Test method of drill hole gas extraction effective radius

Abstract

The invention discloses a test method of a drill hole gas extraction effective radius. The test method of the drill hole gas extraction effective radius comprises the following steps: selecting a sulfur hexafluoride (SF6) gas trace method to conduct spot test, under the condition of testing different pitches, sampling and collecting the SF6 gas required time which is detected by a detection hole, establishing a module at the basis of the Darcy law based on the occurrence of coal seam condition of the detecting location, simulating the flowing condition of the SF6 gas in a gas seepage field; calculating and obtaining the required time Ti'of the SF6 gas which moves to a sampling and collecting test hole, calculating a sampling and collecting effective coefficient a; detecting the required time of the SF6 gas based on the sampling and collecting detection hole detected by the SF6 gas trace method, calculating the required time which lowers the relative distance gas pressure below an effective value, and calculating the drill hole gas extraction effective radius based on power function relation between drill hole sampling and collecting gas effective extraction effective radius r (m) and the sampling and collecting time t (d). The test method of the drill hole gas extraction effective radius adopts combination of a direct method and an indirect method, and solves the problems that a plurality of defects exist by using the direct method to detect a drill hole gas extraction radius and extraction effective index is difficult to ascertain.

Description

technical field [0001] The invention belongs to the technical field of coal mining, and in particular relates to a method for testing the effective radius of borehole gas drainage. Background technique [0002] Drainage by bed-by-bed drilling is the most commonly used drainage technical measure in coal mining working faces of high-gas mines and coal and gas outburst mines. It plays a vital role in reducing coal seam gas in the working face. The main basis for design and layout is the effective radius of drainage of boreholes. The effective radius of drainage refers to the coal seam gas pre-extraction, under the combined influence of the coal seam gas pressure gradient and the borehole drainage negative pressure, the gas in the coal body around the borehole continuously enters the borehole and is pumped away, forming a A circular-like area of ​​influence centered on the borehole. Drainage effective radius is the main factor affecting the pre-drainage effect of bedding boreh...

AI Technical Summary

Problems solved by technology

[0003] However, the currently commonly used measurement methods have large engineering quantities, complex and cumbersome processes, or cannot determine the effective range of the drilling radius.

Aiming at the disadvantages of the current test method, computer simulation is used to assist SF 6 The gas tracer method is used to test the effective radius of borehole gas drainage, which solves the defects of cumbersome testing process, low success rate and inability to accurately determine the effective range of drainage

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