黏土矿物组构对水化作用影响评价

泥页岩水化过程中黏土矿物起着主要的作用,但目前还缺少相关的定量描述研究。为此,利用SEM、X-粉晶衍射技术,对采自不同地区的泥岩和板岩在干燥状态、不同浸泡时间后的微观结构和含量进行分析及研究,分析黏土矿物的组构随浸泡时间的变化过程,并定量地分析其对水化过程的影响规律,研究泥页岩的软化过程。研究认为,(1)泥页岩、板岩中影响水化过程的内在因素是蒙脱石、高岭石、绿泥石和伊利石等黏土矿物的含量;(2)黏土矿物定向排列时水化作用效果较无序排列时的明显;(3)泥页岩的水化作用是一个渐进的过程,即在水化过程中流体介质首先使表面的黏土矿物软化,产生掉块;随着时间延长,流体沿裂缝、层理面向岩石内部渗透,黏土土矿物发生膨胀;无围岩限制作用时坍塌掉块持续发生;(4)泥浆中加入一定的无机盐有助于抑制水化过程的发生;压力增加将抑制水化过程的产生;温度升高则能促进泥页岩的水化过程。

Evaluation of impact of clay mineral fabrics on hydration process

Clay minerals play important roles in hydration process, while the role was lack of quantitative evaluation at present. Therefore, SEM and X-ray powder diffractometry technology were used to analyze the microstructure, components and contents of clay minerals, and the change of microstructures in dry condition and different wetting times. At the same time, expansion experiments in different conditions were performed to study the variation of mass and the structure during the hydration process. These experiments show that: (1) The inner factors affected the hydration process are the contents of clay minerals such as montmorillonite, kaolinite, chlorite and illite in shales and slates. (2) Water-weakening effect is more distinctive when clay minerals array in order than in disorder. (3) Hydration progress of shales and slates happens in a gradual course. That is to say, clay minerals on the surface absorbed water and expanded firstly, which made the shale and slate fallen；then fluids filtered into the rock inside along the layer surfaces or cracks with time prolonged, and the inner minerals expanded, which made the fall occurred when without confining pressures. (4) During hydration progress, addition of inorganic chemical components in slurry and pressure increase will constrain the water-weakening effect; while the temperature will accelerate the water-weakening rate.