VISCOELASTIC COMPOSITION FOR TEMPORARY ISOLATION OF PRODUCTIVE FORMATIONS Russian patent published in 2016 - IPC C09K8/42 E21B33/138 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to process compositions used for completion, development, overhaul and routine maintenance of wells for temporary isolation of productive beds in the process of killing of wells with normal and abnormally low formation pressures. Viscoelastic composition (VEC) includes an aqueous solution of a polymer of polysaccharide nature, carbamide and calcium carbonate as activators of polymer cross-linking, a cross-linking agent -for formation of intermolecular spatial structure, a decomposer - for self-destruction of gel after a given time interval, a water-soluble salt of monovalent metal for increase in density of the composition with the following proportions, MP: biopolymer (xanthan gum) - 0.8-1.3; carbamide (urea) - 0.4-0.6; calcium carbonate (marble chips) - 1.4-2.3; acetic chrome, aqueous solution - 0.4-0.7; ammonium sulfate - 0.025-0.125; fresh water or solution of monovalent metal salts (sodium, potassium) of required density - the rest.

EFFECT: higher technological effectiveness of using the composition due to optimisation of gel formation time, improvement of structural-mechanical and insulating properties, reduction of negative effect of filtrate on productive formation due to reduction of filtration index, controlled time of composition destruction.

1 cl, 3 tbl