Self-pressurization coal body fracturing permeability-increasing enhanced gas extraction method based on ultrasonic waves

Abstract

The invention discloses a self-pressurization coal body fracturing permeability-increasing enhanced gas extraction method based on ultrasonic waves. The self-pressurization coal body fracturing permeability-increasing enhanced gas extraction method comprises the steps: a permeability-increasing drill hole driven in a coal seam in a high-position drainage roadway, and the permeability-increasing drill hole is sealed through two hole sealing bags and grouting; water is injected into the deepest position of the permeability-increasing drill hole through the gravity of the water, and a one-way ball valve on a water injection pipe is closed to stop water injection at the moment when the internal water pressure exceeds the gravity of the water in the water injection pipe; the ultrasonic waves are emitted through ultrasonic vibrators, the water temperature rises and vaporizes due to the loss of the ultrasonic waves transmitted in water, the pressure of the deepest position of the permeability-increasing drill hole is increased, meanwhile, the cavitation effect is generated when the ultrasonic waves are transmitted in the water, and extremely high tensile stress is formed through generation and bursting of cavitation bubbles; under the combined action of the cavitation effect and vaporization pressurization, surrounding coal is fractured to form fractures; and in the whole process, a water pump is not needed, fracturing permeability increasing can be continuously conducted on a coal body only through combination of the gravity of the water and the ultrasonic waves, therefore the gas extraction effect on the coal seam after permeability increasing is guaranteed, and energy consumption is effectively reduced.

Description

technical field [0001] The invention relates to an ultrasonic-based self-pressurized coal body fracturing and anti-reflection enhanced gas drainage method, which belongs to the technical field of coal seam anti-permeability. Background technique [0002] Hydraulic fracturing technology is a commonly used coal seam permeability enhancement method. The existing hydraulic fracturing process uses a ground high-pressure pump to squeeze high-pressure fracturing fluid into the coal seam through the wellbore. When the rate of injection of fracturing fluid exceeds the absorption capacity of the coal seam, a high pressure will be formed on the surface of the coal seam. When this pressure exceeds the fracture pressure of the coal seam surface, the coal seam will be pushed open and cracks will be generated. At this time, if the fracturing fluid is continuously squeezed into the coal seam, the cracks will continue to expand to the inside of the coal seam. Although this method can achiev...

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Problems solved by technology

Although this method can achieve the anti-permeability effect on the coal seam, there are still the following problems: First, due to the high pressure required for fracturing, it is necessary to install a high-power high-pressure pump outside the borehole, so that it needs to consume A lot of energy and will produce a lot of noise; second, hydraulic fracturing is one-time fracturing, that is, when the high-pressure pump injects fracturing fluid into the coal seam, it will perform a fracturing of the coal seam, and after the high-pressure pump stops high-pressure water injection, it will stop fracturing. fracturing process, which can not achieve continuous increase in permeability of the coal seam

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