川东北铁北1侧HF井二叠系超深层页岩气压裂技术

Fracturing Technology for Permian Ultra-Deep Shale Gas in Well Tiebei 1 Sidetrack-HF in Northeastern Sichuan

  • 摘要: 川东北铁北1侧HF井为垂深超过5 300 m的二叠系超深层页岩气水平井,天然裂缝欠发育,水平两向主应力差达13.5~17.7 MPa,纵向发育多条灰岩薄夹层,压裂改造面临施工压力高、缝宽窄、加砂困难及裂缝纵向扩展受限等多重挑战。基于岩心实验评价了大隆组页岩力学特征与脆性特征,结合地质工程一体化模型,分析了前置液排量、黏度及注入体积对裂缝纵向扩展的协同调控规律,量化了穿行不同小层时的压裂参数,明确了不同尺度裂缝的加砂方式,形成了以“细密布缝+非均匀后效射孔+高黏高排造缝+多级粒径支撑剂分级支撑”为核心的压裂技术体系。铁北1侧HF井应用后获得高产气流,实现了二叠系超深层页岩气勘探突破。研究结果为川东北地区超深层页岩气资源的高效开发动用提供了技术保障。

     

    Abstract: Well Tiebei 1 Sidetrack-HF is a Permian ultra-deep shale gas horizontal well with a vertical depth exceeding 5 300 m. It is characterized by poorly developed natural fractures, a differential horizontal in-situ principal stress of 13.5–17.7 MPa, and multiple thin limestone interbeds developed vertically. Fracturing stimulation faces multiple challenges, including high treatment pressure, narrow fracture widths, difficulty in proppant placement, and limited vertical fracture propagation, etc. Based on core experiments, the mechanical and brittle characteristics of the Dalong Formation shale were evaluated. Combined with a geology-engineering integration model, the synergistic regulation laws of pad fluid flow rate, viscosity, and injection volume on vertical fracture propagation were analyzed, fracturing parameters for penetrating different sublayers were quantified, and proppant placement strategies for fractures with different scales were clarified. A fracturing technology system with the core principles of “fine and dense fracture layout + non-uniform aftereffect perforation + high-viscosity and high-flow-rate fracturing + multi-size proppant staged placement” was established. After application in Well Tiebei 1 Sidetrack-HF, high-yield gas flow was achieved, marking a breakthrough in Permian ultra-deep shale gas exploration. The research results provide technical support for the efficient development and mobilization of ultra-deep shale gas resources in northeastern Sichuan.

     

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