PERACETIC ACID OIL-FIELD BIOCIDE AND METHOD
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.
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.