Gas-containing-coal multistage permeability increasing method

Abstract

The invention discloses a gas-containing-coal multistage permeability increasing method. The gas-containing-coal multistage permeability increasing method includes the steps that firstly, the geological conditions of a coal seam hosting region, the coal metamorphism degree, the coal class and gas parameters are determined; secondly, according to whether a coal seam is located at a fault portion or a fold portion, different schemes are adopted to achieve first-stage permeability increasing of gas containing coal and detect the permeability increasing effect, and if a preset effect is achieved, permeability increasing of the whole coal seam is carried out with the first-stage permeability increasing scheme; thirdly, if the preset effect is not achieved, on the basis of the first-stage permeability increasing, second-stage acidification permeability increasing is carried out on the gas containing coal; finally, after the second-stage acidification permeability increasing is completed, gas extraction is carried out on the gas containing coal. According to the gas-containing-coal multistage permeability increasing method, different permeability increasing schemes are formulated according to the geology of different coal-seam hosting regions, and high pertinence is achieved; meanwhile, after multistage permeability increasing is adopted, the gas permeability of the coal seam is greatly improved, and the gas extraction rate is increased.

Description

technical field [0001] The invention relates to a gas-containing coal body anti-permeability method, in particular to a gas-containing coal body multi-stage anti-permeability method, which belongs to the technical field of anti-gas outburst safety management in coal mines. Background technique [0002] my country is the world's largest coal producer and consumer, and coal plays an important role in my country's energy structure. In recent years, my country's coal mines have invested heavily in safety, and have achieved good results. However, coal mine accidents do happen from time to time. Statistics show that mine gas accidents and roof accidents account for more than 80% of the total accidents, among which mine gas accidents are the number one killer of coal mines due to their high degree of harm, high casualty rate, and large economic losses. It can be seen that mine gas control has become the fundamental point to reduce or even eliminate gas accidents. Low permeabilit...

AI Technical Summary

Problems solved by technology

At present, the main technical methods of coal seam anti-reflection include hydraulic fracturing, high-pressure water jet reaming, hydraulic slotting, deep hole control pre-splitting blasting, etc. These methods have achieved positive results to a certain extent. However, there are also some defects, which are mainly reflected in two aspects: one is the defect in the technology itself, mainly manifested in: the persistence of pressure relief and anti-reflection effect is poor, which may lead to local stress concentration, increase the risk of protrusion, and even induce shock-protrusion composite The second is the adaptability to the coal seam, which is mainly manifested in: the gas-bearing coal body in the fold zone is characterized by high gas content, small coal particle size, low residual mechanical strength, low permeability, and strong water sensitivity. Water conservancy measures, especially hydraulic fracturing, have little effect and often fail to achieve the expected anti-permeability effect

[0004] Invention patent - a gas-liquid-solid three-phase coupling blasting method for weakening rock impact and increasing permeability (CN 103161493B), which mainly involves injecting water into the blasting hole and then blasting, so that the ordinary gas-solid two-phase blasting can be transformed into a gas-liquid-solid three-phase blasting method. Phase blasting, using water pressure blasting to generate water shock waves, jets, and secondary pressure waves to enhance the blasting effect, but this scheme has the disadvantages of slow water absorption speed of the coal seam, insufficient reduction of coal elastic energy, long water injection time and large engineering volume question

Invention patent - chemical reaction method for preventing and controlling coal seam rockburst (CN 103061766 B) injects the coal body with an alkaline solution, and uses the alkaline solution to dissolve the organic matter in the coal, thereby eliminating the impact tendency, but mainly for R o,max <0.6% low-rank coal seam, the applicability is restricted

Invention patent - a chemical plugging method for coalbed methane near the wellbore (CN 103541713 B) By injecting an appropriate amount of ethanol into the coal seam near the wellbore of the coal reservoir, the coal is extracted and extracted, so as to increase the pores of the coal reservoir for the purpose of high degree and permeability, but the cost of this option is high and the ability to use ethanol for coal extraction and extraction is limited

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