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Nuclear magnetic resonance relaxation time and pore throat radius conversion method

A nuclear magnetic resonance and relaxation time technology, which is used in analysis by nuclear magnetic resonance, material analysis by resonance, and analysis of suspensions and porous materials. Effects of Conversion Errors

Active Publication Date: 2020-12-11
CHINA UNIV OF PETROLEUM (BEIJING) +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The first aspect of the above conversion method requires parallel sampling of two core samples. However, there will be differences in the core samples themselves, resulting in conversion errors; The state is mercury-gas two-phase, and different phase states will also convert errors; thirdly, the high-pressure mercury injection experiment itself will miss the large pore throat information and the minimum pore throat information detected by the instrument is controlled by the mercury injection pressure (such as 200MPa The maximum pressure can identify the pores of 36nm), so based on this experiment, the NMR T 2 Conversion of spectrograms to pore throat radii also produces conversion errors

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  • Nuclear magnetic resonance relaxation time and pore throat radius conversion method
  • Nuclear magnetic resonance relaxation time and pore throat radius conversion method

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Embodiment 1

[0041] refer to figure 1 , the conversion method of NMR relaxation time and pore throat radius in the embodiment of the present invention comprises the following steps:

[0042] Step S101, obtaining the nuclear magnetic resonance T before the centrifugation experiment of the core sample 2 Spectra, and NMR T after different centrifugation experiments 2 spectrum, and according to the NMR T before the centrifugation experiment 2 Spectra and NMR T after each centrifugation experiment 2 The spectrum calculates relaxation time cutoffs, resulting in multiple relaxation time cutoffs.

[0043] In the embodiment of the present invention, the core sample is a standard columnar tight sandstone core sample. The size of the core sample is 2.5cm×5cm, that is, the bottom surface diameter of the core sample is 2.5cm, and the height of the core sample is 5cm.

[0044] The temperature during the above centrifugation experiment is 2-6°C. For example, the temperature of the centrifuge can be s...

Embodiment 2

[0066] refer to figure 2 , the conversion method of NMR relaxation time and pore throat radius in the embodiment of the present invention comprises the following steps:

[0067] Step S201, performing saturated water treatment on the core sample.

[0068] In the embodiment of the present invention, the core sample is a standard columnar tight sandstone core sample, the size of the core sample is 2.5cm×5cm, that is, the bottom surface diameter of the core sample is 2.5cm, and the height of the core sample is 5cm.

[0069] The above-mentioned saturated water treatment is carried out pressurization and saturation treatment to the rock core sample, so that water can be filled in the pores of the rock core sample so as to carry out the nuclear magnetic resonance experiment. The pressure during the saturated water treatment in the embodiment of the present invention is 30Mpa, and the saturated water treatment time for 12 hours.

[0070] When the pore volume of the core sample is e...

Embodiment 3

[0101] refer to image 3 , the conversion method of NMR relaxation time and pore throat radius in the embodiment of the present invention comprises the following steps:

[0102] Step S301, after the core sample is smoothed, washed with oil, and dried, it is weighed, its volume is measured, and its gas porosity is calculated.

[0103] In the embodiment of the present invention, the core sample is a standard columnar tight sandstone core sample, the size of the core sample is 2.5cm×5cm, that is, the bottom surface diameter of the core sample is 2.5cm, and the height of the core sample is 5cm. The core sample can be selected by a coring device, and the two ends of the core sample can be ground by a cutting machine for subsequent experiments.

[0104] It should be noted that the core sample needs to be washed with oil, for example, the core sample is washed with benzene-methanol solvent to clean the crude oil and impurities in the pores of the core sample. After the oil-washed c...

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Abstract

The invention provides a nuclear magnetic resonance relaxation time and pore throat radius conversion method, and relates to the technical field of oil and gas exploration and development. The methodis used for solving a technical problem that an error is large when nuclear magnetic resonance relaxation time is converted into a pore throat radius. The conversion method comprises the following steps: obtaining a nuclear magnetic resonance T2 spectrogram of a rock core sample before a centrifugal experiment and a nuclear magnetic resonance T2 spectrogram of the rock core sample after differentcentrifugal experiments, and calculating relaxation time cut-off values according to the nuclear magnetic resonance T2 spectrogram before the centrifugal experiment and the nuclear magnetic resonanceT2 spectrograms after the centrifugal experiments to obtain the plurality of relaxation time cut-off values; calculating pore throat radius values according to the centrifugal force values in the different centrifugal experiments to obtain a plurality of pore throat radius values; and fitting the plurality of relaxation time cut-off values with the plurality of corresponding pore throat radius values, measuring the same rock core sample so that conversion errors caused by difference of the rock core samples are avoided, directly fitting the relaxation time cut-off values with the pore throat radius values, and reducing the conversion errors caused by conversion by a high-pressure mercury injection method.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploration and development, in particular to a method for converting nuclear magnetic resonance relaxation time and pore throat radius. Background technique [0002] As the field of oil and gas exploration and development in the world extends from conventional oil and gas to unconventional oil and gas, the exploration and research of unconventional oil and gas has been paid more and more attention. How to develop oil and gas resources in tight reservoirs has become a research hotspot. The pore-throat structure of tight reservoirs determines the distribution characteristics of oil, gas and water in tight reservoirs, and has a relatively important impact on the storage capacity and seepage characteristics of tight reservoirs. At the same time, the pore-throat structure is an important reservoir Physical properties have an important effect on the physical properties of tight reservoirs. Therefo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N24/08G01N15/08
CPCG01N24/081G01N15/0806G01N15/088Y02A90/30
Inventor 张帆萧汉敏姜振学唐相路刘学伟郭和坤张海琴朱林李晓慧
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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