碎软低渗煤层煤层气直井间接压裂技术及应用实践

Technology and application of indirect fracturing in CBM vertical well of broken and soft coal seam with low permeability

为了解决碎软低渗煤层压裂改造过程中煤粉产出和压裂裂缝不易延伸的技术瓶颈,采用地应力和数值模拟分析方法,对煤层气井间接压裂适应性及裂缝展布规律进行分析研究,并在湖南洪山殿矿区进行了间接压裂工程实践。结果表明:间接压裂可有效提高碎软低渗煤层的压裂改造效果,增加压裂裂缝长度,当顶底板为脆性砂岩时,更加有利于间接压裂;洪山殿矿区HC01井取得了单井产气量1850m^3/d的良好产气效果,表明“大排量、大砂量、高前置液比、中砂比”的活性水间接压裂技术适用于碎软低渗煤层的增产改造;同时,可钻桥塞电缆射孔联作技术的应用可有效缩短煤层气井多煤层段压裂改造的施工周期,提高压裂施工时效性。

In order to solve the problems of pulverized coal output and fracturing fracture not easy to extend during fracturing operation in the broken and soft coal seam with low permeability,the adaptability and fracturing fracture distribution of CBM during indirect fracturing are studied by means of in-situ stress and numerical simulation,and the engineering practice of indirect fracturing has been tested in Hongshandian mining area of Hunan Province.The results show that indirect fracturing can effectively improve the fracturing effect of the broken and soft coal seam with low permeability,and increase the fracture length.When the roof and floor are lithologicaly brittle sandstone,it is more conducive to indirect fracturing.Well HC01 has achieved a good gas production efficiency of 1 850 m^3/d,indicating that the active water indirect fracturing technology of "large displacement,large sand volume,high prepad ratio and medium sand ratio" is suitable for fracturing of the broken and soft coal seam with low permeability.At the same time,the application of drilling bridge plug cable perforation technology can effectively shorten the construction period of multi-seam fracturing in CBM well and improve the efficiency of fracturing operation.