基于表面活性“开关”的泡沫钻井液循环利用机理研究

For the conventional foam is difficult to recycle, thus result in high cost of foam drilling fluid, this research proposed amidine long-chain alkyl compound which has CO2/N2 -"Switch" surface-active as the foaming agent of foam drilling. Through controlling the surface-active switch to realize quickly foaming and defoaming recycling, firstly, this project intends to establish the relationship mapping between structure of amidine long-chain alkyl compound and surface-activity, synthesize the target amidine long-chain alkyl compound by adopted amide acetal method and analyze the rules of environmental parameters influence on the surface-activity by the use of dynamic interfacial tension meter and electro-conductivity meter. On the other hand, through adopted Waring Blender mixing method, the near-infrared scanner and the interfacial film intensity meter and others, this project is going to analyze the variation of foaming stability of amidine long-chain alkyl compound with environmental conditions and through the use of high temperature and pressure rheometer, high temperature and pressure density devices, it reveals the variation and rheological properties of amidine long-chain alkyl compound foam in the wellbore conditions as well as adpoted the dynamic interfacial tension meter, dynamic light scattering and microscopic methods combined with flow simulation platform of wellbore and macro-experimental methods , this research in-depth analyzes the excitation conditions and amidine long-chain alkyl compound surface-active switch conversion mechanism and explores the controlling principles and methods of foam cyclic utilization. At last, this project intents to provide the theoretical foundation and technical support for the new method of foam drilling fluid cyclic utilization.

针对常规泡沫难以循环利用，导致泡沫钻井液成本高昂的问题，提出以具有CO2/空气（N2）"开关"表面活性的脒基长链烷烃化合物作为泡沫钻井起泡剂，通过控制其表面活性的开和关来实现泡沫快速起泡消泡循环利用的思路。本项目拟建立脒基化合物结构与表面活性的对应关系，采用酰胺缩醛法合成出目标脒基长链烷烃化合物；并用动态界面张力仪、电导率仪测试分析环境参数对表面活性的影响规律；采用近红外扫描仪、界面膜强度仪分析研究脒基长链烷烃化合物泡沫稳定性随环境条件的变化规律；利用高温高压流变仪、高温高压密度装置揭示井筒条件下脒基长链烷烃化合物泡沫的密度变化规律和流变特性；采用动态界面张力仪、动态光散射仪等微观方法结合井筒流动模拟试验平台宏观实验手段深入分析研究循环过程中脒基长链烷烃化合物表面活性开关的激发条件及转换机理，探索新的泡沫循环利用控制原理；为泡沫钻井流体循环利用新方法的建立提供理论基础和技术支持。

泡沫钻井液因密度低、滤失量小、携岩能力强而具有明显的防漏堵漏、提高钻速、保护油气层等优异特性，特别适用于低压、易漏及水敏性地层，但因泡沫的难以循环利用而导致钻井成本高、环境污染严重，使之难以推广应用，本项目基于此提出了一种开关型可循环泡沫钻井液。（1）以酰胺缩醛法合成了系列N’-长链烷基-N,N-二甲基乙脒及对应的碳酸氢盐，根据开关特性建立了CO2/N2开关评判方法，运用电导率法测试了开关的灵敏性，考察了温度、酸、碱、盐等环境条件对开关的影响规律。（2）建立了充气起泡实验装置，确定了CO2/N2开关激发条件，对产物进行了自循环实验测试和CO2/N2开关条件下泡沫性能的影响因素分析。（3）构建了具有自动起泡消泡功能的开关型泡可循环泡沫钻井液体系，评价了其抗温、抗盐及抗油污染性能，实验研究了开关型泡沫钻井液体系的流变特性及高温高压密度特性。（4）并在开关型泡沫钻井流体起/消泡循环利用实验研究基础上，提出了实现泡沫钻井液可循环起泡/消泡快速转换的新方法及调控技术。对促进低密度可循环泡沫钻井技术的应用和发展具有重要的理论引导和实际意义。