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Method for measuring content of free gas in coal bed gas

A technology for free gas and coalbed methane, which is applied in the fields of climate sustainability, analysis by nuclear magnetic resonance, water resource assessment, etc. It can solve the problem of low total gas content and achieve the effect of accurate measurement.

Active Publication Date: 2012-07-11
PETROCHINA CO LTD
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Problems solved by technology

[0006] The technical problem to be solved by the present invention is to provide a method for measuring and calculating the free gas content in coalbed methane, so as to fill in the lack of free gas measurement and calculation, and solve the problem of low total gas content caused by ignoring free gas in traditional gas content testing

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  • Method for measuring content of free gas in coal bed gas
  • Method for measuring content of free gas in coal bed gas
  • Method for measuring content of free gas in coal bed gas

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Embodiment Construction

[0016] The invention discloses a method for measuring and calculating the content of free gas in coalbed methane, which is to measure and calculate the unit mass of coal by quickly obtaining the water saturation of the fresh coal core surface through the nuclear magnetic resonance method, and back-calculating to the gas saturation in the stratum state. The volume of free gas contained in the rock.

[0017] In an embodiment of the present invention, the method mainly includes the following steps:

[0018] Collecting samples: After the coal core is brought out of the wellhead, open the core tube, take fresh block samples, and take cylindrical coal samples that are not polluted by drilling fluid;

[0019] Calculate the coal sample volume V 总 ;

[0020] Calculate the initial water volume: measure the initial porosity φ of the coal sample 0 , based on which the initial water volume is calculated;

[0021] Calculate the volume of saturated water: vacuumize the coal sample and sa...

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Abstract

The invention discloses a method for measuring the content of free gas in coal bed gas. By calculating the surface water saturation of a fresh coal core and performing back calculation to obtain water saturation in the stratum state, the volume of the free gas in a coal rock of unit mass is measured. Preferably, the method comprises the following steps of: collecting a sample, namely collecting a cylindrical coal sample which is not polluted by drilling fluid; measuring the volume Vtotal of the coal sample; measuring the volume Vwater1 of initial water; measuring the volume Vwater2 of saturated water; measuring an effective burden pressure delta p and a volume coefficient B; and according to parameter results in the preceding steps, calculating the content of the free gas. By adoption of the method, the content of the free gas can be accurately measured, so a total gas content test result is approximate to an underground true value, and great significance is provided for exploration and development of the coal bed gas.

Description

technical field [0001] The invention belongs to the technical field of coalbed gas content testing, in particular to a method for measuring and calculating free gas content in coalbed gas. Background technique [0002] CBM content refers to the amount of gas contained in a unit mass or unit volume of coal under natural conditions, and its main component is CH4 (methane). The content of coalbed methane is one of the key parameters to characterize the characteristics of coalbed methane reservoirs. Accurately obtaining the content of coalbed methane is of great significance for the exploration and development of coalbed methane resources and the prevention and control of coal mine gas disasters. [0003] The coalbed methane content includes adsorbed gas, free gas and dissolved gas, and the adsorbed gas is the main one, followed by the free gas, and the dissolved gas content is extremely low. It is generally believed that the adsorbed gas accounts for more than 90% to 95% of th...

Claims

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Application Information

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IPC IPC(8): G01N24/08
CPCY02A90/30
Inventor 孙粉锦李贵中欧阳永林邓泽陈振宏王勃庚勐杨泳曾良君
Owner PETROCHINA CO LTD
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