用红外光谱法确定粘土表面结合水界限

针对泥页岩吸附结合水诱发或加剧井壁不稳定问题,采用红外光谱法对粘土表面结合水界限进行了定性确定,同时获得有关水分子中化学键合及水分子与粘土矿物间相互作用的信息。结果表明,粘土矿物能与水相互作用而吸附结合水,随着粘土吸附结合水量增多,水合蒙脱土中水分子的伸缩振动频率ν随之降低。在伸缩振动频率ν随相对水气平衡压p/ps的变化过程中,存在先快、中间慢、后期又快直至稳定的特点,出现两个明显的转折点p/ps=0.9、0.98,它们为粘土—水体系的两个特征湿度,前者为粘土表面强结合水与松散结合水(渗透结合水)之间的交界点(界限),后者为松散结合水(渗透结合水)与自由水之间的交界点(界限)。其结果与离子交换法获得的结果相一致。

THE DETERMINATION OF BOUND WATER BOUNDARY ON CLAY SURFACE BY INFRARED SPECTRUM

In accordance with wall of well-bore instability induced by bound water on clays, Infrared spectrum is utilized to determine the types and boundary line of bound water on clays, and the information about chemical-bonding in water and interaction between water and clay-mineral. The results show thatclay-minerals adsorb water when they interact with water.The O-H's expanded and contracted frequency v will reduce along with adsorbed water content growth in hydro-clays.Theprocess that O-H's expanded and contracted frequency vchanges along with relative vapor pressure p/pshas the charac-teristics - fast first, slow then, fast again, and steady forever.There are two clear turning points which are p/ps=0.9, 0.98,the two turning points are the special humidity of clay-water system. The relative vapor pressure 0.9 is the boundary line between the strong bound water and the loose bound water(osmotic bound water) on clays, the relative vapor pressure 0.98 is the boundary line between the loose bound water and free water on clays. The results are identical with Ion exchange.