水基钻井液用胺类页岩抑制剂特性及作用机理

Properties and Mechanism of Shale Inhibitor for Water-based Drilling Fluid

针对油气井钻井过程中泥页岩地层井壁失稳的难题,基于钻进液技术要求,结合分子结构优化设计,以三乙醇胺、顺丁烯二酸酐和冰乙酸为原料,研制了环保聚胺强抑制剂HGI体系。采用传统评价方法(粒度分布实验、流变性实验)与新型评价方法(X射线衍射分析、热重分析)相结合的方式评价了HGI的抑制性能,并对抑制作用机理进行了探讨。研究结果表明:HGI体系的抑制性优于其同类聚胺抑制剂UHIB-Ⅰ、UHIB-Ⅱ的,能有效抑制泥页岩水化和分散,表现出更加突出的抑制性能。HGI以插层方式进入黏土晶层空间,通过与黏土表面的静电作用、氢键作用吸附在黏土晶层表面。HGI分子中的羟基以其独特的"遥爪"状结构与黏土晶层表面的金属离子形成螯合键,紧密地包裹在黏土晶层表面,也起到一定的吸附作用。利用X射线衍射分析测试黏土晶层间距的方法弥补了传统方式常温常压线性膨胀法对小分子胺类抑制剂性能评价的不足。

Aimed at the problem of sluice instability in silt formation in oil and gas well drilling, based on the technical requirements of drilling fluid and the optimization of molecular structure, a type of environmental protection polyamine strong inhibitor HGI was developed using triethanolamine, maleic anhydride and glacial acetic acid as raw materials. The inhibition performance of HGI was discussed by using the new evaluation method （X-ray diffraction analysis, thermogravimetric analysis） and the traditional evaluation method （particle size distribution experiment, rheological experiment）, in addition, the inhibition mechanism of HGI was analyzed. The results showed that the HGI could effectively inhibit the hydration and dispersion of shale, showing more prominent inhibitory performance than that of the similar polyamine inhibitor UHIB- I and UHIB- II. The HGI molecules was intercalated into the interlayer space of the clay by electrostatic interaction and hydrogen-bond interaction between HGI molecules and the surface of clay crystal layer. In addition, the hydroxyl groups in the HGI molecules formed a chelating bond with the metal ions on the surface of the clay crystal layer with their unique ＂claw＂ structure, which was tightly wrapped on the surface of the clay crystal layer and played a certain role. The new characterization system of measurement of crystal interlayer spacing by X-ray diffraction analysis, could make up the deficiency of the traditional method of linear expansion of normal temperature and normal pressure.