Ultrasonic cavitation and hydrofracture combined stimulation coalbed methane extraction method

A hydraulic fracturing and ultrasonic technology, applied in the fields of mining fluids, mining equipment, earthwork drilling, etc., can solve problems such as failure to achieve anti-penetration effect, and achieve good fracturing effect, long propagation distance, and wide practicability.

Active Publication Date: 2016-09-28
CHINA UNIV OF MINING & TECH
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Problems solved by technology

At the same time, although hydraulic fracturing measures will expand the acoustic fractures of the coal body and create many new fractures, the air permeability of the coal seam will be improved to a certain extent, but due to the influence of fracturing pressure and coal seam stress, hydraulic fracturing measures alone often fail to achieve expectations anti-reflection effect

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  • Ultrasonic cavitation and hydrofracture combined stimulation coalbed methane extraction method
  • Ultrasonic cavitation and hydrofracture combined stimulation coalbed methane extraction method
  • Ultrasonic cavitation and hydrofracture combined stimulation coalbed methane extraction method

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Embodiment Construction

[0029] The present invention will be further described below in conjunction with the accompanying drawings.

[0030] as attached figure 1 and 4 As shown in Fig. 1, the anti-permeability fracturing units are implemented sequentially in groups along the bedding direction of the coal seam in the coal seam roadway.

[0031] a. First construct a main borehole with a diameter of 110-150mm, the hole length h is 0.75-0.8 of the width H of the anti-reflection mining coal seam, and the distance from the main borehole is 20-25m, and the horizontal length of the construction is 0.7-0.8H , a monitoring borehole 9 with an aperture of 80-110mm;

[0032] b. After the drilling construction is completed, the h-shaped pressure-resistant steel pipe 2 containing the cylindrical ultrasonic transducer 5 is sent into the main borehole 1. The distance between the front end of the h-shaped pressure-resistant steel pipe 2 and the front end of the main borehole 1 is 2~ 5m, the outer diameter of the ul...

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Abstract

The invention discloses an ultrasonic cavitation and hydrofracture combined stimulation coalbed methane extraction method. A main drill hole and a monitoring drill hole are constructed in an air inlet way or an air return way of the working face at first, a steel pipe of a built-in ultrasonic transducer is sent into the main drill hole after a drill bit in the main drill hole reaches a coalbed preset target position, the main drill hole is subjected to high-pressure-resistant hole sealing through a conventional grouting method, and an ultrasonic generator is turned on to continuously emit low-frequency ultrasonic waves with the frequency being 20-25 kHz to the coalbed after hole sealing is completed; hydrofracture equipment is started in 1-2 h to conduct hydrofracture operation on the main drill hole; the power of the ultrasonic waves is kept unchanged while coalbed hydrofracture is conducted, and the frequency of the ultrasonic waves is adjusted to 30-35 kHz; and hydrofracture is stopped when water flows out of the monitoring drill hole or pressure of a water injection pump decreases suddenly, the frequency and power of the ultrasonic waves are kept unchanged at the time, ultrasonic waves are emitted to the coalbed continuously, and the ultrasonic generator is turned off in 30 min. The coalbed permeability-increase method is free of pollution, low in cost and good in effect.

Description

technical field [0001] The invention relates to an ultrasonic cavitation and hydraulic fracturing combined excitation coalbed methane extraction method, which belongs to the field of coalbed methane control in underground coal mines, and is especially suitable for anti-permeability measures of medium-high hardness and low-permeability coal seams. Background technique [0002] In recent years, with the rapid increase of coal production in my country and the increase of coal mining depth, the amount of coalbed methane gushing out continues to increase, the danger of coal and gas outburst continues to increase, and coal mine gas accidents occur frequently in my country. Coalbed methane extraction is one of the most effective measures to control coal mine gas disasters. The poor air permeability of coal seam is one of the important factors restricting the extraction of coal bed methane in my country. [0003] Ultrasonic technology is widely used in industrial electroplating, ci...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21F7/00E21B43/26E21B43/24
CPCE21B43/2405E21B43/26E21F7/00
Inventor 翟成汤宗情秦雷徐吉钊武世亮仲超孙勇于国卿
Owner CHINA UNIV OF MINING & TECH
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