A method and equipment for controlling the cavitation of top coal by pulse hydraulic fracturing

Abstract

Disclosed are a method and device for controlling top coal caving performance by means of pulse hydraulic fracturing. The device comprises a hydraulic fracturing pump set (7), a high-pressure rubber hose (8), a packer (6) and a high-pressure sealing mounting rod (5). The hydraulic fracturing pump set (7) further comprises a hydraulic fracturing high-pressure pump (7-2) and a hydraulic fracturing pulse pump (7-1). The device and method are capable of combining the advantages of the methods of pulse fracturing and conventional hydraulic fracturing, first generating a fracture network in coal by means of pulse hydraulic fracturing, and then further expanding the fracture network by using conventional high-displacement hydraulic fracturing so as to fully modify the coal structure, thus reducing top coal fragmentation, and improving top coal caving performance. The device and method may enable top coal to generate sufficient fractures to weaken the top coal, thus improving top coal caving performance and reducing the caving fragmentation of the top coal, while being convenient for construction, being safe and reliable, and reducing the waste of resources.

Description

technical field [0001] The invention relates to a method for controlling the cavitation of top coal, in particular to a method and equipment for controlling cavitation of top coal by pulse hydraulic fracturing, and belongs to the technical field of coal mining. Background technique [0002] my country's thick and extra-thick coal seam reserves and production account for more than 40% of the total coal reserves and total output. Fully mechanized top coal caving is a high-yield and efficient coal mining method for mining thick coal seams that has rapidly developed in my country. At present, fully mechanized caving Mining has become the dominant coal mining method in thick and extra-thick coal seams in my country. The basic requirement of fully mechanized caving mining is "integrity before erection and broken after erection". Due to the limitation of its technical characteristics, the mine pressure on the hard thick and extra thick coal seam or the overlying strata on the top co...

AI Technical Summary

Problems solved by technology

[0004] The deep hole pre-blasting technology, blasting and water injection combined pre-comprehensive weakening technology all involve the management and transportation of explosives and detonators, and the "one shot, three inspection system" and "three-person chain firing system" must be strictly implemented for blasting, and the safety management is complicated; A large amount of harmful gases such as CO produced instantly by large-scale blasting have a huge impact on mine ventilation safety management; for high-gas mines, blasting broken coal pillars should not be used due to the hidden danger of gas explosion induced by blasting sparks; fully mechanized mining faces are generally about 200m , deep-hole blasting is carried out in the upper and lower alleys, the drill holes need to radiate the whole area, and the drill holes are long, so a large amount of explosives, detonators and other pyrotechnics are required, and the economic cost is high; explosive blasting usually arranges dense drill holes within a certain range, Single hole control range is small

[0005] Coal seam water injection fracturing technology Since the pressure of coal seam water injection is generally around 5 MPa, the crack propagation direction of hydraulic fracturing is controlled by the three-dimensional stress field, and the cracks produced are few and sparse, and the degree of weakening of the strength of the coal body is limited, so it is impossible to form enough cracks. cracks, so the effect of breaking the top coal is not obvious

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