Method for extracting coal bed methane through down-hole bedding long borehole consecutive cave building

A technology for long drilling and coalbed methane, applied in drilling equipment and methods, earthwork drilling, drill bits, etc., can solve the problems of small hole diameter, low extraction efficiency, and small influence range, and achieve improved permeability and enhanced drainage. The effect of improving mining efficiency and avoiding hole collapse

Active Publication Date: 2013-04-24
ZHONGBEI UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The present invention aims to overcome the shortcomings of the existing coal seam long drilling holes with small diameter, small influence range and low extraction efficiency, and provides a method for underground coal seam gas extraction by making continuous caving holes with long drilling holes

Method used

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  • Method for extracting coal bed methane through down-hole bedding long borehole consecutive cave building
  • Method for extracting coal bed methane through down-hole bedding long borehole consecutive cave building
  • Method for extracting coal bed methane through down-hole bedding long borehole consecutive cave building

Examples

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Embodiment 1

[0029] Embodiment 1: A method for pre-draining coal seam gas by drilling long holes along the bed in the excavation face in series. refer to figure 1 and figure 2 Shown. In a certain area, the thickness of the pre-pumped coal seam M=6000mm in the Shanxi Formation, the length of the pre-pumped roadway is 800m, and the mechanical parameters of coal and rock are unknown. According to the formula , it can be seen that the diameter of the cave is between φ1200mm, and the distance between the caves is given by the formula The estimated distance between the caves is Between 6 and 12m, S=10m is taken now. In the middle of the working face of the pre-excavation coal seam gas drainage roadway (7), use a thousand-meter drilling rig to drill the drainage long borehole (1) in the direction of the pre-excavation roadway, and the diameter of the long borehole is φ96mm. After the drilling reaches the predetermined depth, the hydraulic-mechanical variable-diameter reaming bit while dr...

Embodiment 2

[0030] Example 2: The roadway for gas drainage in the panel area adopts the method of drilling holes parallel to the long coal seam in series to pre-drain coal seam gas, refer to image 3 The situation shown is that the thickness of the pre-pumped coal seam of the Shanxi Formation in a certain area is M=6000mm, the average thickness of the mountain cover in the pre-pumped area is 460m, and the average weight of the rock mass is 25kN / m 3 , the cohesion of the coal seam is 0.4MPa, the internal friction angle of the coal seam is 25°, by the formula

[0031] , the available cave size is about φ1400mm. In addition, the size of the hole is calculated according to the thickness M of the pre-pumped coal seam, according to the formula , it can be seen that the size of the cave is between φ1200mm, comprehensively considered, the diameter of the cave is taken as φ1300mm. Cave spacing is given by the formula , then the hole spacing is Between 6.5m and 13m, the spacing of S=10...

Embodiment 3

[0032] Example 3: The coal seam gas is pre-drained by making caving holes in series in the mining face through radioactive drilling along the coal seam. refer to Figure 4 , the coal seam gas pre-drainage system is adopted for the coal mining face by drilling holes along the coal seam. According to the thickness M of the coal seam (9) and the maximum influence range of the coal seam cave (2), the size of the gas drainage single hole coal seam cave and the drilling construction are designed. Point position (5) and the angle and spacing of drainage drilling. Then use the drilling rig to drill the drainage borehole (1) in the coal seam gas drainage roadway (7) according to the drilling design trajectory. Caves (5) are built in sequence outside the hole. After the hole is built, a drainage pipe (3) is placed at the orifice, and the gas sealing section (4) of the orifice is sealed, and the borehole drainage pipe (3) is connected to the downhole Drainage system (10) is connected, ...

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Abstract

The invention relates to a method for extracting coal bed methane through down-hole bedding long borehole consecutive cave building and a hydraulic mechanical drill with the diameter changed and enlarged while drilling. A coal bed bedding long borehole is combined with a cave building technology, and the permeability of low-permeable coal reservoirs and the coal bed borehole extraction capacity are improved. A hole is opened at 1/3 coal thickness or 1.5m upwards away from the coal heading floor on the extracting drill site coal wall of an underground coal mine along with the coal bed, the hydraulic mechanical drill with the diameter changed and enlarged while drilling performs cave building on the borehole from inside to outside successively after the borehole reaches the preset depth, and the cave diameters and distances can be calculated through formulas. Coal bed stresses around the cave are released and coal bed prior cracks are widened and lengthened after the caves are completed, tensional and shear failures occur to the coal bed, novel cracks are produced, and accordingly, the coal bed crack connectivity is increased, the permeability is improved, the coal bed methane can be depressurized and desorbed rapidly, the coal bed methane extracting efficiency is improved dramatically, and the coal bed methane extracting time is shortened.

Description

[0001] technical field [0002] The invention belongs to a method for extracting coal bed gas, in particular to a method for extracting coal bed methane by making cavitations in series with long boreholes in a well. technical background [0003] Drainage of coalbed methane by underground drilling is one of the main measures to control coal mine gas and eliminate coal and gas outburst. Through drainage, the gas content in coal seams can be reduced, the amount of gas gushing out during tunnel excavation and mining face recovery can be reduced, and the coal mine gas can be reduced. The hazards associated with gas are highlighted. The method of increasing the drainage of coalbed methane underground in coal mines is mainly by increasing the drilling density and reducing the spacing of drilling holes, such as using dense drilling; or changing the layout of coal seam drilling, such as changing from parallel drilling to cross drilling; or increasing drainage. Or increase the method...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21F7/00E21B7/28E21B10/32E21B10/60
Inventor 李建军王保玉白培康李国富毛虎平胡包生田永东韩文梅鲁博王小兵李晋
Owner ZHONGBEI UNIV
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