钠蒙脱石表面水化评价方法研究

页岩地层黏土矿物表面水化的抑制仍然存在技术瓶颈，亟需建立抑制黏土矿物表面水化的新理论和新方法。文章主要以泥页岩中常见的钠蒙脱石黏土矿物样品为研究对象， 通过等温吸附法研究其表面水化程度，采用Ｘ射线衍射分析法、热重分析法和核磁共振分析法研究了钠蒙脱石的结合水类型及含量，建立了钠蒙脱石结合水的定量评价方法。实验结果表明：随着相对湿度的增加， 钠蒙脱石的基底间距呈阶梯状逐步增加，当相对湿度为1.00 时，钠蒙脱石可达到四层水化；热重分析可定量区分钠蒙脱石的阳离子层间水、层间表面水和自由水。核磁共振分析能定量区分黏土矿物的结合水和自由水。此举可为建立抑制黏土矿物表面水化定量评价方法提供理论和实验支撑。

Study on Evaluation of Hydration Degree of Montmorillonite Surface

At the present stage, there are still technical bottlenecks in the suppression of surface hydration of clay minerals, and there is an urgent need to establish new theories and methods for the suppression of surface hydration of clay minerals. This paper mainly studies the surface hydration degree of montmorillonite clay mineral samples commonly found in mud shale by isothermal adsorption method, and studied the type and content of bound water of sodium montmorillonite by using X-ray diffraction analysis, thermogravimetric analysis and low-field NMR analysis, and established a quantitative evaluation method of bound water of sodium montmorillonite. The experimental results showed that the basal spacing of sodium montmorillonite increased in a step-like manner with the increase of relative humidity, and when the relative humidity was 1.00,sodium montmorillonite could reach four layers of hydration. Thermogravimetric analysis could quantitatively distinguish the cationic interlayer water, interlayer surface water and free water of sodium montmorillonite. Low-field NMR analysis can quantitatively distinguish the bound water and free water of clay minerals. This can provide theoretical and experimental support for the establishment of a quantitative evaluation method for inhibiting surface hydration of clay minerals.