煤层气综合抽采技术及应用研究

Study on comprehensive coalbed methane extraction technology and application

摘要:

通过在井下大巷实施井下水平井与原有地面U型井对接连通，实现将地面抽采改为井下正压抽采，可解决煤层气地面抽采的诸多不利，有利于降低抽采成本，改进抽采管理水平。目前煤矿瓦斯治理采用的井下抽放方式为常压钻孔负压抽放，在钻孔过程中煤层原始地层压力因快速降压，导致出现损害瓦斯通道的压实效应；正压直接转换为无节制措施的负压抽放，初速过大易造成速敏效应，从而使瓦斯抽采影响范围小及瓦斯浓度和采收率低，而且产量衰减快，增加煤矿井下钻井工程量，经济性很差。为解决这个问题，通过对保德煤矿煤层气综合抽采技术及应用研究，采用井下正压抽采，可以有效提高瓦斯最终采收率，为降低保德煤矿抽采成本开辟了新的途径，项目具有广泛推广价值。

Abstract:

With an underground horizontal well in the underground roadway connected to the original surface extraction “U” type well, CBM surface extraction can be converted to the underground positive pressure extraction, which can eliminate many disadvantages of surface extraction of coalbed methane, help to reduce extraction cost, and improve extraction management. At present, for coal mine gas treatment, negative pressure drainage with atmospheric pressure boreholes is adopted, where in the process of drilling, the original formation pressure in the coal seam is reduced rapidly, leading to gas channel damage due to compaction effect. In order to solve this problem, the comprehensive coalbed methane extraction technology and application were investigated in Baode Coal Mine, where underground drainage at positive pressure was used. This method can effectively improve the final gas recovery; thus, providing a new way to reduce the extraction cost of Baode Coal Mine. The method is worthy of extensive popularization.