合成锂皂石在超高温水基钻井液中的增粘机理研究

As the exploration and development of oil/gas resources in deep strata and hot dry rock geothermal resource, the formation temperature in bottom hole will be up to 200℃, and the drilling fluids in the borehole will long term be in high temperature environment. At high temperature, the performance of water-based drilling fluids makes drastic changes as a result of the degradation of polymer additives, for instance, the viscosity decreases obviously, cuttings carrying capacity is insufficient. Owing to the fact that the existing high temperature resistant viscosifier cannot meet the performance requirement of high temperature above 200℃ water-based drilling fluids, we proposes using laponite as anti-ultra-high temperature viscosifying additive. The experimental methods such as HTHP rheometer, laser particle size analyzer and Zeta potential analyzer etc will be adopted to determine the performance of aqueous laponite dispersions and bentonite dispersion with laponite in terms of rheology, particle size distribution and particle Zeta potential at 200℃~240℃, and the dispersion mechanism of laponite and interaction mechanism between laponite and bentonite particle at ultra-high temperature will be researched. Through this project research, the reason of ultra-high temperature resistant thickening property of laponite and how the interaction between laponite and bentonite particles works at ultra-high temperature might be theoretically revealed and the viscosifying mechanism of laponite in ultra-high temperature water-based drilling fluids will be analysed. The research results of this project could provide a theoretical basis for high temperature above 200℃ water-based drilling fluids, and promote the development of China’s ultra-high temperature drilling fluids technology.

随着我国深部油气资源与干热岩资源勘查开发，井底地层温度将超过200℃，井内钻井液将长期处于高温环境。在高温下，水基钻井液中的聚合物类处理剂会降解、使钻井液性能发生剧变，例如钻井液粘度明显降低、岩屑携带能力不足。针对现有抗高温增粘剂不能满足耐200℃以上高温水基钻井液要求，提出采用合成锂皂石作为超高温水基钻井液用增粘剂。采用高温高压流变仪、激光粒度仪及Zeta电位仪等实验仪器测定合成锂皂石分散体系以及合成锂皂石作为增粘剂与膨润土基浆在200~240℃下流变学、颗粒粒度分布及颗粒Zeta电位等性能，研究超高温下合成锂皂石分散机理以及合成锂皂石与膨润土颗粒的作用机理。通过本项目研究，可望在理论上揭示合成锂皂石具有抗高温增稠性能的原因，并剖析合成锂皂石在超高温水基钻井液中的增粘机理。本项目研究成果将为抗温200℃以上高温水基钻井液技术发展提供理论基础，并推动我国超高温水基钻井液技术发展。

随着我国深部油气资源及干热岩资源勘查开发，井底地层温度将超过240℃，井内钻井液将长期处于高温环境。在高温下，水基钻井液中的膨润土颗粒会发生高温分散或高温聚结，聚合物类增粘剂会降解、使钻井液性能发生剧变。超高温条件下水基钻井液流变性能稳定已成为高温井钻探面临的“卡脖子”技术难题。合成锂皂石是一种人工合成的2:1型层状硅酸盐矿物，具有良好的分散性、增稠性及触变性能。本项目开展了合成锂皂石在超高温水基钻井液中的增粘机理研究，主要研究内容及成果如下：（1）采用X射线粉晶衍射、扫描电镜及红外光谱等对合成锂皂石及其他造浆材料进行了结构表征与理化性能测试，不同造浆材料颗粒形貌差异较大，合成锂皂石层间离子为Na+与Li+，其阳离子交换容量（CEC）为149.1mmol/100g，远高于优质钠膨润土的CEC值；（2）采用六速旋转粘度计、激光粒度仪及Zeta电位仪等分析了合成锂皂石加量、pH值及温度对合成锂皂石分散体系的流变学、颗粒粒径及Zeta电位等性能影响，阐释了合成锂皂石在水相中的高温增稠机理。高温下合成锂皂石分散体系的表观黏度基本保持不变，2%合成锂皂石分散体系在180~240℃高温老化16h后，其表观黏度在22~24mPa·s变化；（3）研究了合成锂皂石加量、pH值及温度对含合成锂皂石增粘剂在超高温水基钻井液中的流变学、降滤失性、颗粒粒径及zeta电位等性能影响，揭示了合成锂皂石在超高温水基钻井液中的增粘机理。在4%钠膨润土基浆中加入1%合成锂皂石，240℃高温老化16 h前后钻井液的表观黏度均为16.5mPa﹒s；4）对比分析了合成锂皂石与现有高温增粘剂在水基钻井液中的增粘性能，并开展了合成锂皂石与其他钻井液高温处理剂配伍性研究。研究结果表明合成锂皂石具有优良的増粘性能和热稳定性，抗温能力可达240 ℃，适合用作超高温增粘剂，在超高温水基钻井液中具有广阔的应用前景。研究成果对促进国内超高温水基钻井液技术的应用和发展具有重要的理论价值和现实意义。