硅溶胶在固井水泥浆中的应用性能研究

对比分析了添加硅溶胶前后固井水泥浆性能的变化,以此获得硅溶胶的作用特点,为硅溶胶的推广应用提供理论依据和实验基础.结果表明,水灰比为0.44时,添加1.0%的硅溶胶就能明显改善浆体的稳定性;水灰比为0.75时,添加4.0%的硅溶胶可得到1.60 g/cm3的低密度水泥浆.随后利用ATR-IR、XRD、DSC-TG、SEM等手段分析水泥水化产物,结果表明:硅溶胶具有火山灰的作用,添加量为1.0%时已具有较明显的促凝、增加抗压强度及降低渗透率的作用;同时,它还具有一定的防高温衰退作用,在127℃单独添加1.0%的硅溶胶或在165℃将1.0%的硅溶胶与15.0%的硅粉混合使用,养护3 d后均没有明显的水泥石强度衰退发生.

Study on the performance of colloidal silica for cementing slurry

In order to obtain the effect of colloidal silica to cementing slurry,the performance of the cementing slurry without and with colloidal silica is compared and analyzed.The results show that: when the colloidal silica of 1.0 %(mass fraction) is added in the cementing slurry with the water-to-cement mass ratio of 0.44,the stability of the cementing slurry can be significantly improved;the low density cementing slurry of 1.60 g/cm3 can be obtained when the colloidal silica of 4.0 %(mass fraction) is added in the cementing slurry with the water-to-cement mass ratio of 0.75.The cement hydration products are examined with ATR-IR,XRD,DSC-TG,it is shown that colloidal silica has the effect of volcanic ash: the colloidal silica of 1.0 % can promote the solidification of cementing slurry,increase its compressive strength and decrease its permeability;the colloidal silica of 1.0 % being added alone at 127 ℃ or the colloidal silica of 1.0 % and the silica flour of 15.0 % being added at the same time at 165 ℃,the strength of the cement does not decline after 3 days.The study results in this paper can provide the basis for the application of colloidal silica in cementing slurry.