砂层冻结过程中未冻水含量核磁共振实验研究

Nuclear Magnetic Resonance Test Study of Unfrozen Water Content in the Process of Sand Freezing

为探究砂层冻结过程中未冻水含量随温度变化的规律,采用低场核磁共振法对不同含水率砂层的未冻水变化规律进行研究,并结合T_(2)谱曲线分析了砂层冻结过程中未冻水在砂层孔隙中的分布情况。研究结果表明:当砂体初始含水率较低时,砂体中的水主要赋存于颗粒表面的微小孔隙;砂体中的结合水含量达到一定值后,基本保持不变,而增加的大部分水为储存于中等、较大孔隙中的自由水;多孔介质的冻结温度(冰点)为-2.0~-0.5℃,相变区间、未冻水含量随砂层初始含水率的增大而增大。

In order to explore the change rule of unfrozen water content with temperature during freezing,low-field nuclear magnetic resonance technology is used to study the change rule of unfrozen water in sand with different moisture content,and the distribution of unfrozen water in sand pores during freezing is analyzed by combining T_(2) spectrum curve.The results show that when the initial water content is low,the water in the porous medium mainly exists in the micro pores on the particle surface.The content of bound water in porous media is basically unchanged after reaching a certain value,while most of the increased water is stored in medium and large pores as free water.The freezing temperature(freezing point)range of porous media with different initial water content is-2.0~-0.5℃,the phase transformation interval increases with the increase of initial water content,and the unfrozen water content also increases with the increase of initial water content.