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1. (WO2018076492) PULSE DETONATION CRACKING AND PERMEABILITY-INCREASING METHOD FOR COAL-BED GAS WELL

Pub. No.:    WO/2018/076492    International Application No.:    PCT/CN2016/110047
Publication Date: Fri May 04 01:59:59 CEST 2018 International Filing Date: Fri Dec 16 00:59:59 CET 2016
IPC: E21B 43/26
E21F 7/00
Applicants: CHINA UNIVERSITY OF MINING AND TECHNOLOGY
中国矿业大学
Inventors: LIN, Baiquan
林柏泉
YAN, Fazhi
闫发志
ZHANG, Xiangliang
张祥良
KONG, Jia
孔佳
LIU, Ting
刘厅
ZHU, Chuanjie
朱传杰
Title: PULSE DETONATION CRACKING AND PERMEABILITY-INCREASING METHOD FOR COAL-BED GAS WELL
Abstract:
Disclosed is a pulse detonation cracking and permeability-increasing method for a coal-bed gas well, applied to coal-bed gas well mining for a coal bed (1) with a low gas permeability. In the method, first, a positive-electrode coal-bed gas well bore (2) and a negative-electrode coal-bed gas well bore (3) are constructed from the ground to the coal bed (1). A fixed platform (4) having a positive electrode (5) installed thereon and a high voltage pulse device (7) are placed downwardly to a coal-bed pre-permeable portion in the positive-electrode coal-bed gas well bore (2) by means of a derrick (11), and another fixed platform (4) having a negative electrode (6) installed thereon is placed downwardly to a coal-bed pre-permeable portion in the negative-electrode coal-bed gas well bore (3) by means of the derrick (11). Next, the coal bed (1) between the positive electrode (5) and the negative electrode (6) is broke down with a high voltage to extract coal bed gas from the positive-electrode coal-bed gas well bore (2) and the negative-electrode coal-bed gas well bore (3). The high energy generated by a high-voltage electrical pulse directly acts on the coal bed (1) and forms a plasma channel in the coal bed (1) between the positive electrode (5) and the negative electrode (6). Huge energy passes though the plasma channel instantly, and a high temperature thermal expansive force and a shock wave formed act on the coal bed (1), effectively increasing the number of cracks in the coal bed (1) and creating a good condition for gas flow in the coal bed (1).