FIELD: chemistry.
SUBSTANCE: disclosed are methods of controlling polymer depolymerisation rate in a working fluid containing a biocide, involving the preparation of an aqueous mixture comprising a depolymerisation inhibitor containing hydroquinone, ascorbic acid, isoascorbic acid or a combination thereof, and a biocide selected from tris(hydroxymethyl)phosphine or a water-soluble tetrakis(hydroxymethyl)phosphonium salt, contacting said mixture with a working fluid comprising a polymer providing a power supply for bacteria populations selected from a natural polymer which is a polysaccharide, or a synthetic polymer which is polyacrylamide or a copolymer of polyacrylamide and acrylic acid, wherein the biocide when used in an amount effective to reduce the content of bacteria causes depolymerisation of the polymer in the working fluid. Disclosed are novel efficient methods of controlling polymer depolymerisation rate in a working fluid containing a biocide with a stable viscosity, as well as a composition containing a tetrakis(hydroxymethyl)phosphonium salt of 5 to 85 %, a depolymerisation inhibitor selected from hydroquinone, ascorbic acid, isoascorbic acid or a combination thereof from 0.01 to 50 % of the weight of the composition and, optionally, water, to reduce content of bacteria in working fluids of an oil-field facility, and maintain their stable viscosity, improve properties of reducing friction in a biocidal-containing working fluid.
EFFECT: present invention relates to methods of controlling depolymerisation of polymer in a working fluid containing a biocide and compositions for adding to working fluids which can be used in oil industry.
31 cl, 2 ex, 2 tbl, 1 dwg
