GAS-CEMENT BACKFILL COMPOSITION Russian patent published in 2019 - IPC C09K8/473 E21B33/138 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, in particular to backfill compositions used for cementing casing strings in oil, gas and gas condensate wells. Technical result of claimed invention is achieved due to increase in gas release onset time and its duration, creation of stable gas-saturated system capable to maintain constant pore pressure in annular space, which makes it possible to prevent ingress of formation fluids into the hardening grouting mortar during the period of the backfill system transition from the solution to the stone, and in the subsequent formation of impermeable stone. Gas-cement backfill composition contains oil well cement, salt additive, non-ionic surfactant, polymer stabilizer reagent, gas-forming additive, regulator of beginning and duration of gas release, superplasticizer and water in following ratio of components, pts.wt: oil well cement 100.0, salt additive 2.0–8.0, non-ionic surfactant 0.05–0.20, polymer stabilizer reagent 0.1–0.3, gas-forming additive 0.05–0.20, regulator of beginning and duration of gas release 0.1–0.3, superplasticizer 0.05–0.15, water 45.0–60.0. As a salt additive plugging composition contains calcium chloride, as non-ionic surfactant contains oxyethylated monoalkylphenol based on propylene trimers Neonol AF 9-4, polymer stabilizer reagent contains a non-ionic mark of hydroxyethylcellulose Natrosol 250 MX, as gas-forming additive contains aluminum powder PAP-2, as a regulator of the beginning and duration of gas release contains citric acid, as a superplasticizer contains a reagent based on melamine sulphonate NTPF-17. Formation of high-strength stone, required degree of isolation of productive strata in cementing interval.

EFFECT: high insulating capacity of gas-cement backfill composition.

1 cl, 1 tbl