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Simulating device and method for diameter change rule of gas extraction borehole

A technology of aperture change and gas drainage, which is applied in the direction of applying stable tension/pressure to test the strength of materials, which can solve the problem of weak resistance to damage, intensified creep deformation, and no simulation device for the variation law of drilling hole diameter. and methods

Inactive Publication Date: 2015-07-22
HENAN POLYTECHNIC UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The reason for this analysis is that due to the rheological characteristics of gas-containing coal, the hole diameter will shrink with time after the drilling is completed. Due to the low strength of the soft coal seam, the ability to resist damage is weak, and the creep deformation is more severe. Destabilization and damage may occur in a short period of time, blocking the gas drainage channel, resulting in a rapid drop in the concentration of gas drainage; the hard coal seam has a strong ability to resist damage, and although the borehole diameter has shrunk, it is still in a stable state and does not cause blockage However, in the deep part of the well field, due to the increase of ground stress and gas pressure, the creep deformation is intensified, and instability and failure may occur
Therefore, it is of great significance to study the variation law of the hole diameter of drainage boreholes for determining a reasonable gas drainage time, optimizing the layout of drilling holes and improving the effect of gas drainage. Device and method for simulating the change law of borehole diameter

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  • Simulating device and method for diameter change rule of gas extraction borehole
  • Simulating device and method for diameter change rule of gas extraction borehole

Examples

Experimental program
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Effect test

Embodiment 1

[0025] Embodiment one: see figure 1 , figure 2 , a device for simulating the change law of borehole diameter in coal seam gas drainage, comprising a true triaxial pressure test device, an optical borehole deformation observation device, a coal fracture evolution observation device and a host 10.

[0026] The true triaxial pressure test device includes a pressure cell for placing the coal body sample, three vertical pressurization mechanisms respectively arranged on the top, front and left sides of the pressure cell on three mutually perpendicular sides, and The observation hole 21 processed in the later stage on the side of the rear part of the box, when the vertical pressure mechanism applies a constant stress to the coal body sample, the corresponding observation hole 21 and pumping hole 21 are respectively opened on the side of the rear part of the pressure box and the coal body sample. Borehole 22 is used for simulated observation; the pressure box includes a base 1, an ...

Embodiment 2

[0029] Embodiment two: see figure 1 , figure 2 , the structure of this embodiment is basically the same as that of Embodiment 1, and the similarities will not be repeated. The difference is that: each side of the coal body sample is also provided with a stress conduction layer, and each side of the described The stress conduction layer on the top includes a plurality of aluminum plates 19 arranged in a matrix, and elastic rubber tubes 20 arranged between two adjacent aluminum plates 19, and the number of rows and columns of aluminum plates 19 on each side is at least two rows , the length and width of each of the pressure plates 17 are larger than the length and width of the sides of the corresponding coal body sample 9, and the size of each side of the pressure plate 17 beyond the coal body sample 21 is larger than that of the aluminum plate 19 The thickness of the steel body is small, the aluminum plate 19 is rigid, and can carry out good stress transmission, and the rubbe...

Embodiment 3

[0030] Embodiment three: see figure 1 , figure 2 , a method for simulating using any of the aforementioned coal seam gas drainage borehole diameter variation simulation devices, comprising the following steps:

[0031] ① Coal body collection: collect coal bodies of typical geological units underground, transport them to the ground, seal them with wax, and pack them into boxes;

[0032] ② Coal body sample production: process and cut the collected coal body into a cubic coal body sample of 300mm×300mm, apply sealant evenly on the surface of the coal body sample, and the thickness of the colloid after curing is greater than 1mm;

[0033]③Fixation and stress pressurization of the coal sample: put the coal sample into the true triaxial pressure test device, and apply different stresses in various directions by adjusting the three vertical pressurization mechanisms;

[0034] ④ After the stress exerted on the coal sample is constant, an electric drill is used to open obs...

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Abstract

The invention belongs to the technical field of coal mine gas disaster prevention and control as well as coal-bed gas extraction, and discloses a simulating device and method for a diameter change rule of a gas extraction borehole. The device comprises a true triaxial pressure test device, an optical borehole deformation observation device, a coal mass crack evolution observation device and a main machine. The magnitude of stresses in different directions is changed through the true triaxial pressure test device, and the diameter change rule of coal masses with different strength at different stress states can be researched by the aid of the optical borehole deformation observation device; real-time observation and image shooting can be performed on crack evolution of coal masses around the extraction borehole through a microscope and a camera of the coal mass crack evolution observation device. The device and the method have the important significance in determination of the reasonable gas extraction time and the effective extraction radius as well as optimization of the borehole arrangement manner.

Description

technical field [0001] The invention belongs to the technical field of coal mine gas disaster prevention and coal bed gas extraction, and in particular relates to a simulation device and a simulation method for the variation rule of gas drainage borehole diameter. Background technique [0002] Pre-draining coal seam gas by drilling is the most important measure to prevent and control gas disasters. The practice of gas drainage engineering shows that the effect of gas drainage in soft and hard coal seams is very different. When the boreholes in hard coal seams are drained for more than half a year, the gas drainage concentration can still be maintained at more than 20%, while the boreholes in soft coal seams After only ten days of extraction, the concentration of gas extraction quickly decays to less than 5%. Even if the extraction time is extended, it is difficult to improve the effect of gas extraction; High-concentration gas can be extracted for a long time, and in the de...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/08
Inventor 郝富昌左伟芹赵发军孙丽娟刘明举刘彦伟邓奇根
Owner HENAN POLYTECHNIC UNIV
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