A mathematical model method for multi-scale and multi-field coupling seepage flow of carbon dioxide replacement shale gas

Abstract

The invention discloses a mathematical modeling method for multi-scale and multi-field coupling seepage flow of carbon dioxide replacement shale gas, which comprises the following steps: S1, establishing a classification mode of gas flow patterns in multi-scale shale pores and fractures; S2, establishing a multi-scale multi-field coupled seepage mathematical model for carbon dioxide replacement shale gas, specifically include a multi-scale multi-component gas multi-field coupled flow equation of shale, a shale skeleton deformation equation, a shale reservoir energy conservation equation, a physical property parameter equation under that action of a stress field and a fracture medium deformation field, and determining solution conditions; S3, CO2 replacement shale gas multi-scale multi-field coupled seepage mathematical model solution application. The invention has the advantages that: On the basis of the established classification mode of gas flow patterns in multi-scale shale pores and fractures, the invention establishes a shale matrix nanopore, a matrix nanopore and carbon dioxide replacing shale gas multi-component gas system multi-field coupling seepage mathematical model, andestablishes difference numerical models within and among the central grid blocks of the block.

Description

technical field [0001] The invention relates to a multi-scale multi-field coupled seepage mathematical modeling method for carbon dioxide replacement shale gas. Background technique [0002] Shale gas has very rich reserves in the world. According to the statistics of EIA (US Energy Information and Information Administration) in 2015: 95 shale gas basins and 137 sets of shale formations have been discovered in 42 countries in the world. The total amount of gas resources is about 1013×10 12 m 3 , the technically recoverable reserves of shale gas reached 220.69×10 12 m 3 . According to the evaluation results of the "China Shale Gas Resources Investigation Report (2014)" released by the Ministry of Land and Resources in 2015, the reserves of shale gas resources in my country are 134×10 12 m 3 , the recoverable reserves are 25×10 12 m 3 . At the same time, shale gas is a kind of unconventional natural gas with typical multi-scale pores and fractures, tight storage and s...

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Problems solved by technology

[0006] Due to the huge difference between coal rock and shale, the pore and fracture systems of coal rock and shale are also very different. Therefore, the mathematical model of carbon dioxide enhanced coalbed methane recovery seepage cannot be directly used for the simulation of carbon dioxide displacement shale gas seepage.

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