Patent ID: 11965130
Assignee: NISSAN CHEMICAL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  E  Y | IPC C

Claim 0:
1. An additive for cement slurry for a well, comprising:
an aqueous dispersion of colloidal silica particles having an average particle size of 3 to 200 nm by a dynamic light scattering method; and
a dispersion stabilizer consisting of at least one compound having an alcoholic hydroxyl group selected from the group consisting of methanol, ethanol, isopropyl alcohol, ethylene glycol, diethylene glycol, propylene glycol, and glycerin, optionally in combination with a water-soluble primary, secondary or tertiary amine, wherein
the additive for cement slurry for a well comprises 1 to 30 mol of the compound per 1000 g of a dispersion medium in the aqueous dispersion of the colloidal silica particles,
in the case of retaining the additive for cement slurry for a well at −20° C. for 48 hours and subsequently measuring an average particle size by the dynamic light scattering method at +20° C., the average particle size falls within a range of 1.0 to 7.0 times the initial average particle size before the retention, and
in the case of retaining the additive for cement slurry for a well at +50° C. for 7 days and subsequently measuring an average particle size by the dynamic light scattering method at +20° C., the average particle size falls within a range of 1.0 to 7.0 times the initial average particle size before the retention.