淮北芦岭煤矿煤层顶板水平井煤层气抽采效果分析

淮北芦岭煤矿为高瓦斯突出矿井，煤层碎软低渗，瓦斯抽采困难。应用“十二五”期间开发的紧邻煤层顶板水平井分段压裂煤层气高效抽采技术，试验井已取得产气突破。为了深入分析评价地面煤层气抽采对煤矿瓦斯灾害的防治效果，基于目标煤层特征，分析煤层顶板水平井的产气规律，利用产能数值模拟技术，对生产井数据进行了历史拟合，在此基础上，进行水平井产能预测，分析水平井抽采过程中煤层气含量和储层压力变化趋势。结果表明:水平井抽采影响范围主要为裂缝和近井筒区域，井筒-裂缝系统外部区域受影响较小；水平井影响范围随抽采时间的延长逐渐增大，预测1、3、5、8、10 a的影响面积分别为0.113、0.193、0.242、0.311、0.350 km2；随着水平井抽采时间的延长，剩余含气量和储层压力逐渐降低，预测水平井抽采5 a，水平井控制范围内瓦斯含量最低可降至2.86 m3/t，平均可降至4.2 m3/t，降低50.6%。储层压力最低可降至0.85 MPa，平均可降至2.30 MPa，降低66.2%。煤层顶板水平井技术对煤层气开发和瓦斯灾害防治效果显著，是实现碎软低渗煤层瓦斯地面预抽的有效手段。 

Analysis on the CBM extraction effect of the horizontal wells in the coal seam roof in Luling coal mine in Huaibei

Huaibei Luling Coal Mine is a mine with high risk of gas outburst. The coal seams are broken and soft have low permeability, the gas extraction is difficult. The high-efficiency gas extraction technology of staged hydraulic fracturing horizontal well next to seam roof, developed during the 12th Five Year Plan, was applied. The pilot test achieved a breakthrough in gas production. However, there are few researches on the effect of horizontal well drainage on the prevention and control of gas disasters. In this paper, the reservoir characteristics of the target coal seams and the gas production law of the pilot horizontal well were analyzed. Then, the numerical simulation technology was employed to historically match the production data. On this basis, the horizontal well production was predicted for ten years. The change law of coalbed methane gas content and reservoir pressure over time in the process of horizontal well extraction was analyzed. And the effect of coalbed methane extraction on coal mine gas control was evaluated. The results show that:The influence area of horizontal well drainage is mainly near the hydraulic fracture and wellbore, and the area outside the wellbore-fracture system is less affected; The influence area of horizontal well gradually increases with the production time. It is predicted that the area of influence scope of 1 a, 3 a, 5 a, 8 a, and 10 a is 0.113, 0.193, 0.242, 0.311, 0.350 km2, respectively; With the drainage time, the gas content and reservoir pressure gradually decrease. It is predicted that after 5 years of production, the gas content within the control range of the horizontal well can be reduced to 2.86 m3/t at the lowest, and the average can be reduced to 4.2 m3/t, with a reduction ratio of 50.6%. The reservoir pressure can be reduced to 0.85 MPa at the lowest, and 2.30 MPa on average, with a reduction ratio of 66.2%; Coal seam roof horizontal well technology has significant effects on coalbed methane development and gas disaster prevention and control, and is an effective method to achieve ground pre-drainage of gas from broken, soft and low-permeability coal seams.