Research on gas drainage technology and equipment of high-level directional drilling in coal mine

CCTEG Xi′an Research Institute(Group)Co., Ltd., Xi′an, 710077, China

Corresponding author’s e-mail: songyubo@cctegxian.com

Abstract

The gas overrun at the upper corners of the goaf and return air lanes has been restricting the development of China's coal mining industry. To solve the problem of over-limit gas concentration at the upper corners, the fundamental reason is to reduce the gas concentration in the "fracture zone" of the coal roof . At present, the most commonly used methods such as high extraction roadway, buried pipe extraction, and high-level drilling in the "fracture zone" gas control of the goaf have the disadvantages of excessive cost and heavy workload, and the drilling trajectory of conventional drilling rigs cannot be accurately positioned problem. Therefore,it is proposed to use high-position roof directional long drilling technology to replace traditional high-drainage roadway for gas control, and analyze the influence of directional drilling diameter, position, depth and other parameters on gas drainage efficiency. Based on the analysis of four drilling cases of the directional drilling rig ZYWL-13000DS of China Coal Science and Industry Group Chongqing Research Institute Co., Ltd. at 33 (4) 13 working face of Shuangliu Coal Mine, from the perspective of construction effect,the directional drilling is a more reasonable construction level 5-8 times the mining height above the roof is appropriate; the construction diameter should be as large as possible when conditions permit;when the drilling depth is 20m deep into the fissure zone, the pumping capacity will increase greatly, and with the construction of the mining, pumping Capabilities tend to stabilize. Compared with the traditional high-drainage road control effect, the use of directional long drilling technology for gas drainage can reduce the cost by more than 70% and shorten the effective construction period by more than 75%. It is finally verified that the use of high-directional directional long drilling technology can replace the high-drainage roadway for "fracture zone" gas drainage.