Peracetic acid oil-field biocide and method

Abstract

Aqueous well treatment fluid compositions with biocidal activity are disclosed comprising a polymer for modifying fluid viscosity in the aqueous fluid, an organic monocarboxylic peracid being present in an anti-microbial amount of about 1 ppm to about 1000 ppm, and a controlled amount of hydrogen peroxide also being present. Peracetic acid is the preferred peracid. The viscosity-modifying polymer in the aqueous well treatment fluid composition may serve to reduce friction in the fluid or increase fluid viscosity. A method of using such compositions is also disclosed.

What is claimed is: 
     
         1 . An aqueous well treatment fluid composition with biocidal activity comprising
 a polymer or copolymer for modifying fluid viscosity;   an organic monocarboxylic peracid in an antimicrobial amount of about 1 ppm to about 1000 ppm; and   hydrogen peroxide, the hydrogen peroxide concentration being less than the peracid concentration;   in an aqueous medium.   
     
     
         2 . The composition of  claim 1  wherein the peracid is a C 2  to C 5  peroxycarboxylic acid. 
     
     
         3 . The composition of  claim 2  wherein the peracid is selected from peracetic acid and perpropionic acid. 
     
     
         4 . An aqueous well treatment fluid composition with biocidal activity comprising
 a fluid viscosity-reducing polymer or copolymer in a friction-reducing amount to provide improved fluid flow characteristics;   peracetic acid in an antimicrobial amount of about 1 ppm to about 1000 ppm; and   hydrogen peroxide, the hydrogen peroxide concentration being less than the peracetic acid concentration;   in an aqueous medium.   
     
     
         5 . The composition of  claim 4  wherein the peracetic acid is present in an amount of about 1 ppm to about 50 ppm. 
     
     
         6 . The composition of  claim 4  wherein the polymer or copolymer is selected from the group consisting of acrylamide-derived polymers and copolymers; acrylate-derived polymers and copolymers; guar and guar derivatives; ethylene oxide-derived polymers, and combinations of these. 
     
     
         7 . The composition of  claim 4  wherein the friction-reducing polymer or copolymer is present in an amount of about 0.01 wt % about 1 wt %, based on the weight of the aqueous composition. 
     
     
         8 . The composition of  claim 4  wherein the aqueous well treatment fluid composition is a slick water composition, containing an acrylamide-derived polymer or copolymer that functions as a friction reducer to improve the flow characteristics of the aqueous fluid composition. 
     
     
         9 . An aqueous well treatment fluid composition with biocidal activity comprising
 a viscosity-increasing polymer or copolymer in an amount sufficient to increase fluid viscosity;   peracetic acid in an antimicrobial amount of about 1 ppm to about 1000 ppm; and   hydrogen peroxide, the hydrogen peroxide concentration being less than the peracetic acid concentration;   in an aqueous medium.   
     
     
         10 . The composition of  claim 9  wherein the peracetic acid is present in an amount of about 1 ppm to about 100 ppm. 
     
     
         11 . The composition of  claim 9  wherein the viscosity-increasing polymer or copolymer is selected from the group consisting of acrylamide-derived polymers and copolymers; acrylate-derived polymers and copolymers; natural and synthetic polysaccharides and their derivatives; natural and synthetic cellulosic polymers and copolymers and their derivatives; and combinations of these. 
     
     
         12 . The composition of  claim 11  wherein the viscosity-increasing polymer or copolymer is at least partially crosslinked. 
     
     
         13 . The composition of  claim 9  wherein the viscosity-increasing polymer or copolymer is present in an amount of about 0.01 wt % to about 10 wt %, based on the weight of the aqueous composition. 
     
     
         14 . A method of providing biocidal activity in a well treatment fluid comprising introducing, into an aqueous well treatment fluid composition comprising
 a polymer or copolymer for modifying fluid viscosity, and an aqueous monocarboxylic peracid solution in an antimicrobial-effective amount of about 1 ppm to about 1000 ppm, the aqueous peracid solution having a peracid acid weight concentration in excess of hydrogen peroxide also present in the aqueous peracid solution; and thereafter directing the aqueous well treatment fluid into a subterranean environment.   
     
     
         15 . The method of  claim 14  wherein the peracid is a C 2  to C 5  peroxycarboxylic acid. 
     
     
         16 . The method of  claim 15  wherein the peracid is selected from peracetic acid and perpropionic acid. 
     
     
         17 . The method of  claim 14  wherein the peracid is present in an amount of about 1 ppm to about 50 ppm. 
     
     
         18 . The method of  claim 14  wherein the peracid is introduced into the aqueous well treatment fluid composition when the composition has a pH less than about 8. 
     
     
         19 . The method of  claim 14  wherein the peracid is introduced into water used to prepare the aqueous well treatment fluid composition. 
     
     
         20 . The method of  claim 14  wherein the polymer or copolymer serves to reduce fluid viscosity and is present in a friction-reducing amount to provide improved fluid flow characteristics. 
     
     
         21 . The method of  claim 20  wherein the polymer or copolymer is selected from the group consisting of acrylamide-derived polymers and copolymers; acrylate-derived polymers and copolymers; guar and guar derivatives; ethylene oxide-derived polymers, and combinations of these. 
     
     
         22 . The method of  claim 20  wherein the friction-reducing polymer or copolymer is present in an amount of about 0.01 wt % about 1 wt %, based on the weight of the aqueous composition. 
     
     
         23 . The method of  claim 14  wherein the polymer or copolymer serves to increase fluid viscosity and is present in an amount sufficient to provide increased fluid viscosity. 
     
     
         24 . The method of  claim 23  wherein the viscosity-increasing polymer is selected from the group consisting of acrylamide-derived polymers and copolymers; acrylate-derived polymers and copolymers; natural and synthetic polysaccharides and their derivatives; natural and synthetic cellulosic polymers and copolymers and their derivatives; and combinations of these. 
     
     
         25 . The method of  claim 24  wherein the viscosity-increasing polymer is viscosity-increasing polymer or copolymer is at least partially crosslinked. 
     
     
         26 . The method of  claim 23  wherein the viscosity-increasing polymer is present in an amount of about 0.1 wt % to about 10 wt %, based on the weight of the aqueous composition.