Abstract: Using Blast Furnace Slag (BFS) to convert drilling fluid into cementing fluid system (MTC) mainly exists two limitations in producing application: one is it has less antiseepage ability, second is the strength regression of solid state under high temperature (T>70℃). Through SEM analysis the main reason of strength regression of BFS solid state under high temperature is due to the uneven growth of crystallization of hydrates of silicon calcic rock and calcium alumna rock and finally occurs under the high stress condition at the later period of solid state. After applying hydrated heat analysis, contract rate test, permeability test, analysis of strength increase curve, regular physical test and microstructure analysis to BFS, the strength increase and elastic increase of BFS solid state were improved by the crystal kern induced and thus propose a theory that crystal kern induced mechanism of BFS system is a part chemical of kern forming of heterogeneity phase. The microfracture in the BFS solid state induced by crystal kern could be closed, the gas permeability is lower than 1×10^-3umsup>2.After BFS solid state have been maintained in water bath of 75℃ for half year, the compression strength is higher than 25MPa, with no strength regression phenomenon.

Key words: slag cement, strength, elasticity, crystal grain, permeability, microfracture, hydrated mineral

摘要： 利用高炉矿渣(简称BFS)将钻井液转化成固井液体系(简称MTC)在生产应用中主要存在着两方面的局限性:一是抗渗性较差,二是固化体在高温(>70℃)下强度衰退.通过SEM分析,得出BFS固化体高温条件下强度衰退主要原因是由于硅钙石和钙矾石两种水化产物结晶发育不一致,固化体后期处于高应力状态而产生的.进行了水化热分析、收缩率实验、渗透率实验、强度增长曲线分析、常规物性实验及显微结构分析等实验研究,从而得出晶核诱导剂能改善BFS固化体的强度增长和弹性增长,指出BFS体系晶核诱导机理是非均相成核的局部化学反应.晶核诱导的BFS固化体内部微裂缝能够闭合,气体渗透率低于1×10^-3μm².BFS固化体在75℃水浴中养护半年后,抗压强度大于25MPa,无强度衰退现象.

关键词: 矿渣, 强度, 弹性, 晶核, 渗透率, 微裂隙, 水化产物