METHOD AND COMPOSITION TO CLEAN BOREHOLE PRIOR TO CEMENTING Russian patent published in 2011 - IPC C09K8/40 C09K8/52 E21B37/06 

FIELD: construction.

SUBSTANCE: composition of a spacer fluid for cleaning of a borehole prior to cementing includes at least one alkyl ether of citric acid with common formula and/or where x makes 1-20, m makes 1-50 and n makes 0-10, and additionally at least one alcohol ethoxylate of common formula IV: CH₃(CH₂)_x(C₂H₄O)_m(C₃H₆O)_nOH, where x makes 1-20, m makes 1-50 and m makes 0-10, where the specified at least one alkyl ether of citric acid is used in the specified spacer fluid in concentration from approximately 0.5% in weight to approximately 10% in weight on the basis of 100% active substance, and combination of the specified at least one alkyl ether of citric acid and the specified at least one alcohol ethoxylate is used in the composition of the spacer fluid in concentration from approximately 1.0% in weight to approximately 5% in weight on the basis of 100% active substance. In the method of cleaning a part of the borehole wall, prior to cementing, the specified above composition is used.

EFFECT: improved binding of cement with a casing string and a well wall.

15 cl, 3 ex, 1 dwg