A method of solidifying pore-forming coal strata containing weak structures

Abstract

The invention relates to a solidification and pore forming method for a coal rock stratum containing weak structural bodies. The solidification and pore forming method comprises the following steps that 1, a plurality of solidification holes are drilled, specifically, the solidification holes are formed according to the range of the weak structural bodies of the coal rock stratum to be solidified; 2, bacterium liquid, stationary liquid and cementing liquid are sequentially injected in the holes in a pressurization mode through grouting pipes, and calcium carbonate is induced to crystallize through a MICP in-situ grouting technology; and 3, after fractures and the weak structures around the solidification holes are solidified through the microorganism slurry, production is organized in solidification positions according to the subsequent process. On the one hand, microorganisms are adsorbed on the surfaces of pores and the fractures around the drilling holes, the calcium carbonate is effectively induced to precipitate, and the inner surface of the coal (rock) stratum is bonded and cemented, and surrounding rock with the soft characteristic is solidified and cemented to form a whole with certain mechanical properties, so that the strength of hole wall surrounding rock is strengthened; and on the other hand, the microorganism slurry is a solution or suspension liquid, the viscosity of the slurry is low, fluidity is good, permeability is strong, compared with a chemical treatment method, the limit grouting pressure is small, the solidification radius is large, and the cementation strength of the drilling hole surrounding rock can be regulated and controlled.

Description

technical field [0001] The invention relates to the field of reinforcement of coal and rock layers, in particular to a method for solidifying and forming holes in coal rock layers containing weak structures Background technique [0002] In my country's primary energy production and consumption structure, coal occupies a dominant position, accounting for about 65% of total consumption, which is much higher than the world average of 30%. With the continuous optimization of the primary energy consumption structure, although the proportion of coal continues to decline, the total amount is still growing. It is predicted that coal will still be an important support for my country's energy security in the next half century. [0003] However, due to the complex and changeable coal seam occurrence conditions in our country, many gas-containing coal seams, high coal seam gas content and coal seam gas pressure, my country's coal industry has been threatened by various natural disasters...

AI Technical Summary

Problems solved by technology

However, it is a recognized technical problem to drill long coal rocks through mudstone, structural belts and soft coal seams. During the drilling process of coal rocks with weak structures, blowout holes, hole collapse, hole blocking, drill sticking, and drill pinching often occur. The phenomenon of dynamic instability makes it difficult to form holes, the rate of hole formation is low, and the drilling depth is shallow, which seriously restricts the gas control effect of high gas and outburst mines

[0005] At present, the solutions to the instability of underground coal mine drilling mainly include aspects: one is to take measures to ensure the hole formation rate from the drilling process, such as compressed air chip removal drilling, dry-wet mixed drilling, etc.; the other is to use casing to ensure Hole forming, but the supply and transportation of casing protection materials is relatively heavy, and it is difficult to pull out in soft coal seams; the third is to improve drilling tools to improve the hole forming effect, such as using high-power drilling rigs and triangular, spiral and other special-shaped Drill pipe improves slag removal efficiency

However, none of the above methods can fundamentally solve the problem of dynamic instability in long boreholes in coal rocks with too weak structures.

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