Regulation of oil well cement paste properties by nanoclay: Rheology, suspension stability and hydration process

Enhanced grid reconstruction ability of oil well cement paste has been confirmed as a promising solution to inhibit particle sedimentation caused by the uncontrolled rheological property at high temperatures. The effect of nanoclay dispersions of Bentonite and Laponite on the rheological property, suspension stability and hydration process of the cement pastes was examined. The nanoclay dispersions (especially Laponite) enhanced the dynamic reversible gel structure and improved its reconstruction ability. The addition of nanoclay effectively inhibited the sedimentation of solid particles at high temperatures due to form a gel structure by polymer admixtures, nanoclay and cement colloidal particles. Moreover, the nanoclay facilitated the cement hydration and enhanced the mechanical property for the nucleation and filler effect. Accordingly, the nanoclay can enhance thixotropy and suspension stability of the early cement paste and increase the mechanical strength of hardened cement stones, which contributes to improving the sealing integrity of cement sheath.