EXPANDING BACKFILL MATERIAL FOR LOW-TEMPERATURE WELLS Russian patent published in 2024 - IPC E21B33/138 C09K8/467 

FIELD: chemistry.

SUBSTANCE: invention relates to cementing of casing strings in gas, gas condensate and oil wells, namely to backfill materials used at low temperatures, permafrost and loose rocks. Expanding backfill material contains 55.2–70.7 wt. % of backfill portland cement, 10.0–15.0 wt. % of lightweight additive in form of expanded-clay dust with specific surface area of 550–650 m²/kg, 7.0–10.0 wt. % of expanding component in form of sulphoaluminate-belite binder SABV-30-1, 10.0–15.0 wt. % of a binding component, a structure-forming agent and a thickening-setting time regulator in the form of aluminium hydroxochloride. Material additionally contains 2.0–4.0 wt. % aluminosilicate microspheres, 0.3–0.8 wt. % of superplasticizer in form of powder product based on modified polyester carboxylate Melflux 1641 F, fresh or stratum water in excess of 100 wt. %, with water-mixture ratio (W/M) equal to 0.5–0.7.

EFFECT: improving the quality of primary cementing of casing strings and isolation of formations in conditions of low temperatures due to elimination of oil-water and gas shows and inter-string pressures.

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