贵州复杂地层应力扰动压裂技术研究及应用

    Research and application of stress disturbance fracturing technology in complex formations in Guizhou Province

    • 摘要: 贵州含煤地层煤层多、煤层薄、夹矸多,岩性变化快,其复杂地层特点增加了煤层气井压裂施工难度。以金佳煤矿煤层气井为例,研究复杂地层压裂改造风险及压裂工艺技术,探索应力扰动下二次停泵压裂工艺技术适应性。工程实践表明:金佳煤矿煤系地层岩性变化复杂,地层岩性可划分为5种组合模式;多煤层及多分层煤层采取“避射、扩射、选射、连射、定向射孔”等方式,可降低压裂施工难度;多煤层合层压裂及多分层煤层压裂改造,采取二次停泵压裂工艺,促进地层应力重新分布及压裂裂缝转向,提高了储层压裂改造效果;研究区2口煤层气井实施二次停泵压裂工艺,其压裂施工曲线、停泵后压力变化及产气效果均显示该压裂工艺对储层改造效果较好。

       

      Abstract: Guizhou has many coal seams, thin coal seams, many gangues, and rapid lithology changes. Its complex strata characteristics increase the difficulty of fracturing CBM wells. Taking coalbed methane well in Jinjia Coal Mine as an example, we research the risk of complex formation fracturing and fracturing technology, and explore the adaptability of secondary pump-stop fracturing technology under stress disturbance. Engineering practice show that the lithology of coal measures in Jinjia Coal Mine has complex changes, and the lithology can be divided into 5 combination modes; multi-coal and multi-layered coal seams adopt methods such as “avoidance, expansion, selective injection, continuous injection, and directional perforation”, which can reduce the difficulty of fracturing construction. Multi-seam combined layer fracturing and multi-layer coal seam fracturing reform adopted the secondary stop pump fracturing technology, promoted the formation stress redistribution and fracture diversion, and improved the effect of reservoir fracturing reform; two coalbed methane wells in the study area implemented a secondary pumping-off fracturing process. The fracturing construction curve, pressure changes after pumping-off, and gas production effect all show that the fracturing process has a better effect on reservoir reconstruction.

       

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