穿越多采空区地面钻井抽采试验及井身破断特性分析

Drainage Test of Surface Drilling Crossing Multi-gobs and Characteristics Analysis of Well Breakdown

地面钻井是一种高效的瓦斯抽采技术。针对五虎山煤矿开采煤层上方存在多个老采空区的情况,成功应用了偏心钻头配合管靴的跟管钻进工艺,有效解决了钻井穿越采空区的卡钻、埋钻问题,顺利完成钻井施工。地面钻井共抽采瓦斯9 d,累计抽采纯瓦斯2.31×104m3,由于抽采效果不佳而被迫停抽。运用ABAQUS有限元软件研究了采动作用下套管的受力特性,结果表明上覆老采空区位置钻井套管的应力较大,是钻井破断的关键位置。

Coalbed methane can be extracted by surface drilling efficiently. According to the situation that there are multiple gobs above the mining seam in Wuhushan Coal Mine, pipe -follow drilling technology using eccentric bit combined with pipe shoe was ap- plied to solve the problems effectively of drill sticking or burying when borehole passed through gob. Based on the pipe - follow drilling technology, surface drilling operation was successfully completed. During the longwall face mining, the surface drilling extracted gas for 9 days, and the accumulated drainage amount of pure gas was 2.31 ~ 104 m3. Due to the poor drainage effect, drainage was forced to stop. The forced characteristics of casing under the action of mining disturbance were researched by using ABAQUS finite element softwaro. The results show that the stress of drilling casing in the position of overlying gob was greater, and this was the key position for the drilling breaking.