School of Resources, China University of Geosciences (Wuhan) National Energy Key Lab of Coal and Coalbed
Methane Co Mining Technology, Shanxi Jincheng Anthracite Mining Group Corporation Limited

为了研究煤体结构对煤层气开发的影响,对比了沁南地区3号煤层中原生结构煤、碎裂煤、碎粒煤、糜棱煤等不同煤体结构的钻井、压裂、排采资料,并对部分煤矿进行了井下观测分析。研究发现煤体结构越破碎,井壁稳定性越差,井径、抽采孔钻屑量越大,同时,储层污染范围与井径大致呈正相关关系;碎粒煤及糜棱煤发育处,井筒周围形成厚层的水泥环,水力压裂初始施工压力将快速上升,导致水泥环破裂,同时压裂液的大量滤失会降低压裂裂缝的延伸范围,甚至导致砂堵等工程问题;在排采过程中,煤层水及煤层气均有携带煤粉的能力,易造成排采通道的堵塞,导致气井产能迅速降低,同时也容易造成裂缝闭合,降低解吸范围,煤体结构越破碎,煤粉产出越多,裂缝闭合越严重。

In order to study the coal structure affected to coalbed methane development, an information comparison was conducted on the dilling, fracturing and dr ainage mining to different coal structure of primary coal, fragmented coal, fine coal and mylonite coal from No.3seam in Qinnan Region, and underground observation a nd analysis were conducted in some mines.The study showed the coal structure was more broken, the stability of well wall would be poorer and the diameter of well and drilling cuttings from the gas drainage mining borehole would be higher.Meanwhile, the reservoir polluted scope and the well diameters would be in a positive relationsh ip.At fine coal and mylonite coal developed area, thick cement rings formed around well wall and at the initial hydraulic fracturing operation, the pressure would be rapid ly increased and the cement ring could be broken.Meanwhile, great amount fracturing liquid lost would reduce the expansion scope of the fractured cracks and even ca use sand jammed and other engineering problems.During the gas drainage mining process, the coalbed water and coalbed methane would both have the ability to carry coal powder and thus the gas drainage mining channel would be jammed, the gas well production would be rapidly reduced, the crack closure could be easily caused a nd gas desorption scope would be reduced.The more broken the coal structure was, the higher production of the coal powder would be and the more serious crack clos ure would be.

国家科技重大专项资助项目(2011ZX05034-002)；山西省煤层气联合研究基金资助项目(2012012007)；