王新光
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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