Test method for evaluating influence of rock deformation on permeability of coal body

Abstract

The invention discloses a test method for evaluating the influence of rock deformation on coal permeability, which comprises the following steps of: applying boundary conditions for limiting displacement to a coal-rock combination sample by setting the structure of a seepage holder, and simulating the interaction condition of coal and a top plate in the coal reservoir gas development process; the method comprises the following steps: testing the deflection and coal deformation of a roof rock of a coal-rock combination under different pressure drop conditions, comparing the deflection and the coal deformation to determine the boundary condition of the coal-rock combination, and simulating the real stress state of coal and a roof in the coal reservoir gas development process and the deformation condition of the coal and the roof after stress; a basis is provided for establishing a mathematical model for finely describing the permeability of the coal reservoir, and the model is used for accurately guiding a coal reservoir gas development project, so that the time is saved, and the trial and error cost is reduced.

Description

technical field [0001] The invention relates to the technical field of coalbed methane drainage and production engineering, in particular to the research on the influence of rock deformation on the fracture permeability of coal reservoirs. Background technique [0002] Coalbed methane is an unconventional geological energy with abundant reserves in my country. The development and utilization of coalbed methane has the triple significance of resources, safety and environmental protection, and is highly valued. Although my country has achieved commercial development of coalbed methane production in some blocks, there are still problems such as low single well production and large differences. The permeability of coal reservoir is a key parameter affecting the gas production of coal seam. [0003] The method of CBM development is to drain and reduce pressure in the coal seam. When the coal seam pressure is lower than the critical desorption pressure of the adsorbed gas, the ad...

AI Technical Summary

Problems solved by technology

In actual engineering, in order to improve the economics of coal reservoir gas development, it is necessary to establish a coal reservoir permeability model to predict the gas production in advance. To establish a permeability mathematical model, the boundary conditions of the coal seam must be clarified. How to distinguish the boundary conditions caused by the change of coal seam pressure The change of constraint conditions is not clear, which brings great difficulties to establish a mathematical model that can describe the change of coal reservoir permeability in detail

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