MTA凝饼形成剂低温稳定性能的研究

Stability performance of MTA agglomerated cake forming agent at low temperature

关键词:  固井二界面  凝饼形成剂  溶质析晶  同离子效应  氢键作用 

Key words:  cement-formation interface  the agglomerated cake forming agent  solute crystallization  common-ion effect  hydrogen bonding

摘要:

MTA凝饼形成剂在低温环境中出现的析晶现象给MTA方法的推广和应用提出了新的挑战,充分认识MTA凝饼形成剂的低温稳定性能具有重要的理论意义和使用价值。通过单因素析晶对比试验可知,温度降低是溶质析晶出现的主要原因。通过离子色谱(IC)测试分析析晶前后阴离子浓度(主要是Cl-、NO₃-、SO₄2-)的变化,确定析出的晶体为十水硫酸钠。研究发现,GA-ⅠA溶液中同时存在同离子效应和氢键作用,其中同离子效应不利于硫酸钠溶液的稳定,而氢键作用则可以促进硫酸钠溶液的稳定,在一定条件下,两者相互作用处于一个动态平衡,共同影响MTA凝饼形成剂的低温稳定性能。 

Abstract:

The crystallization phenomenon of the MTA (mud cake to agglomerated cake) agglomerated cake forming agent at low temperature brings a new challenge to the popularization and application of MTA method. It is of great theoretical significance and use value to fully understand its stability performance at low temperature. The result of single factor comparative experiment showed that temperature decreasing was the main reason for the phenomenon of solute crystallization. The changes of anion concentration (such as Cl-,NO₃-,SO₄2-) before and after crystallization were analyzed by ion chromatography(IC), and the precipitated crystal was determined as sodium sulfate decahydrate. The research result showed that common-ion effect and hydrogen bonding coexist in GA-ⅠA solution. Common-ion effect was unfavorable to the stability of sodium sulfate solution, while hydrogen bonding was opposite. In certain condition, interaction between them was in dynamic equilibrium, which influenced simultaneously and mutually the stability performance of the MTA agglomerated cake forming agent at low temperature.