Research on key technology for efficient drilling and completion well of L-shaped horizontal well of surface mining

ZHANG Yuanzhi; WANG Yi; ZHANG Jing

doi:10.13347/j.cnki.mkaq.20241491

Abstract：The L-shaped horizontal shaft of surface mining is an effective technical means to realize the corner gas control in the up-per corner of coal mining face.At present,there are problems such as difficulties in well completion and unstable extration effects in the construction process of L-shaped wells of surface mining.In order to improve the treatment effect of the upper corner and return air gas in the working face,the 1076 working face of Yangliu Coal Mine in Huaibei Mining Area was taken as the research object,and the failure law of overburden mining in Yangliu Mine was revealed by theoretical analysis and numerical simulation,the devel-opment height of the"two belts"was determined,the location of the L-shaped mining well was optimized,and the key technologies of efficient drilling and completion well of L-shaped horizontal wells of surface mining are proposed from optimized wellbore struc-ture design,three-stage trajectory optimization of horizontal sections,precise control of long horizontal section wellbore trajectory,enhanced drilling of the mining stratum and washing completion with rotating lower screen and double-layer tubing.The results show that:the maximum development height of the collapsing zone of the mining area in Yangliu Mine is about 13 m,and the max-imum development height of the fracture zone is about 40 m.The L-shaped mining horizontal well should be arranged vertically at a distance of 22-31 m from the coal seam in the roof and horizontally at a distance of 11.8-47.7 m from the return air passage on the side of the"O"ring to facilitate gas extraction;the maximum vertical ratio of the large displacement mining horizontal well is 2.50,the drilling rate of the target section is 95％,and the drilling efficiency of the horizontal section is increased by more than 20％com-pared with the conventional process.In the mining period of 1076 working face of Yangliu Coal Mine,the maximum pure amount of pressure relief gas extraction in a single well is 9.33 m3/min,the cumulative gas extraction volume reaches 1.06 million m3,the gas extraction rate of the surface well reaches 81％,and the return air gas volume fraction is less than 0.3％during the mining period,so as to ensure the safe mining of the working face.