Preparation, characterization, and evaluation of suspension stabilizer for low‐density cement slurry for cementing

Abstract

AbstractA low‐density cement slurry system is commonly used in low‐pressure and leakage‐prone cementing. However, the suspension stability of the system is more difficult to control because of the addition of lightning material. Especially under the condition of large temperature differences, the relative motion between solid particles with large density differences increases, which will aggravate the instability of the slurry and affect the cementing quality. Therefore, to effectively control the suspension stability of the low‐density cementing slurry system, the suspension stabilizer PAND was synthesized by free radical solution polymerization withN‐vinyl caprolactam (NVCL); 2‐acrylamide‐2‐methyl propane sulfonic acid (AMPS),N, N‐dimethyl acrylamide (DMAA) as monomers. The effect of PAND on the stability of low‐density cement slurry under a large temperature difference (40 ~ 120°C) was evaluated. The results showed that under 40 ~ 120°C, adding 0.8% PAND can control the water separation of the cement slurry to 0; the density difference between the upper and lower parts of the cement stone column after curing is less than 0.01 g/cm3. The mechanical properties of cement stone are improved, which shows that it has a good suspension stability effect on low‐density cement slurry systems. The analysis of UV spectroscopy and scanning electron microscopy showed that PAND formed an intermolecular hydrophobic association network structure with the increase in temperature, which could maintain the viscosity of the solution system, thus playing an influential suspension stability role.