页岩气钻探胶凝时控水泥基护壁堵漏材料研究

Study on cement-based materials with controllable gelation time for wellbore protection and leakage sealing in shale gas drilling

摘要:

针对我国页岩气等深部钻探面临的严重漏失与孔壁失稳难题，本文提出了一种胶凝时控的护壁堵漏思路，并在硅酸盐水泥的基础上复配有机酸、氟化钠、三乙醇胺及硫酸铝，成功研制一种胶凝时控水泥基护壁堵漏材料，实现对浆液凝结时间的精准调控，同时采用析因试验优化配方并建立可泵期（PPD）及可泵期与初凝时间间隔（IST）预测模型，结合热重分析与扫描电镜揭示其水化机理。结果表明：该材料表现出良好的胶凝时控特性，并具备较快的凝结响应能力，PPD可在10~60 min内精准调控，IST最小为12 min；7 d抗压强度达18.8~27.5 MPa，可满足工程强度需求。热重与微观分析表明：四种外加剂早期均抑制水泥熟料水化反应，后期均转化为促进作用，且存在明确的抑制-促进转换节点；四者通过动态协同作用形成“早期抑制-后期促进”双效调控机制，赋予浆液胶凝时控特性；其中有机酸仅短期抑制水化，7 d后C-S-H大量生成，结构致密化保障长期强度。本研究解决了传统水泥浆堵漏中浆液流失与凝结时效难以兼顾的难题，为深部页岩气钻探护壁堵漏提供了新的技术支撑。

Abstract:

To address the severe mud loss and borehole wall instability encountered in deep drilling operations such as shale gas exploration in China， this study proposes a gelation time-controlled strategy for wellbore stabilization and leakage sealing. A corresponding gelation time-controlled cement-based wellbore protection and leakage sealing material was successfully developed by compounding Portland cement with organic acid， sodium fluoride， triethanolamine， and aluminum sulfate， enabling precise regulation of the slurry''s setting behavior. The formulation was optimized through factorial design， and predictive models were established for the pumpable period （PPD） and the interval between pumpable period and initial setting time （IST）. The hydration mechanism was elucidated using thermogravimetric （TG-DTG） analysis and scanning electron microscopy （SEM）. Results demonstrate that the material exhibits excellent gelation time-control characteristics and rapid setting response： the PPD can be precisely adjusted within 10~60 min， with a minimum IST of 12 min； the 7-day compressive strength ranges from 18.8 to 27.5 MPa， meeting engineering strength requirements. TG-DTG and microstructural analyses indicate that all four admixtures initially inhibit cement clinker hydration， later transitioning into a promoting effect， with a distinct inhibition-to-acceleration transition point. Their dynamic synergistic interaction establishes a dual-effect control mechanism characterized by "early inhibition and late promotion"， which confers the gelation time-control property. Notably， organic acid only temporarily retards hydration， leading to substantial formation of C-S-H gel and microstructural densification after 7 days， thereby ensuring long-term strength development. This research resolves the longstanding engineering challenge of balancing slurry loss control and setting efficiency in conventional cement-based sealing operations， providing a novel technical solution for wellbore stabilization and leakage sealing in deep shale gas drilling.