Effect of naphthalene dispersant on the hydration kinetics of cement slurry: Nuclear magnetic resonance-based investigation

Cementing technology can effectively extend the life of coalbed methane surface drilling. The fluidity of the cement slurry during cementing is critical to the cementing quality. It is an effective way to improve the cementing quality by increasing the fluidity and pumping efficiency of cement paste by adding dispersants. In this paper, the effect of naphthalene dispersant on the hydration kinetics of G-grade cement was investigated by nuclear magnetic resonance. The results show that the increase of naphthalene dispersant mass fraction can effectively slow down the hydration of cement. The first relaxation peak of cement is correlated with its mobility, and the calculation of its peak index, area size, area share and combined action factor can be used to evaluate the retarding and dispersing effect of naphthalene dispersant on cement slurry more accurately. The main effects of naphthalene dispersant retarding and dispersing are: naphthalene dispersant causes an increase in xi potential of cement particles, which makes the potential barrier overcome by cement particle coalescence rise; the sulfonic acid group of naphthalene dispersant can form a more stable complex with Ca2+ , resulting in a reduced hydration rate. Naphthalene dispersant can decompose in cement into anions adsorbed on the surface of cement particles, forming a solvation film and producing a lubricating and dragging effect. The obtained research results provide theoretical support for the prepa-ration and pumping of on-site cementing slurry from three aspects: the fluidity of the naphthalene dispersant modified cement slurry, the retarding effect and how to choose the pumping period. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Cementing technology is crucial for prolonging the life of coalbed methane surface drilling. Adding dispersants can enhance the fluidity and pumping efficiency of cement paste, thus improving the cementing quality. Research on the effect of naphthalene dispersant on the hydration kinetics of G-grade cement shows that it can effectively slow down the cement hydration process by affecting the cement particle potential and forming stable complexes with Ca2+ ions.