Permeability measurement method considering rock fracture internal geometrical characteristics

Abstract

The invention belongs to the technical field of rock mechanics seepage measurement, particularly relates to a permeability measurement method considering rock fracture internal geometrical characteristics, and solves the problem that the existing method for measuring the rock fracture permeability by depending on a variation function theory has a large error, and adopts the scheme that the method comprises the following steps: 1, scanning the upper and lower surfaces of a sample fracture surface by a three-dimensional laser scanner, obtaining three-dimensional point cloud data, and obtaining the average fracture width <e> of a crack and the fracture contact rate omega; 2, calculating a variation function, and drawing a gap width variation function scatter diagram; 3, variation function fitting: taking data before a first maximum value point of a variation function scatter diagram, respectively adopting a spherical model, a Gaussian model and an index model for fitting by means of numerical processing software, and taking a fitting result with the highest fitting degree; 4, fitting a parameter base table C and a variable range a by using a variation function to obtain a three-dimensional distribution characteristic parameter CA of the gap width of the fissure; 5, combining the fracture average gap width <e>, the fracture contact rate omega and the gap three-dimensional distribution characteristic parameter CA to calculate the fracture permeability.

Description

technical field [0001] The invention belongs to the technical field of rock mechanics seepage measurement, and in particular relates to a permeability measurement method considering the internal geometric characteristics of rock fissures. Background technique [0002] There are a large number of natural cracks in the underground rock mass, which are potential seepage channels for underground fluids. Therefore, the seepage characteristics of rock mass cracks are one of the research focuses of underground engineering. The contact areas and cavities of these contact areas, the volume of the cavities and their spatial distribution jointly determine the "internal geometric characteristics" of rough fractures. The internal geometric characteristics of rock mass fractures have a decisive effect on the hydraulic properties of fractures. Therefore, It is necessary to study the internal geometric characteristics of the fracture, obtain its quantitative characterization parameters, and...

AI Technical Summary

Problems solved by technology

[0017] (1) The traditional variation function is calculating h and r * (h) value relationship curve is calculated by increasing h along a certain direction, but in fact, when the fluid flows in the crack, due to the complexity of the gap inside the crack, any direction may become its seepage direction;

[0018] (2) The data in the back section of the scatter diagram of the calculated variogram of the gap width fluctuates greatly, which does not fully conform to the common mathematical model of the variogram;

[0019] (3) The physical meaning of the parameters of the variogram of fracture voids (sill, range, and nugget value) and their influence on fluid seepage in fractures are not yet clear

Images