A kind of soft coal step-by-step hydraulic fracturing permeation increasing device and method

Abstract

The invention relates to a soft coal step-by-step zooming hydraulic fracturing anatonosis device and method, relating to the field of coal mine gas extraction. A hydraulic fracturing anatonosis deviceincludes a hole sealing device and a hydraulic fracturing device. The method contains the following steps: S1, classifying coal strength from the near to the distant according to field coal-rock massactual measurement regional tectonic distribution, coal mass joints and pore and fracture development situations, determining coal bed joints and pore and fracture development situations as well as coal strength, and forming gas extraction fracturing drill holes; S2, efficiently sealing the gas extraction fracturing drill holes by adopting a hole sealing device; and S3, carrying out step-by-stepzooming hydraulic fracturing on the gas extraction fracturing drill holes by adopting the hydraulic fracturing device. According to the device and the method which are provided by the invention, fractures in coal-rock masses can be extended to the utmost extent when being sufficiently developed, strong support is provided by follow-up efficient gas extraction, and a technical guarantee is providedfor precise gas extraction of a working surface and safe production.

Description

technical field [0001] The invention relates to the field of gas drainage in coal mines, and relates to a soft coal step-by-step hydraulic fracturing seepage increasing device and method. Background technique [0002] Since the 1990s, hydraulic fracturing has been widely promoted and applied as a high-efficiency gas drainage and gas disaster control technology. cracking technology has broad application prospects. Most of the existing hydraulic fracturing technologies use high-pressure pulses or low-pressure hydraulics to fracture the coal around the borehole. This method can achieve better results in high-strength hard coal seams; but in soft coal seams, large flow of high-pressure When water enters the fissures, it destroys the coal and rock mass around the borehole to a large extent, causing the soft coal seam to be damaged by high stress or even closed without the secondary fissures being fully developed, making it impossible to fully expand and extend further. As a res...

AI Technical Summary

Problems solved by technology

Most of the existing hydraulic fracturing technologies use high-pressure pulses or low-pressure hydraulics to fracture the coal around the borehole. This method can achieve better results in high-strength hard coal seams; but in soft coal seams, large flow of high-pressure When water enters the fissures, it destroys the coal and rock mass around the borehole to a large extent, causing the soft coal seam to be damaged by high stress or even closed without the secondary fissures being fully developed, making it impossible to fully expand and extend further. As a result, the effect of hydraulic fracturing is not significant, and even causes the danger of coal extrusion or outburst

If low-pressure hydraulic fracturing is used for soft coal seams, on the one hand, the impact range is small, it is not easy to form a pressure difference, it is impossible to achieve dynamic balance, and it is not easy to damage the coal body to expand cracks; Drainage is difficult, increasing the cost and difficulty of gas treatment

Therefore, for soft coal seams, how to effectively extend the coal rock mass gradually under the condition of fully developed fractures has become a technical bottleneck in the field application of existing hydraulic fracturing methods.

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