A method for calculating the true adsorption amount of methane in shale based on the adsorption potential theory

A technique of theoretical calculation and adsorption potential, applied in analytical materials, instruments, etc., can solve problems such as temperature influence and no interaction, and achieve the effect of reasonable and reliable results and wide application value.

Active Publication Date: 2021-05-28
SOUTHWEST PETROLEUM UNIV
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Problems solved by technology

The difficulty of this method lies in the selection of the isothermal adsorption model. At present, the Langmuir isothermal adsorption model is the most widely used, but the Langmuir isothermal adsorption model assumes that the adsorption sites on the shale surface are evenly distributed, there is no interaction between the molecules of the adsorption phase, and it is a monolayer adsorption. assumptions are too ideal
In addition, the independent variable in the Langmuir isotherm adsorption model is only pressure, which cannot reflect the influence of temperature on adsorption.

Method used

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  • A method for calculating the true adsorption amount of methane in shale based on the adsorption potential theory
  • A method for calculating the true adsorption amount of methane in shale based on the adsorption potential theory
  • A method for calculating the true adsorption amount of methane in shale based on the adsorption potential theory

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Embodiment 1

[0083] The data used in this example come from open literature (Yu Lingjie et al., 2015), and the shale samples used come from the Longmaxi Formation in the Sichuan Basin. Excess adsorption data at °C, such as figure 1 shown.

[0084] The commonly used adsorption phase methane density value combined with the Gibbs excess adsorption capacity expression was used to correct the excess adsorption capacity data, and the corrected absolute adsorption capacity was obtained:

[0085]

[0086] In the formula, V ab is the absolute adsorption capacity, cm 3 / g,V ex Using the data of excess adsorption capacity measured by experiments; ρ ad is the methane density of the adsorbed phase, cm 3 / g; ρ g is the free phase methane density, cm 3 / g. free phase methane density ρ g Obtained directly from the chemical database of the National Institute of Standards and Technology.

[0087] Determine the methane density of the adsorption phase as 0.375g / cm 3 , 0.421g / cm 3 and 0.59g / cm ...

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Abstract

The invention discloses a method for calculating the real adsorption amount of methane in shale based on the adsorption potential theory, based on the modified D-A isothermal adsorption model, combined with the test data of the supercritical isothermal adsorption experiment, and adopting the idea of ​​cyclic iteration and optimization to solve the model The parameters and the methane density of the adsorption phase at each temperature overcome the shortcomings of the commonly used Langmuir isotherm adsorption model. The obtained model parameters and the methane density of the adsorption phase can make the adsorption potential and the volume of the adsorption phase at each temperature and pressure be on the same adsorption characteristic curve. The adsorption phase density and real adsorption capacity can well satisfy the adsorption potential theory and optimization theory, and the obtained results are more reasonable and reliable. In addition to being used to calculate the real adsorption amount of methane in shale, the invention can also be popularized to calculate the real adsorption amount of methane in adsorbents such as coal and activated carbon, and has wide application value.

Description

technical field [0001] The invention relates to the technical field of unconventional natural gas exploration and development, in particular to a method for calculating the real adsorption amount of methane in shale based on the adsorption potential theory. Background technique [0002] The adsorption data directly obtained by the isothermal adsorption experiment is the excess adsorption amount. Since the excess adsorption amount ignores the influence of the volume of the adsorption phase, the test results cannot truly reflect the adsorption capacity of shale. Especially in recent years, with the increase of test pressure in shale isothermal adsorption experiments, researchers have found that the directly measured excess adsorption data shows the characteristics of first increasing and then decreasing with the increase of pressure, and the corresponding correction work is particularly important. At present, the commonly used method is to use the density of the adsorbed phase...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N7/04
CPCG01N7/04
Inventor 刘香禺赵玉龙张烈辉谢军郑健张芮菡唐慧莹郭晶晶
Owner SOUTHWEST PETROLEUM UNIV
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