固井低密度水泥浆用矿渣和粉煤灰反应活性对比

Comparison with Hydration Activity of Slag and Fly Ash Used in Low-Density Cement Slurry

矿渣低密度水泥浆和粉煤灰低密度水泥浆在油田固井作业中应用广泛,对解决低压易漏失地层固井和提高固井作业质量及经济效益具有重要意义。文章研究了50℃下矿渣和粉煤灰对低(1.50 g/cm~3)密度水泥浆体早期抗压强度的影响。水化热(ICC)测试表明,50℃下矿渣低密度水泥浆水化速率峰值及1 d累计放热量较粉煤灰低密度水泥浆分别增大16.7%和14.1%。水化产物定性及定量分析观察表明,1 d龄期矿渣低密度水泥石中存在大量絮状产物C-S-H凝胶,并伴有AFt和Ca(OH)_2晶体生成,且随水化反应进行AFt含量增加,养护10 d后部分AFt转化为AFm。粉煤灰低密度水泥石中C-S-H凝胶和AFt含量从1 d至7 d逐渐增加。随着养护龄期延长,两种低密度水泥石基体逐渐密实,水泥石抗压强度都逐渐增大,但矿渣的早期水化反应活性高于粉煤灰,使得矿渣低密度水泥石早期抗压强度高于粉煤灰低密度水泥石。

The slag low-density cement slurry and fly ash low-density cement slurry are widely used in oil well cementing,they are of great significance to solve the low pressure and easy leakage formation well cementing and improve the quality and economic benefit of well cementing.In this paper,the effects of two mineral admixtures,slag and fly ash,on the early compressive strength of 1.50 g/cm3 cement slurry at 50℃were studied and characterized by hydration exothermic(ICC),hydration products and scanning electron microscopy(SEM).The ICC tests showed that the peak of hydration rate and cumulative heat release in 1 d of slag low-density cement slurry at 20°C were 16.7%and 14.1%higher than that of fly ash low-density cement slurry,respectively.XRD and SEM tests showed that there was a large amount of flocculent product C-S-H gel in slag low-density cement stone after curing 1 d,and accompanied by the formation of AFt and Ca(OH)2 crystals.Thecontent of AFt increased with the hydration reaction,part of AFt converted to AFm after curing 10 d.The content of C-S-H gel and AFt in fly ash low-density cement stone increased from 1 d to 7 d.With the prolongation of curing age,the matrix of slag low-density cement stone and fly ash low-density cement stone gradually became compacted,and the compressive strength of cement stone gradually increased.The results showed that the hydration reaction activity of slag was higher than that of fly ash,which made the early compressive strength of the slag low-density cement stone is higher than that of the fly ash low-density cement stone.