CEMENT SLURRY FOR CEMENTING OIL AND GAS WELLS Russian patent published in 2015 - IPC C09K8/467 

FIELD: oil and gas industry.

SUBSTANCE: cement slurry for cementing oil and gas wells consists of Portland cement, penetrating agent, fluid loss reducing agent, plasticising agent, antifoaming agent and water and differs in the fact that its contains PenetronAdmix as penetrating agent, any water-soluble cellulose ester as fluid loss reducing agent, lignosulphonate as plasticising agent, tributyl phosphate as antifoaming agent with the following ratio of components, wt %: Portland cement - 100, the above penetrating agent 3.0 in excess 100, the above fluid loss reducing agent - 0.03-0.1 in excess 100, the above plasticising agent - 0.3-0.7 in excess 100, tributyl phosphate - 0.01-0.1 in excess 100, water up to water-cement ratio - 0.38-0.42.

EFFECT: recovering integrity of cement sheath in annular space of wells when microcracks and microgaps are formed in it.

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