摘要
针对超深层(>4000 m)多岩性界面煤岩储层水力压裂裂缝纵向穿层难题,本文构建了一套新型真三轴物理模拟实验方法,系统研究了四川盆地龙潭组深层煤岩在不同地质-工程参数耦合作用下的裂缝扩展规律。通过构建不同厚度组合的页岩-煤岩-页岩试样,结合声发射监测与三维裂缝重构技术,揭示了煤岩、页岩在不同厚度组合下最小水平主应力差、压裂液黏度及排量对裂缝穿层行为的控制机制。实验结果表明,层间最小水平主应力差减小时裂缝更易穿层;压裂液黏度升高有助于裂缝突破界面;在高层间最小水平主应力差与低黏度条件下,排量与裂缝穿层能力呈非线性关系,排量增加初期裂缝开始突破界面,继续增大排量后贯通效果未进一步提升;储层、隔层厚度过大均会阻碍水力裂缝的垂向扩展,合适的岩层厚度分布下更有助于裂缝穿层。本研究首次量化了超深层煤岩水力压裂的“黏度-应力差-排量-厚度”多参数耦合机制,为四川盆地龙潭组超深层煤层气高效开发提供了理论支撑。
To address the challenge of vertical fracture propagation across multi-lithologic coal-shale interfaces in ultra-deep(>4,000 m)reservoirs,this study developed a novel true triaxial physical simulation method to systematically investigate the fracture propagation behavior of deep coal formations in the Longtan Formation,Sichuan Basin,under various coupled geological and engineering parameters.Using shale-coal-shale layered specimens with different thickness combinations,combined with acoustic emission monitoring and 3D fracture reconstruction,the controlling effects of interlayer minimum horizontal stress difference,fluid viscosity,and injection rate on fracture crossing behavior were systematically examined.Results indicate that a reduction in interlayer stress difference facilitates vertical fracture propagation across interfaces;higher fluid viscosity improves interface breakthrough capacity;under high interlayer stress difference and low-viscosity conditions,fracture crossing exhibits a nonlinear response to injection rate,where continued rate increase does not enhance connectivity.Additionally,excessive reservoir or interlayer thickness suppresses vertical fracture growth,while coordinated thickness distribution promotes effective interlayer connectivity.This study quantitatively reveals the coupled mechanism of viscosity-stress difference-injection rate-thickness in ultra-deep hydraulic fracturing,providing theoretical support for efficient CBM development in the Longtan Formation of the Sichuan Basin.
作者
杨兆中
廖宇
李小刚
易良平
易多
刘建平
YANG Zhaozhong;LIAO Yu;LI Xiaogang;YI Liangping;YI Duo;LIU Jianping(National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China;School of Mechanical Engineering,Southwest Petroleum University,Chengdu,Sichuan 610500,China)
出处
《钻采工艺》
北大核心
2025年第3期147-154,共8页
Drilling & Production Technology
基金
中国工程院战略研究与咨询项目“我国煤层气有效开发战略研究”(编号:2021-XY-24)。
关键词
多岩性界面
真三轴
纵向扩展
裂缝形态
地质-工程参数耦合
multiple lithologic interfaces
true triaxial
vertical fracture propagation
fracture morphology
cou⁃pling of geological-engineering parameters
