Method for accurately calculating real adsorption quantity of methane on shale

Abstract

The invention provides a method for accurately calculating the real adsorption quantity of methane on shale. The method comprises the following steps: crushing muddy shale samples; drying in a thermostat; obtaining the change data of quality of the muddy shale samples along the gas pressure, and calculating the initial volume and quality of samples and a sample cylinder; calculating the excessive adsorption quantity of the samples under different pressures; making a plot of the quality and gas density of measured samples at high-pressure section in a rectangular Cartesian coordinate system, and fitting to obtain an analytic expression, requiring fitting R<2>=1; calculating the saturated adsorption quality and saturated adsorption phase volume of the samples, wherein the ratio of the two is density value of an adsorption phase; and correcting the excessive adsorption quantity of saturated adsorption points on an absolute line through the adsorption phase volume, and correcting the excessive adsorption quantity on front other points through adsorption phase density, thus obtaining the true adsorption quantity of methane on shale.

Description

technical field [0001] The invention relates to the technical field of geological exploration, in particular to a method for accurately calculating the real adsorption amount of methane on shale. Background technique [0002] Scholars at home and abroad mostly use the volumetric isothermal adsorption instrument when studying the adsorption performance of coal measure mudstone and shale. Accepted by foreign scholars, the latter uses a magnetic levitation balance as the main detection tool, and the test results are more accurate. [0003] Scholars at home and abroad have found that when using the volumetric method to study the isothermal adsorption characteristics of coal-measure mudstone and shale, when using the volumetric method to test the adsorption of methane on shale, the existence of the volume of the adsorption phase will reduce the volume of free gas in the sample cell. , and then affect the test results of shale adsorption capacity. However, the existence of the v...

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Problems solved by technology

This method combined with the isothermal adsorption model to optimize the adsorption phase density, the accuracy of the evaluation results of the adsorption phase density will largely depend on the applicability of the isothermal adsorption model, and the shale pore structure is complex, isothermal The applicability of the adsorption model is difficult to determine, so the evaluation results obtained by using this method need further study

[0005] In summary, previous studies on the density of adsorbed phases are still in the stage of theoretical assumptions or mathematical optimization, and have not been accurately tested from the experimental point of view. However, the research results of different scholars vary greatly, and there is no conclusion, which will definitely affect the objective evaluation of rock The ability to adsorb gas has a greater impact

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