Breaker and displacement fluid
A breaker fluid for breaking a filtercake in a wellbore. The fluid including a hydrolysable ester of carboxylic acid, and a chelant, an alkyl glycoside, or a combination thereof. The breaker fluid may be pre-mixed and include an amount of water less than required to completely hydrolyze the ester.
1. A method of breaking a filtercake in a wellbore comprising:
preparing a pre-mixed breaker comprising:
a hydrolysable ester of carboxylic acid;
a chelant; and
an amount of water wherein the weight ratio of water to hydrolysable ester of carboxylic acid is less than 1.3 to 1;
combining the pre-mixed breaker with an aqueous fluid to form a breaker fluid prior to circulating the breaker fluid in the wellbore; and
contacting the filtercake in the wellbore with the breaker fluid.
2. The method of claim 1 wherein the pre-mixed breaker fluid comprises 0 wt % -10 wt % water.
3. The method of claim 1 wherein the hydrolysable ester of carboxylic acid is a formic acid ester of a C2 to C30 alcohol.
4. The method of claim 1 wherein the chelant comprises one or more chelants selected from a group consisting of: ethylenediaminetetraacetic acid; glutamic acid, N, N-diacetic acid; and salts thereof.
5. The method of claim 1 wherein the chelant comprises at least one iminodiacetic acid or a salt thereof, represented by the formula
wherein the M groups each independently represents a hydrogen atom, an alkali metal atom, an ammonium group or a substituted ammonium group; Y represents a divalent alkyl group having from 1 to 7 carbon atoms and the divalent alkyl group may be substituted by a hydroxyl group or a COOM group wherein M represents a hydrogen atom, an alkali metal atom, an ammonium group or a substituted ammonium group; and W represents a hydrogen atom, a hydroxyl group or a COOM group wherein M represents a hydrogen atom, an alkali metal atom, an ammonium group or a substituted ammonium group.
6. The method of claim 1 wherein the pre-mixed breaker fluid comprises 5 -35 wt % chelant.
7. The method of claim 1 wherein the aqueous fluid comprises a divalent brine.
8. The method of claim 1 further comprising circulating an alkyl glycoside.
9. A method of breaking a filtercake in a wellbore, the method comprising:
preparing a breaker fluid comprising:
a hydrolysable ester of carboxylic acid;
an alkyl glycoside; and
optionally, an amount of water, wherein
a weight ratio of water to hydrolysable ester of carboxylic acid is less than 1.3 to 1.
10. The method of claim 9 wherein the hydrolysable ester of carboxylic acid is a formic acid ester of a C2 to C30 alcohol.
11. The method of claim 9 , wherein the alkyl glycoside has the formula RO—(R′O) x Z y where the letter O represents an oxygen atom; R represents a monovalent alkyl radical containing from 8 to 16 carbon atoms; R′ represents a divalent alkyl radical containing 2 to 4 carbon atoms; x represents the number of oxy-alkylene units in the alkyl glycoside varying from 0 to about 12; Z represents a saccharide moiety containing 5 or 6 carbon atoms, and y represents the number of saccharide units in the glycoside.
12. The method of claim 11 , wherein y ranges from 1.3 to 1.8.
13. The method of claim 9 wherein the breaker fluid further comprises a blend of a base oil and at least one of a mutual solvent or a terpene; and the base oil comprises mineral oil or diesel.
14. The method of claim 13 , wherein the mutual solvent comprises at least one compound selected from the group consisting of ethylene glycol, ethylene glycol monobutyl ether, and butyl carbitol.
15. The method of claim 9 further comprising circulating an aqueous fluid to the wellbore.
16. The method of claim 15 wherein the aqueous fluid comprises a divalent brine.