Methods and compositions related to gelled layers in oil and/or gas wells
Methods and compositions for the prevention of the formation, breakdown, and/or removal of gelled layers in an oil and/or gas well are provided. In some embodiments, the compositions and methods comprise a concentrate, as described in more detail herein, where the concentrate comprises two or more surfactants. In certain embodiments, the compositions and methods comprise an emulsion or a microemulsion. The emulsion or microemulsion may include a surfactant, optionally a solvent, and optionally a freezing point depression agent or other components.
1. A method of breaking down a gelled layer in an oil or gas well having a wellbore, comprising:
injecting at least a concentrate comprising a first type of surfactant and a second type of surfactant into the wellbore,
wherein the first type of surfactant comprises an ethylene oxide/propylene oxide block copolymer;
wherein the second type of surfactant comprises an ethoxylated quaternary ammonium compound;
wherein the wellbore comprises the gelled layer; and
wherein the gelled layer comprises a partially broken crosslinked guar polymer; and
breaking down the gelled layer.
2. The method according to claim 1 , wherein the concentrate is combined with a first type of dilution fluid during the injecting step to form a concentrate solution.
3. The method according to claim 2 , wherein the first type of dilution fluid comprises a freezing point depression agent.
4. The method according to claim 3 , wherein the freezing point depression agent is present in the first type of dilution fluid in an amount between about 0 wt % and about 80 wt %.
5. The method according to claim 2 , wherein the pH of the first type of dilution fluid is about neutral or greater.
6. The method according to claim 2 , wherein the first type of dilution fluid comprises a base.
7. The method according to claim 6 , wherein the base is present in the first type of dilution fluid in an amount between about 1 wt % and about 60 wt %.
8. The method according to claim 6 , wherein the base comprises potassium chloride.
9. The method according to claim 2 , wherein the first type of dilution fluid comprises an aqueous phase.
10. The method according to claim 9 , wherein the aqueous phase comprises water.
11. The method according to claim 9 , wherein the aqueous phase is present in the first type of dilution fluid in an amount between about 1 wt % and about 90 wt %.
12. The method according to claim 2 , wherein the first type of dilution fluid comprises a salt.
13. The method according to claim 1 , wherein the concentrate is combined with a second type of dilution fluid during the injecting step.
14. The method according to claim 1 , wherein each of the first type of surfactant and the second type of surfactant are individually present in the concentrate in an amount between about 1 wt % and about 100 wt %.
15. The method according to claim 1 , wherein the crosslinked guar polymer comprises a borate crosslinker.
16. The method according to claim 1 , wherein the concentrate comprises a breaking additive.
17. The method according to claim 16 , wherein the breaking additive comprises ammonium persulfate.
18. The method according to claim 1 , wherein the concentrate does not comprise an emulsion or a microemulsion.