油井水泥缓凝剂BH作用机理研究

Study on Working Mechanism of Oil Well Cement Retarder BH

通过XRD、能谱分析、络合滴定、SEM等方法,研究了油井水泥水化过程诱导期的反应机理及实验室自制缓凝剂BH(长支链的羧酸、磺酸型)对水泥水化过程诱导期的影响。水泥熟料水化初期,体系中Ca(OH)2含量为2%左右,诱导期结束后,Ca(OH)2含量最大可升至45%。结果表明,水化过程诱导期主要受溶液中Ca(OH)2含量的影响。缓凝剂BH能牢固地吸附到水泥颗粒表面形成包覆层,阻止水泥的进一步水化,同时能够与Ca2+络合,增加Ca(OH)2过饱和溶解度至1.97 g/m L,抑制Ca(OH)2晶核的形成,延长了水泥浆的诱导期。从电镜图可以看出,BH能改变Ca(OH)2晶体的晶貌,抑制晶体生长,从而在一定程度上延长了水泥的稠化时间,达到了缓凝目的。

The reaction mechanism of the hydration process of oil well cement in induction period,and the effect of an oil well cement retarder,BH,（a long branched chain carbonic acid,sulfonic acid） on the induction period were studied through a series of laboratory experiments.Ca（OH）_2 content in the cement clinker at the early hydration stage was about 2%,and went up to 45%at the end of the induction period.This indicates that the induction period is controlled by the concentration of Ca（OH）_2 in the liquid phase.BH can be adsorbed fast on the surface of cement particles to form a wrapping layer,retarding further hydration of cement.The complexion of Ca^（2＋） by BH increased the super-saturation solubility of Ca（OH）_2 to 1.97 g/mL,inhibiting the formation of Ca（OH）_2 crystal nucleus and prolonging the induction period of the cement slurry.SEM charts show that BH changed the appearance of the Ca（OH）_2 crystals and inhibited its growth,further prolonging the thickening time,and retarding the hydration of cement.