水泥外掺料粉煤灰活性激发剂试验研究

粉煤灰能提高和改善水泥性能,特别是能有效地降低水泥的水化热。粉煤灰作为外掺料加入油井水泥中,虽然水泥石后期强度较高,但其早期水化活性很低,温度较低时甚至几乎没有活性可言,随着粉煤灰的掺量增加,水泥石早期强度急剧下降,致使粉煤灰在油井固井中受到严格限制。原因是,粉煤灰本身不能单独进行水化反应产生强度,需要激发剂激发其活性,粉煤灰的研究关键在于其活性激发剂的研究。因此,在室内进行了大量实验,实验证明:以无机盐复配的活性激发剂J-1,能有效地激发粉煤灰的活性,可使粉煤灰与水泥掺入量达到1:1以上,应用于表层固井可用到接近2:1,且保持较高的早期强度,同时,可使水泥石膨胀,提高界面胶结强度,有一定的防窜能力,另外,粉煤灰的颗粒较水泥大,对堵漏有一定贡献。

Experimental research on cement mixed with fly ash reactive activator

Fly ash can be used to improve the performance of cement,especially to effectively reduce the total heat of hydration in cement.Although the post-strength of cement is high,it has low hydration activity in early stage.When the temperature is low,the cement has no activity at all.If more fly ash is added,the post-strength of the cement will decrease dramatically and the fly ahs will be strictly restricted in oil well cementing.Since there is no hydration reaction between fly ash and no strength is generated,so activator needs to be used to activate its activity.The key to research fly ash is to study its reactive activator.So a lot of lab test are conducted.Results show that J-1,a reactive activator in combination of inorganic salts,can effectively activate the activity of fly ash.It enables the ratio of fly ash to cement mixed to reach more than 1:1,and it may be close to 2:1 if being applied to surface cementing.The early strength of fly ash can be kept high.Meanwhile,the cement will be expanded to enhance the interface cementing strength.What’s more,the particles of fly ash are bigger than those of cement,which is favorable for sealing.