Coal seam pre-splitting method based on gas extraction

Abstract

The invention relates to a coal seam pre-splitting method based on gas extraction, which adopts a 'CO2 gas extraction device' as a tool to blast and pre-split a pre-mined coal seam, so as to increase the crack of the coal seam, drive out gas absorbed on the coal seam and extract the gas. The method particularly comprises the following steps: drilling a hole on the working surface of a pre-mined coal seam, filling CO2 gas extraction device into the drilled hole, sealing the drilled hole, detonating the CO2 gas extraction device, releasing high-pressure CO2 gas for deep-hole impact and pre-splitting of the coal seam, taking out the CO2 gas extraction device, and connecting the drilled hole with a gas extraction system to extract gas. The pre-splitting method of the invention can greatly enhance the permeability of the coal seam, promote the gas dissociation in the coal seam, and improve the underground gas extraction efficiency of the coal mine.

Description

technical field [0001] The invention belongs to the technical field of gas drainage, and relates to a method for pre-cracking coal seams before gas drainage. Background technique [0002] With the increase of coal mining depth, the amount of gas emission also increases, and the number of high-gas mines increases, especially in coal mines with poor coal seam permeability and strong gas adsorption, which makes it difficult to carry out gas extraction, and it is difficult to achieve the national gas control "16 The core standard of "draining up to standard" in the "Word Policy" poses a huge threat to the safe production of coal in my country and seriously restricts the sustainable development of the coal industry. [0003] Strengthening coal seam fissures, improving coal seam gas permeability, and then enhancing the freeness of gas in coal seams is a method to solve the "drainage difficulty" in theory. In fact, my country's current solution to the "difficult problem" of gas ext...

AI Technical Summary

Problems solved by technology

But as far as we know, the suitable explosives used in the pre-splitting blasting of deep hole explosives have not been well resolved. Although the country has invested heavily in it and included it in the plan for research, so far no results have been produced.

[0006] 2. Open flames are generated during explosive blasting, which may ignite or cause explosion of high-concentration gas, which increases safety risks when used in high-gas coal seams

However, due to the poor permeability of water in the coal body, it cannot reach the tiny cracks in the coal body at all, and can only have an effect on a few relatively large cracks. Little effect on radical improvement

In particular, the stagnant water in the coal body will have a sealing effect on its capillary micro-pores, which is not ideal for improving the freeness of gas in the coal seam, and has not been widely promoted.

[0010] 2. Cross-flow phenomenon is easy to occur during hydraulic pre-fracturing, which has a great impact on adjacent holes

Due to the limitation of coal mine geological conditions, it is difficult to drill holes. Some mines need 2-3 shifts to drill a 40-meter hole. Even so, the gas cannot be pumped out as soon as possible, which makes the extraction cost too high. have to smoke

[0013] From the current point of view, although my country has invested heavily in the research and development of coal seam pre-cracking by organizing professional teams, there has been no breakthrough at present, and it is still a key technical problem for gas control in my country's coal field.

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