DISPLACEMENT FLUID Russian patent published in 2003 - IPC

FIELD: oil and gas well casing and cementing. SUBSTANCE: displacement fluid contains, wt.%: water-soluble polyphosphates or their mixture, and/or alkali metal metaphosphate, 0.05-3.0; oxyethylated alkyl phenol with oxyethylation degree of 9-25, 0.3.0; sodium sulfate, 0.05-3.0; water, the balance. Displacement fluid may contain water-soluble polyphosphate in the form of pyrophosphate or tripolyphosphate. Metaphosphate is used in the form of hexametaphosphate. EFFECT: increased quality of well cementing due to increased washing ability of displacement fluid and stability of washing action under conditions of clay saturation and increased sealing of cement stone-casing contact. 2 cl, 2 tbl, 1 ex