CEMENTING COMPOSITION CONTAINING ANIONICALLY- AND HYDROPHOBICALLY- MODIFIED CELLULOSE ETHERS AND ITS USE Russian patent published in 2016 - IPC C09K8/467 E21B33/138 C04B24/38 

FIELD: construction.

SUBSTANCE: disclosed is a composition and method for cementing a casing in a borehole of a well using an aqueous cementing composition containing (a) water, (b) cementing composition containing: (i) hydraulic cement, (ii) anionically- and hydrophobically- modified polymer, (iii) dispersant and optionally (iv) one or more other additives, usually added to aqueous cementing compositions, suitable for cementing of casings in borehole of wells, wherein the anionically- and hydrophobically- modified hydroxyethyl cellulose has hydrophob degree of substitution of from 0.001 to 0.025, anionic degree of substitution of from 0.001 to 1, weight-average molecular weight of from 100,000 to 4,000,000 Daltons and it is preferable that dispersant is sulfonated polymer, melamine formaldehyde condensate, naphthalene formaldehyde condensate, branched or non-branched polycarboxylate polymer. Preferably, the aqueous cementing composition is pumped downwardly into said casing, pumping upwardly into the annulus, surrounding said casing until said aqueous composition fills that portion of the annular space desired to be sealed and then maintaining said aqueous cementing composition in place until cement sets. Invention is developed in subclaims of formula of invention.

EFFECT: technical result is reduced water loss, reduced time of pumping and reduced pressure caused by internal friction.

10 cl, 1 tbl