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以黔西北地区某区块煤层气井为研究对象,分析造成压裂施工压力异常主要有煤体结构差、射孔程度不完善和煤储层自身特性三个方面的原因。一是煤体结构差会造成井眼严重扩径,固井水泥环厚,近井地带煤层严重污染;二是射孔程度不完善造成有效孔眼少,射孔孔眼摩阻大且未能有效沟通煤层;三是煤层所处的地应力环境使人工裂缝趋于复杂,且煤层杨氏模量低、泊松比高的特点易使产生人工裂缝宽而短,压裂液滤失严重,造成砂堵。针对以上三点,分别从钻井、射孔和压裂三个方面提出相应的技术措施,为后期煤层气井的压裂提供指导。
Taking a block of coalbed methane wells in the northwest of Guizhou Province as the research object, the causes of abnormal pressure in the fracturing are analyzed mainly due to the poor coal structure, perforation imperfections and coal reservoir properties. First, the poor coal structure will cause a serious expansion of the borehole, cementing cement ring thick, near the well seam coal seam serious pollution; Second imperfect perforation caused less effective perforation, perforation pore friction is large and failed to effectively communicate Coal seam; Third, the stress environment in which the coal seam is located makes the artificial cracks become more complex, and the characteristics of low Young’s modulus and high Poisson’s ratio in the coal seam are easy to make the artificial fractures are wide and short, Blocking. According to the above three points, the corresponding technical measures are put forward respectively from drilling, perforation and fracturing so as to provide guidance for the later fracturing of coalbed methane wells.