Long-drilled long-hole coal seam sub-stage fracturing enhancement and gas extraction method in underground coal mines

Abstract

The invention discloses a method for segmental fracturing, anti-permeability and gas drainage of long boreholes in coal seams under coal mines. A coal mine tunnel drill or a kilometer drill is used to drill a long borehole with a length greater than 100m into the coal seam, and the tunnel is directly used. Drilling rig or 1,000-meter drilling rig run a rigid casing with a one-way valve in the long borehole to protect the hole, and install casing centralizers at regular intervals. A set volume of cement slurry is injected into the annular space between the walls for plugging and sealing; after that, a rigid fracturing tube with double packers or multiple packers is lowered into the casing to perform stage-by-stage fracturing of the coal seam or multi-stage segmental fracturing; after the segmental fracturing increases permeability, the fracturing pipe and packer are withdrawn, and after the drainage is completed, the casing of the long borehole in the coal seam is connected to the gas drainage pipeline for efficient gas drainage Pick. The method of the invention can greatly reduce the amount of roadway and drilling engineering, improve the efficiency of coal seam gas drainage, and reduce the cost of underground gas control in coal mines.

Description

technical field [0001] The invention relates to a method for segmental fracturing and gas drainage of long boreholes in underground coal seams of coal mines, which is suitable for segmental fracturing and gas extraction of long boreholes in coal seams containing gas. Background technique [0002] With the increase of mining depth of coal resources, coal and gas outbursts, gas explosions and other disasters are becoming more and more serious, seriously restricting the safe and efficient production of coal mines, and the discharge of gas into the atmosphere will also cause air pollution. However, coal seam gas is also a valuable non-renewable energy source. Coal mine gas can be used as gas fuel and carbon black if it is properly pumped, collected, neutralized and treated. [0003] At present, increasing the permeability of high-gas coal seams, improving the permeability of coal seams and the efficiency of gas extraction is an important way to control gas disasters and develop ...

AI Technical Summary

Problems solved by technology

The above-mentioned technologies have achieved good pressure relief and anti-reflection effects, but they are restricted by many factors in the field application, and there are the following main problems: the high-energy medium used in some technologies directly acts on the gas coal seam, the construction safety cannot be guaranteed, and it is easy to Induce blowholes or even gas dynamic disasters; there are common problems such as large amount of tunneling and drilling, long construction period, low efficiency, and poor economic benefits, which seriously affect the efficient mining and production of coal mines; the common problems of coal seam anti-reflection range are small and regional anti-reflection effects are poor , Long gas extraction time and low efficiency

In underground coal seam fracturing and anti-permeability enhancement in coal mines, floor tunnel drilling or drilling along the coal seam is mainly used for fracturing, and the construction work of the roadway and drilling is large; One-time fracturing, the fracturing range is small, and the degree of pressure relief and permeability enhancement of the coal seam is low; since the fracturing is only carried out at the bottom of the borehole, the fracturing borehole has not been fully enhanced in the axial direction, and the utilization of the fracturing borehole The rate is very low; for the soft medium of coal seam, long boreholes are prone to hole collapse, and casings need to be used for hole protection

[0005] In recent years, in the field of oil and gas field development, surface horizontal drilling and multi-stage fracturing technology have been developed rapidly. However, the surface fracturing technology is complex, and the fracturing equipment is bulky, weighing hundreds of tons or even thousands of tons. Underground coal mines It cannot be used in a narrow space; in addition, ground fracturing methods and parameters do not consider the impact on coal mine mining operations and gas dynamic disasters

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