The Deployment Of Well And The Analysis Of Effect About The Gas Extraction From Ground In Lishu Coal Mine Of Jixi Mining Area

Gas drainage is a basic means to curb the underground gas accidents, including two ways which include underground extraction and ground extraction. Drainage of surface drilling coal mine methane(CBM) due to its pre smoke for a long time, and can maximize the gas(CBM), etc,has become a new technology for coal mine gas controlling and utilization,it also received extensive attention of the industry. The ground drilling extraction gas involves many technical process,and the ground drilling extraction project deployment and gas extraction effect analysis is the key to the project implementation,therefore the research of the ground extraction gas project deployment technology and extraction effect analysis have important theoretical and practical value.Lishu Coal Mine is located in Jixi mining area in northeast, with large gas content, the No. 14 coal seam of the main mining belongs to the outburst coal seam. Since 2012, CCTEG Xi'an Research Institute is carried out two CBM surface development tests to No. 14 coal seam in the mine, and has achieved initial success, fully demonstrates the feasibility of coal bed gas pumping No. 14 coal seam floor, but the ground gas drainage is still in its infancy in Lishu Coal mine, project deployment and extraction effect still need further study. Therefore, this paper based on the engineering test, based on the analysis of factors of Lishu Coal Mine CBM geological conditions and coal reservoir characteristics and CBM resources and so on, the CBM well existing drainage was analyzed; With CBM-SIM of CBM well numerical simulation software to simulate the mining history, reservoir parameter optimization was realized; Also qualitative analysis and optimized ground drainage and well pattern in Lishu Coal mine, On the basis of setting the 7 kinds of well spacing, with the help of CBM-SIM software, the productivity of different well spacing and the change of gas content were predicted, and the optimum well spacing was determined in the coal mine preparation area and planning area; the final preparation area, the planning area were designed well deployment plan, CBM-SIM software was used to predict the gas drainage effect in the preparation area in 5 years, and the dynamic change of gas content, extraction rate and recovery rate of 5 years, 10 years and 15 years in the planning area.The results of the study show that:(1) well spacing selection, it is suitable for selection of 200 m × 250 m well spacing in the preparation area, the planning area should select the 300 m × 300 m well spacing;(2) Analysis of pumping effect, the preparation area for 5 years, the recovery rate is 32.30%~38.20%, the gas content from 11m3/t can be reduced to 3~8m3/t; Planning area drainage for 5 years, the recovery rate is 30.00%~39.05%, and the gas content is reduced from 11~15 to 3~12m3/t; drainage for 10 years, the recovery rate is 41.78%~52.06%, the gas content can be reduced from 11~15m3/t to 2~11m3/t; drainage for 15 years, the recovery rate is 48.20%~62.04%, the gas content can be reduced from 11~15m3/t to 2~11m3/t. The drilling scheme drainage effect is well, gas content decreases by a large margin, at the same time, it also shows that the ground gas drainage is an effective way to reduce the gas content.