Measurement method for effective extraction radius of drill hole

A technology of drainage radius and measurement method, which is applied to earthwork drilling, measurement, mining equipment, etc., can solve the problems of attenuation of gas leakage pressure value in pressure measurement drilling holes, difficulty in measuring gas pressure, etc., so as to reduce the difficulty of measurement and improve The effect of accuracy

Inactive Publication Date: 2015-02-25
CHINA UNIV OF MINING & TECH
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Problems solved by technology

The most commonly used method in coal mines is the pressure reduction method. This method needs to construct more pressure measuring boreholes, and the measurement of gas pressure is affected by many on-site factors. Large, and sometimes the leak pressure value of the piezometric borehole decays quickly

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  • Measurement method for effective extraction radius of drill hole
  • Measurement method for effective extraction radius of drill hole

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Embodiment Construction

[0018] An embodiment of the present invention will be further described below in conjunction with accompanying drawing:

[0019] The method for measuring the effective drainage radius of the borehole based on the radial stable flow field of the present invention is to measure the gas pressure of the coal seam by constructing a borehole perpendicular to the coal seam underground in the coal mine, and to measure the gas pressure of the coal seam by constructing four parallel gas drains around the borehole. Drain the borehole, and then fill the pressure measurement borehole with SF at the original gas pressure of the coal seam 6 Gas, create the measurement conditions of radial stable flow field, record the observation of SF under different spacing conditions between the drainage observation hole and the gas filling hole 6 Determine the extension range of different gas flow fields and the corresponding time; and determine the effective drainage radius at different times according ...

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Abstract

Provided is a measurement method for the effective extraction radius of a drill hole. Firstly, the drill hole perpendicular to a coal bed is formed, and the original gas pressure of the coal bed is measured. Secondly, four extraction drill holes perpendicular to the coal bed are formed around the drill hole according to the sequence from the near point to the far point, and connection extraction is performed immediately after the construction is completed. Meanwhile, the drill hole is filled with SF6 gas through a pressure gauge switch outside the pressure measurement drill hole, it is guaranteed that the gas pressure in the drill hole is the original gas pressure of the coal bed, and measurement conditions of a radial steady flow field are created. The time for observing the SF6 at different interval conditions of the extraction observation hole and a gas filling hole is recorded, and expansion ranges of different gas flow fields and the corresponding time are determined. The effective extraction radius at different time is determined according to a gas pressure distribution rule and the maximum allowance gas pressure in the flow field, and then the relation between the effective extraction radius of the drill hole and the pre-extraction time is obtained. The measurement method provides a basis for design of the extraction drill hole, and improves the effect of gas extraction of the coal bed.

Description

technical field [0001] The invention relates to a method for measuring the effective drainage radius of a borehole, and is especially suitable for measuring the effective drainage radius of a drainage borehole when coal seam gas is pre-drained underground in a coal mine, and belongs to the technical field of coal mine gas drainage and utilization. Background technique [0002] The effective drainage radius of the borehole is the basic parameter of coal seam gas drainage and an important basis for determining the spacing of drainage boreholes. Its size depends on the purpose of drilling gas drainage. If it is to prevent outburst, the coal body within the effective range of the drill hole should lose its ability to outburst; if it is to prevent gas from exceeding the limit, the gas content and gas emission in the coal body within the effective range of the drill hole should be reduced to a level that can be ventilated degree of safe discharge. Here it can be reflected by the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B47/10E21F7/00
CPCE21B49/008E21B49/087E21F7/00
Inventor 陈裕佳唐俊蒋承林李晓伟
Owner CHINA UNIV OF MINING & TECH
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