Coal seam gas fracturing and mash gas driving method

Abstract

The invention relates to a coal seam gas fracturing and mash gas driving method, which comprises two stages including a hole sealing fracturing stage and a mash gas driving stage. According to the method, firstly, hole drilling construction is performed in a coal seam; then, a high-pressure rubber pipe is embedded in a drilling hole, and hole sealing is performed; any one drilling hole is selected as a fracturing drilling hole; high-pressure gas is injected into the fracturing drilling hole; the coal seam is fractured through gas pressure energy; the gas permeability of the coal seam is improved; and other drilling holes around the fracturing drilling hole are subjected to mash gas extraction when the high-pressure gas is injected into the fracturing drilling hole. Under the condition of non-ideal gas fracturing effects caused by high coal hardness or great ground stress and the like, high-pressure water can be firstly used for fracturing, and then, high-pressure gas is introduced into the hole; and meanwhile, the drilling holes around the fracturing drilling hole are subjected to mash gas extraction. The method has the advantages that the adsorption performance differences of coal bodies on the mash gas and the fracturing gas are considered; the gas fracturing effect is combined with the mash gas driving effect; the mash gas extraction efficiency can be effectively improved; the number of mash gas extraction holes is reduced; and the inhibiting effect of water on mash gas deabsorption is reduced. The method is simple; safety and reliability are realized; and the effect is good.

Description

technical field [0001] The invention relates to a gas fracturing method, in particular to a method for coal seam gas fracturing and gas driving, which is applicable to coal seam gas fracturing and gas extraction rate improvement. Background technique [0002] Compared with hydraulic fracturing, gas fracturing has less influence on the gas permeability of coal seam, and has less influence on the gas adsorption and desorption effect of coal seam. Research on coal seam gas fracturing technology provides a new way of thinking for increasing the gas permeability of coal seams and improving the gas extraction efficiency of coal seams. In a single outburst coal seam, improving the gas permeability of the coal seam and improving the efficiency of gas extraction are the key to the mining of a single outburst coal seam. At present, the methods commonly used to improve the air permeability of a single coal seam are: hydraulic fracturing and hydraulic slotting. Although both methods ha...

AI Technical Summary

Problems solved by technology

At present, the methods commonly used to improve the air permeability of a single coal seam are: hydraulic fracturing and hydraulic slotting. Although both methods have the effect of increasing the permeability of the coal seam, they both inevitably have the influence of water on the desorption of gas. At the same time, in the coal seam The residual moisture in the pores and fissures is likely to form a "water lock effect", which blocks the gas migration channel and is not conducive to gas drainage

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