EXPANDABLE CEMENT COMPOSITION AND METHOD FOR ITS APPLICATION FOR CEMENTING UNDERGROUND WELL WITH CASING Russian patent published in 2023 - IPC C09K8/467 C04B28/02 E21B33/14 

FIELD: oil and gas wells construction.

SUBSTANCE: expandable cement composition and a method for cementing an underground well with a casing. Expandable cement composition consists of a solid-phase expander of the oxide and/or compression type, a polymeric additive, dry cement in the following ratio of components by weight of dry cement, %: solid-phase expander of the oxide and/or compression type 0.1-30; polymer additive 10-50; dry cement - the rest, while the ratio of solid-phase expanding additives of oxide and compression types is regulated as follows: at a static temperature at the bottom hole in the range from 5°C to 49°C using a solid phase oxide type expander, at a static bottom hole temperature in the range of 50°C to 65°C, a combination of solid-phase expanders of oxide and compression types is used, at a static bottom hole temperature of more than 66°C using compression type solid phase expander . An expandable cement slurry and a method for cementing an underground well with a casing are also claimed.

EFFECT: increase in the linear expansion of the expandable cement slurry during hardening, an increase in compressive strength and a decrease in the Young's modulus of the cement stone formed during hardening from the expandable cement slurry.

18 cl, 2 tbl