寺河井田L型井产气效果影响因素的初步研究

Engineering Factors of Gas Production in L-type Wells in Sihe Mine

山西晋煤集团部分高瓦斯矿井虽经采取本煤层抽放、顶板走向钻孔抽放等方法,在回采过程中回风瓦斯浓度仍然经常达到临界值,影响了工作面的安全生产。本文对已投运的3口L型井从井身结构差异、压裂前后运行曲线、压裂施工效果三方面进行分析,探寻影响L型井产气效果的工程因素,得出主要结论有:裸眼段平均坡度对L型井产气效果存在显著影响;水力压裂施工对L型井产气至关重要,而产气效果与压裂时工作面已采过裸眼段的长度和相对比例无直接关联。今后压裂时,建议提高最大排量并相应增大入地液量,以应对部分L型井可能存在的畅通程度较差的情况。

Three L-type wells of Jincheng Coal Group are compared to explore the influential factors of gas production, in terms of structure difference, operational curves before and after fracturing, and fracturing effect. The results show that.the average slope of open hole signifi- cantly affects the gas production; hydraulic fracturing is critical for the gas production of the L- type wells; the gas production has no direct relationship with the length of the open slope and its relative scale. In addition, the digging length of working face determines the absolute quantity of gas emission. If the wells are unblocked, the digging length is positively correlated with the gas drainage quantity and concentration. On the other hand, the variation of drainage parameters lag behind and the lagging time is correlated with the total amount of free methane in fissure of goal and drainage speed. When working face passes the open hole, the drainage amount, concentra- tion, and negative pressure go worse gradually and the negative pressure shows the opposite trend with the drainage flow.