Method for down-hole treatment of a production well for sulfur based contaminants
In some embodiments, a method may include treating water comprising sulfur based contaminants. The method may include contacting a portion of water comprising a quantity of hydrogen sulfide with a first oxidant. The method may include producing sulfur solids as a result of contacting the hydrogen sulfide in the portion of water with the first oxidant. In some embodiments, the method may include separating the sulfur solids from the water. The first oxidant may include hydrogen peroxide. In some embodiments, oxidation of contaminated fluids may be accelerated by adding an acid in combination with a second oxidant to the contaminated fluids. In some embodiments, oxidation of contaminated fluids may be accelerated by adjusting a pH of the contaminated fluids after addition of an oxidant to the contaminated fluids. In some embodiments, the pH may be adjusted to less than 7.
1. A method for down-hole treatment of a production well for sulfur based contaminants, the method comprising:
providing a peracetate solution comprising:
peracetate anions;
a peracid;
a pH from about pH 10 to about pH 12; and
a molar ratio of peracetate anions to peracid ranging from about 60:1 to about 6000:1;
preparing outside of the well a treatment fluid, comprising combining the peracetate solution with a carrier fluid, wherein the treatment fluid comprises up to 1% by weight peracetate;
placement of a volume of the treatment fluid in the well in contact with surfaces in a portion of the well for treatment for the sulfur based contaminants;
after the placement, contacting the treatment fluid with the surfaces for a contact time while the well is off production; and
following the contact time, commencing production from the well.
2. The method of claim 1 , wherein the peracetate solution comprises a peracetate anion to hydrogen peroxide molar ratio of greater than about 16:1.
3. The method of claim 1 , wherein the at least some sulfur based contaminants comprise iron sulfides, hydrogen sulfide, or iron sulfide deposits.
4. The method of claim 1 , wherein:
the portion of the well comprises a production zone and the surfaces comprise surfaces of the production zone and/or production equipment positioned in the production zone.
5. The method of claim 1 , wherein the surfaces comprise surfaces of well casing.
6. The method of claim 1 , wherein the placement comprises displacement of well fluids from the portion of the well with the treatment fluid.
7. The method of claim 1 , wherein the carrier fluid comprises fresh water, salt water, or treated production water.
8. The method of claim 1 , wherein the treatment fluid further comprises a treatment additive selected from the group consisting of hydrochloric acid, citric acid, acetic acid, acid-containing micellar solvent, corrosion inhibitor, and iron chelant.
9. The method of claim 1 , wherein the well is a hydrocarbon production well, the method further comprising:
acid treating the production well in a treatment sequence before or after treatment with the treatment fluid.
10. The method of claim 1 , wherein the well is a hydrocarbon production well and the sulfur based contaminants comprise hydrogen sulfide from microbial activity, the method further comprising:
antimicrobial treatment of the surfaces with the treatment fluid during the contact time.
11. The method of claim 1 , wherein the well is a groundwater production well, the method further comprising:
antimicrobial treatment of the surfaces with the treatment fluid during the contact time to reduce populations of iron and sulfate reducing bacteria.
12. The method of claim 1 , further comprising killing hydrogen sulfide-producing bacteria in the portion of the well with the treatment fluid during the contact time.
13. The method of claim 1 , further comprising degrading and/or removing biofilms in the portion of the well with the treatment fluid during the contact time.
14. The method of claim 1 , wherein the placement comprises injecting the volume of the treatment fluid into the well and pushing the injected volume of the treatment fluid to the portion of the well with a second injection into the well of production water.
15. The method of claim 1 , further comprising, after the commencing production, separating at least some sulfur based contaminants from produced well fluids, wherein at least some of the sulfur based contaminants comprise products resulting from the reaction of sulfur based contaminants with the treatment fluid.
16. The method of claim 1 , wherein the portion of the well includes a production zone below a bottom end of a production tube in the well, and the method further comprising:
after the commencement of production, introducing a second volume of the treatment fluid into an annulus in the well between the production tube and well casing and circulating the second volume of the treatment fluid down the annulus and up through the production tube to treat the production tube while the well is on production.
17. The method of claim 16 , wherein the second volume of the treatment solution is freshly prepared during the contact time.
18. The method of claim 1 , wherein the peracetate comprises sodium peracetate.