Drilling, jam releasing and fracturing integrated device and method for soft coal seam

Abstract

The invention provides a drilling, jam releasing and fracturing integrated device and method for a soft coal seam. According to the device, a drill rod is assembled on a drilling machine, a jet flow drill bit is installed at the outlet end of the drill rod, and the inlet end of the drill rod is connected with an outlet of a low-temperature pump; outlets of a plurality of first liquid nitrogen tanks in the first set of liquid nitrogen tank group are connected with an inlet of a low-temperature pump through a first nitrogen supply pipeline; outlets of a plurality of second liquid nitrogen tanks in the second liquid nitrogen tank group are connected with the main nitrogen supply pipeline through a second nitrogen supply pipeline; a heater is arranged at the bottom of the second liquid nitrogen tank. The method comprises the steps of determining a coal seam drilling position and an anti-reflection transformation area; arranging a drilling, jam releasing and fracturing integrated device in the rock roadway; liquid nitrogen output by the first set of liquid nitrogen tank group is pressurized by a low-temperature pump and then is conveyed into a jet flow drill bit, and formed high-speed liquid nitrogen jet flow acts on a coal seam; and blocking the inlet of the drill hole, fracturing the coal seam by using high-pressure fluid generated by liquid nitrogen phase change, and forming cracks in the coal seam. By means of the device and method, drilling, jam releasing and fracturing operation can be integrally achieved.

Description

technical field [0001] The invention belongs to the technical field of coal gas extraction and control, and in particular relates to an integrated device and method for drilling, jamming and fracturing in soft coal seams. Background technique [0002] Because the soft coal seam has many problems such as soft coal quality, poor air permeability and high gas content, safety accidents such as coal and gas outburst are prone to occur during the mining process. At present, in order to reduce mining accidents in soft coal seams, the main solution is to extract gas through boreholes to reduce gas pressure. During the drilling process, the coal seam around the drill hole is broken under the high-speed impact of the drill bit, and the gas will be released quickly, which will form a high gas gradient in the drill hole, and even cause the blowhole phenomenon. At the same time, the cement formed by the mixture of broken coal powder and water will block the drill hole, making it difficu...

AI Technical Summary

Problems solved by technology

[0004] The method is simple in steps and easy to operate, and can effectively solve problems such as easy drill sticking, low porosity rate, difficult slag removal and unsatisfactory anti-permeability effect of coal seams in the drilling process of soft coal seams.

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