Bedding long drilling hole seam cutting and hole washing integral coal bed gas extraction method

Abstract

The invention provides a bedding long drilling hole seam cutting and hole washing integral coal bed gas extraction method, which belongs to the technical field of improved coal rock body permeable coal bed gas extraction method and aims at solving the technical problem to provide the bedding long drilling hole seam cutting and hole washing integral coal bed gas extraction method with the advantages that the bedding long drilling hole well wall stress is scattered, the influence range is wide, and the extraction efficiency is high. The method adopts the technical scheme that a, a bedding long drilling hole is drilled in a coal bed for coal bed gas extraction; b, drill withdrawal is carried out, high-pressure water is introduced, a drill rotates in situ, and a large vertical crack is formed on the plane vertical to the axial line of the bedding long drilling hole; c, the drill withdrawal is continuously carried out, the water pressure is reduced, the hole wall of the bedding long drilling hole is flushed, the drill is stopped after going back for a distance, and a new large vertical crack is constructed by a method in the step b; d, the step c is repeated so that a plurality of large vertical cracks are formed on the bedding long drilling hole; e, the drill is withdrawn, and the hole sealing is carried out on the bedding long drilling hole; and f, coal bed gas is extracted. The method provided by the invention has the advantages that the extraction efficiency is high, and the method is suitable for underground extraction.

Description

technical field [0001] The invention discloses a method for extracting coalbed methane integrated with bedding-long drilling, cutting seams and washing holes, and belongs to the technical field of underground methods for improving the permeability of coal and rock mass and extracting coalbed methane. Background technique [0002] As long as coal is mined, coalbed methane (gas) will gushes out. Coalbed methane (gas) is one of the main disasters that threaten the safety of coal mine production and the lives of miners. At the same time, coalbed methane is a kind of clean energy. Safe production in coal mines, environmental protection, and improvement of energy structure all have significant economic and social benefits. Within the depth of 2000m in my country, the resources of coalbed methane are about 31 trillion cubic meters, and the permeability is generally less than 1×10 -3 μm 2 , generally belong to low-permeability coal reservoirs, and coalbed methane is difficult to b...

AI Technical Summary

Problems solved by technology

This technology regards the coal and rock mass as a homogeneous rock mass, and does not consider the structural characteristics of the coal and rock mass, especially the sedimentary structure characteristics of the coal and rock mass (such as bedding and cleat) and the influence of gangue on the permeability of the coal seam.

There are generally 1 to 3 layers of gangue in coal seams in my country, and the thickness of gangue is 140 to 500mm, even up to 1m. The lateral deposition is stable and the continuity is good. Deformation, the vertical fissures produced by horizontal slit pressure relief may not be able to extend well when encountering gangue in the coal seam. At the same time, the floor of the coal seam is mudstone and has obvious expansibility. The height of the horizontal slit is generally only 20-30mm. When the width of the slot is large, with the deformation of the coal seam later, the slot will be squeezed and deformed to a certain extent under the joint action of the weight of the overlying rock and the upward force generated by the floor heave, and the permeability will be reduced. To complete the horizontal slotting, the nozzle must be oriented horizontally, which is very difficult to construct. Moreover, according to the existing public information, the horizontal slotting is to drill a hole in the coal seam first, and then use a special slotting device to use high-pressure water jets. The coal body on both sides of the drill hole is cut. If the coal seam collapses, it is difficult for the slotting device to enter again, and it is impossible to complete drilling and slotting at one time.

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