Negative-pressure draw-out type coal layer gas content spot sampling method

Abstract

The invention discloses a negative-pressure draw-out type coal layer gas content spot sampling method. The spot sampling method comprises the following steps of selecting a proper coal layer testing position, arranging a drilling device for drilling, and arranging a negative-pressure draw-out type sampling device beside the drilling device; in the drilling process, conveying compressed air from the inner part of a drilling rod to the bottom of a hole to blow out drillings from a gap between a hole wall and the drilling rod; when the drilling device drills with a preset sampling depth, stopping the drilling device, and blowing away coal dust retained in the hole through the compressed air; connecting a sampling pipe of the negative pressure draw-out type sampling device with the drilling rod of the drilling device; then continuously drilling the hole, switching on the negative pressure draw-out type sampling device, and enabling fresh coal dust obtained by cutting by a drilling bit to enter a coal sample collector through the drilling bit, an inner pore of the drilling rod and the sampling pipe. According to the negative-pressure draw-out type coal layer gas content spot sampling method, the spot sampling can be realized; furthermore, the sampling time can be shortened; the sampling operation can be finished within seconds; the gas loss of a coal sample is low, and the sampling efficiency is greatly improved; the sampling and the drilling can be implemented synchronously and continuously; the spot sampling method is safe and reliable; the drilling rod does not need to quit.

Description

technical field [0001] The invention belongs to the field of coal mine gas disaster prevention and control, and in particular relates to a negative pressure extraction type fixed-point sampling method for gas content in coal seams. Background technique [0002] my country's coal and gas outburst disasters are serious. Although the "Regulations on the Prevention and Control of Coal and Gas Outbursts" have been implemented since 2009, and strict requirements have been put forward for the mining of coal and gas outburst coal seams, the situation of coal and gas outburst disaster prevention and control is still severe. For example, in 2011 In just 37 days from October 4th to November 10th, 3 major accidents occurred consecutively, resulting in 67 deaths, namely: "10.4" accident in Anping Coal Mine, Qiannan Prefecture, Guizhou Province (14 deaths), Henan Coal Chemical Coking Coal Jiulishan Mine "10.27" accident (18 people died) and the "11.10" accident at Private Village Coal Mine ...

AI Technical Summary

Problems solved by technology

[0005] (1) The sampling time is long, resulting in a large amount of gas loss during the sampling process

The gas in the coal sample is completely dissipated, the measured gas desorption rate is relatively small, and the calculated gas loss is relatively small. Moreover, since a large amount of gas has been desorbed, the residual gas amount tested in the laboratory is still relatively small, resulting in a large amount of gas content. The measured value is much smaller than the actual value, which affects the objective evaluation of the gas hazard level and the subsequent selection of reliable prevention and control measures

[0006] (2) It is difficult to achieve real fixed-point sampling. Twist drill pipe sampling is seriously mixed with drill powder, which is far from the requirements of fixed-point sampling, and it is difficult to distinguish the source of coal samples; Fixed-point sampling can be achieved, but limited by the volume of the sampling chamber, the sampling volume is limited; although the core drill bit can be used for fixed-point sampling, and the sampling volume is relatively large, the accuracy of the coal seam gas content test is affected due to the long time for pulling back the drill pipe. is not an ideal fixed-point sampling method

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