Method for increasing permeability in drilling holes in cold expansion and heat driving mode

Abstract

The invention discloses a method for increasing the permeability in drilling holes in a cold expansion and heat driving mode and is suitable for efficient extraction of underground coal mine gas. Firstly, the extraction drilling holes are formed in a coal bed in a staggered mode and strengthened; water is injected in the strengthened extraction drilling holes through a water injection pump, the water is refrigerated to be condensed into ice, a coal body is cracked through the volume expansion of icing of the water body, and an original crack is expanded; then, heat pipes are used for heating the drilling holes, the ice is transformed into water, and the water is discharged out of the drilling holes; lastly, the heat pipes are used for continually heating the coal body in the drilling holes to form a stable temperature field, the gas adsorption potential is obviously reduced through the heat effect, gas desorption is promoted, so that the purpose of strengthening gas extraction is achieved, the range of the single-hole effective pressure relief influence can be obviously enlarged, and the coal bed gas extraction efficiency is increased by 40% or more. The method is safe, reliable, low in cost, simple, practical and capable of saving time and labor.

Description

technical field [0001] The invention relates to a cold expansion and heat driving type coal permeability increasing method in a borehole, which is especially suitable for high-efficiency gas extraction of coal seams with high gas and low permeability in underground coal mines. Background technique [0002] The fundamental means of underground gas control in my country's coal mines is gas drainage measures based on borehole gas drainage. As my country's coal mines enter deep mining, the low permeability of coal seams has gradually become the main controlling factor restricting the efficient extraction of gas. Therefore, enhanced anti-reflection has become a key technology to improve the effect of gas drainage and realize the co-mining of deep coal and gas. At present, there are two main types of enhanced anti-reflection technologies, one is the method of cooperating with fluid machinery and fluid medium to treat coal bodies, such as hydraulic cutting, hydraulic fracturing, e...

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Problems solved by technology

Both methods can increase the air permeability of the coal seam and improve the gas drainage effect, but they still have their own limitations

When methods such as hydraulic slits and hydraulic fracturing are used, there will be water lock effect to inhibit gas analysis; when methods such as explosive explosion are used, it will take a lot of time and effort to charge the explosives, and the explosive itself is a source of danger, which also has a certain impact on the safety of underground production. the threat of

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