Method for calculating adsorption quantities of different aperture surfaces of shale organic matter

Abstract

The invention discloses a method for calculating adsorption quantities of different aperture surfaces of a shale organic matter. The method comprises the steps of (1), constructing an interlayer structure of graphene by means of graphite for establishing an organic matter model, and introducing a methane configuration into the established organic matter model; (2), performing adsorption simulation, performing energy minimizing on a molecule system, and obtaining an initial stable configuration through adjusting an atom position change; (3), calculating the number of methane molecules which arefilled in the organic matter aperture, determining a preferable adsorption position, utilizing a COMPASS force field in a full calculating process, calculating an intermolecular van der Waals attractive force, and an electrostatic potential energy between the methane and a skeleton; (4), dividing nano-holes into K units in a direction which is parallel with a hole wall surface, performing statistics on the kinds and number of the atoms in each box, and calculating a fluid density average value; and (5), calculating a Gibbs adsorption quantity. The method of the invention realizes better fitting between adsorption phase density calculation and an actual condition, thereby realizing higher precision.

Description

technical field [0001] The invention belongs to the field of shale gas exploration, and in particular relates to a method for calculating the surface adsorption amount of shale organic matter with different pore diameters. Background technique [0002] Scholars at home and abroad have found in the research on the adsorption performance of shale that when the volumetric method is used to test the adsorption of methane on shale, the existence of the adsorption phase volume will reduce the volume of free gas in the sample, thereby affecting the adsorption capacity of shale. impact on test results. However, the volumetric method ignores the volume of the adsorption phase, which will inevitably lead to a large deviation in the evaluation of the adsorption capacity of shale. [0003] In view of the above problems, scholars at home and abroad have tried to correct the influence of the volume of the adsorbed phase on the test of the adsorbed gas capacity from different angles. How...

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Problems solved by technology

[0014] The purpose of the present invention is to provide a method for calculating the surface adsorption of shale organic matter with different pore sizes, which solves the problem that the existing method cannot reflect the real adsorption of methane well, and the calculation of the adsorption phase density is consistent with the actual Better fit and higher accuracy

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