Method for correcting excessive adsorption quantity of adsorbate gas in isothermal adsorption experiment

A technology of excess adsorption and isothermal adsorption, applied in the field of shale gas exploration, to achieve objective evaluation results

Active Publication Date: 2016-10-12
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the adsorption amount of helium in shale is not absolutely zero, and a small amount of he

Method used

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  • Method for correcting excessive adsorption quantity of adsorbate gas in isothermal adsorption experiment
  • Method for correcting excessive adsorption quantity of adsorbate gas in isothermal adsorption experiment
  • Method for correcting excessive adsorption quantity of adsorbate gas in isothermal adsorption experiment

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Embodiment 1

[0029] The schematic diagram of volumetric isothermal adsorption experiment equipment is as follows: Figure 4 As shown, the volume of the reference cell is known, and the free volume in the sample cell (V free-He ), and the actual free volume corresponding to the adsorbate gas molecules (V frfree-adsorbate ) less than V free-He , the difference between the two is recorded as V free-difference ,but

[0030] V free-He =V free-adsorbate +V free-difference (a)

[0031] In the experiment, the total gas volume injected into the sample cell n total It can be obtained from the change of the pressure in the reference cell, and the excess adsorption amount can be obtained by making a difference with the amount of gas existing in the bulk phase density in the free volume:

[0032] n e x = n t o t a l ...

Embodiment 2

[0040] Due to the inability to control V during the experiment free-adsorbate Accurate measurements were made, so the accuracy of the above scheme cannot be verified. While the V in the molecular simulation process free-adsorbate Can get, also can get the exact value of excess adsorption. In order to verify the accuracy of the method of the present invention, the V in the simulation processfree-adsorbate It is artificially increased to simulate the high free volume measured by helium during the experiment. Use artificially increased V free-adsorbate represents the V during the experiment free-He . Due to the artificial adjustment of the free volume, the excess adsorption amount is lower than the real value, and the excess adsorption amount is less than 0 when the pressure exceeds 30 MPa (such as Figure 5 shown).

[0041] C below 2 h 6 Taking the adsorption curve on illite as an example, the problem of low excess adsorption caused by the free volume being higher than th...

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Abstract

The invention discloses a method for correcting excessive adsorption quantity of adsorbate gas in an isothermal adsorption experiment. The method comprises the following steps: (1) carrying out an isothermal adsorption experiment of the adsorbate gas on an adsorbate to obtain a curve between the excessive adsorption quantity of the adsorbate gas and pressure; (2) selecting at least three points with a linear relation on the curve, obtaining the gradient of a straight line expressed by the linear relation according to a least square method and recording the gradient as k; obtaining a free volume difference amount corresponding to the adsorbate gas with the unit mass according to a formula (1) and recording the free volume difference amount as Vfree-difference; (3) obtaining the corrected excessive adsorption quantity of the adsorbate gas according to a formula (2), so as to realize the correction of the excessive adsorption quantity of the adsorbate gas. In the experiment, a measurement error of the excessive adsorption quantity seriously misleads the exploration and exploitation of shale gas. The excessive adsorption quantity corrected by the method is used for evaluating shale gas resources and an evaluation result is more objective.

Description

technical field [0001] The invention relates to a method for correcting the excess adsorption amount of adsorbate gas in an isothermal adsorption experiment, belonging to the field of shale gas exploration. Background technique [0002] In shale gas reservoirs, gas mainly exists in adsorbed and free states, and a very small part is in dissolved state. Adsorbed gas occupies a high proportion, generally considered to be between 20% and 85% of the total gas content of shale. In addition, the storage mode of adsorption state will also improve the storage capacity of shale gas. Therefore, the storage mode of the adsorbed state is considered to be an important factor for the successful exploration and development of shale gas. In the experiment, the adsorbed gas content is usually tested by the volume method, but the isothermal adsorption experiment can only test the adsorbed gas content, and cannot study the adsorption mechanism. In recent years, in order to study the adsorpti...

Claims

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Application Information

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IPC IPC(8): G01N7/04
CPCG01N7/04
Inventor 陈国辉卢双舫李进步黄开展薛海涛王民田善思许晨曦
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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