突出煤层群井上下联合抽采防突模式与关键技术

Joint ground and underground gas extraction mode and its key technology for outburst coal seam group

我国煤层具有地应力大、渗透率低、瓦斯压力大、瓦斯含量高等特点,煤与瓦斯突出灾害严重。因此,需采取有效瓦斯治理措施,而单一井上瓦斯抽采技术容易出现抽采盲区,导致抽采效果不佳;单一井下瓦斯抽采技术工程量大、周期长,难以在短时间实现煤层消突。通过将井上与井下瓦斯抽采技术相互联合,实现井上下联合防突,是保障煤炭安全开采的关键技术之一。而在煤层群矿井中,需针对煤层间距离的远近采用不同的井上下联合防突模式,实现煤层群快速消突。对此,基于井上与井下联合抽采瓦斯技术优势,阐明了井上下联合防突“时空转换-优势互利”的内涵。井上地面井长时间、广覆盖抽采瓦斯实现煤层降突,换取井下作业空间,实现“时间换空间”;井下钻孔在井下作业空间内,精准抽采目标区域瓦斯实现目标区域快速消突,缩短目标区域消突时间,实现“空间换时间”,提升煤层瓦斯治理效果。针对近距离煤层群层间采动影响大等特点,提出了近距离煤层群“孔群覆盖-协同抽采”井上下联合防突典型模式,实现了瓦斯突出治理的超前规划、提前施工、整体消突。针对远距离煤层群采动卸压范围小等特点,提出了远距离煤层群“强化增透-递进抽采”井上下联合防突典型模式,实现了瓦斯突出治理的强化卸压、递进消突。自主研发了近远距离煤层群井上下联合防突关键技术,并以沙曲一矿与朱集西矿作为近远距离煤层群矿井典型案例进行应用效果分析。应用效果表明:在近距离煤层群沙曲一矿中释放抽采达标煤量约80万t,高效抽采瓦斯量约420万m^(3)。远距离煤层群朱集西矿中井下钻孔工程量减少约60%,抽采达标时间缩短约40%。

China’s coal seams are characterized by high ground stress,low permeability,high gas pressure,and high gas content,and their gas outburst hazards are serious.Therefore,some effective gas extraction measures must be taken for coal seams.However,only ground gas extraction technology is prone to emerge extraction gaps,resulting in poor extraction effects.Moreover,it is a challenge to achieve coal seam abatement in a short period because of the large work and extended period using underground gas extraction technology only.Combining ground and underground gas extraction technologies to achieve a joint ground and underground gas outburst prevention is one of the key technologies to ensure a safe coal mining.In the coal seam group mines,different modes of joint ground and underground gas outburst prevention should be adopted according to the distance between coal seams in order to rapidly eliminate gas outburst risk in the coal seam group.Based on the advantages of combined ground and underground gas extraction technology,the connotation of time and space conversion and complementary advantages of combined ground and underground gas outburst prevention technology is clarified.Long-time and comprehensive coverage extraction of gas from ground wells achieves a coal seam gas reduction in exchange for underground operation space.Underground drilling in the underground space accurately extracts gas from the target area,shortens the gas outburst prevention time and enhances the effect of coal seam gas extraction.Because of the characteristics of close distance coal seam groups,such as significant influence of interlayer mining,this paper puts forward a typical prevention model of gas outburst in close distance coal seam group“boreholes group coverage-cooperative extraction”,which realizes advance planning,advance construction and overall prevention of gas outburst.Given the characteristics of long distance coal seams with small mining pressure relief area,the typical model of“enhanced reflection improvement and progressive extraction”for the gas outburst prevention mode of joint ground and underground technology is proposed,which realizes the strengthening pressure relief,mining follow-up and progressive key gas outburst prevention in the management of long distance coal seams.In addition,the authors have independently developed the gas outburst prevention technology of joint ground and underground technology for close distance coal seams and long distance coal seams to further improve the gas outburst prevention effectiveness of joint ground and underground technology and analyzed the application effect by using the Shaqu No.1 Mine and Zhuji West Mine as typical cases.The application results show that the amount of coal mined in the Shaqu No.1 Mine in the close distance coal seam group is about 800 thousand tonnes,and the amount of gas efficiently extracted is about 4.2 million m^(3).In the long distance coal seam group of the Zhujixi Mine,the underground drilling quantity is reduced by about 60%,and the gas extraction standard time is shortened by about 40%.