# US 8,770,296 B2 · High density breaker fluids and methods of use thereof

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- Number: US 8,770,296 B2
- Document ID: US8770296B2
- Status: Granted
- Kind: B2
- Application number: 12/991,064
- Filed: 2009-05-04
- Published: 2011-03-17
- Granted: 2014-07-08
- Earliest claimed: 2008-05-05
- Assignees: M-I L.L.C.
- Applicants: Raul Navarro-mascarell; Mark Luyster
- Inventors: Raul Navarro-mascarell; Mark Luyster
- Web page: https://patentgrep.com/patent/US8770296B2

## CPC

- C09K 8/524: organic depositions, e.g. paraffins or asphaltenes
- C09K 2208/24: Bacteria or enzyme containing gel breakers
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

A wellbore fluid that includes an aqueous base fluid; a chelating agent; and at least one enzyme, wherein the wellbore fluid has a pH of at least 6.5 is disclosed.

## Claims

### Claim 1

A wellbore fluid, comprising:
an aqueous base fluid;
a chelating agent, wherein the chelating agent comprises K3EDTA; and
at least one enzyme,
wherein the wellbore fluid has a pH of at least 7.5.

### Claim 2 (depends on 1)

The wellbore fluid of claim 1, wherein the wellbore fluid has a density of greater than 9.5 ppg.

### Claim 3 (depends on 2)

The wellbore fluid of claim 2, wherein the wellbore fluid has a density of greater than 10 ppg.

### Claim 4 (depends on 1)

The wellbore fluid of claim 1, wherein the wellbore fluid has a pH of at least 8.

### Claim 5 (depends on 1)

The wellbore fluid of claim 1, further comprising:
at least one mutual solvent.

### Claim 6 (depends on 1)

The wellbore fluid of claim 1, further comprising:
at least one surfactant.

### Claim 7 (depends on 1)

The wellbore fluid of claim 1, wherein the aqueous base fluid comprises monovalent salts therein.

### Claim 8

A method of cleaning a wellbore drilled with a wellbore fluid that forms a filter cake, the method comprising:
emplacing a breaker fluid into the wellbore, the breaker fluid comprising:
an aqueous fluid;
a chelating agent, wherein the chelating agent comprises K3EDTA; and
at least one enzyme, wherein the wellbore fluid has a pH of at least 7.5; and
shutting in the well for a period of time sufficient to initiate breaking of the filter cake.

### Claim 9 (depends on 8)

The method of claim 8, further comprising:
collecting the breaker fluid having at least a portion of the broken filter cake therein.

### Claim 10 (depends on 8)

The method of claim 8, further comprising:
circulating a wash fluid through the wellbore.

### Claim 11 (depends on 8)

The method of claim 8, further comprising:
initiating production of formation fluids through the wellbore.

### Claim 12 (depends on 8)

The method of claim 8, further comprising:
performing at least one completion operation in the wellbore.

### Claim 13 (depends on 8)

The method of claim 8, wherein the breaker fluid has a density of greater than 9.5 ppg.

### Claim 14 (depends on 13)

The method of claim 13, wherein the breaker fluid has a density of greater than 10 ppg.

### Claim 15 (depends on 8)

The method of claim 8, wherein the breaker fluid has a pH of at least 8.

### Claim 16 (depends on 8)

The method of claim 8, wherein the aqueous base fluid comprises monovalent salts therein.

### Claim 17

A wellbore fluid, comprising:
an aqueous base fluid;
a chelating agent, wherein the chelating agent is K3EDTA; and
at least one enzyme,
wherein the wellbore fluid has a pH of at least 6.5.