# US 2014/0151042 A1 · Chelate Compositions And Methods And Fluids For Use In Oilfield Operations

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- Number: US 2014/0151042 A1
- Document ID: US20140151042A1
- Status: Published application
- Kind: A1
- Application number: 14/001,051
- Filed: 2012-02-22
- Published: 2014-06-05
- Earliest claimed: 2011-02-22
- Assignees: M-I L.L.C.
- Inventors: Lee Faugerstrom; Robert L. Horton; Mark Luyster; Chris Shepherd; Bethicia B. Prasek; James Lepage
- Web page: https://patentgrep.com/patent/US20140151042A1

## CPC

- C09K 8/582: characterised by the use of bacteria
- C09K 8/42: Compositions for cementing, e.g. for cementing casings into boreholes; Compositions for plugging, e.g. for killing wells (compositions for plastering C09K8/50)
- C09K 8/506: containing organic compounds
- C09K 8/52: Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
- C09K 8/62: Compositions for forming crevices or fractures
- E21B 33/138: Plastering the borehole wall; Injecting into the formation
- E21B 37/06: using chemical means for preventing or limiting {, e.g. eliminating,} the deposition of paraffins or like substances
- E21B 43/04: Gravelling of wells
- C09K 2208/24: Bacteria or enzyme containing gel breakers
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

A breaker fluid may include a base fluid; and an inactive chelating agent. A process may include pumping a first wellbore fluid comprising an inactive chelating agent into a wellbore through a subterranean formation; and activating the inactive chelating agent to release an active chelating agent into the wellbore.

## Claims

### Claim 1

A breaker fluid comprising:
a base fluid; and
an inactive chelating agent.

### Claim 2 (depends on 1)

The breaker fluid of claim 1, further comprising:
an enzyme source capable of activating the inactive chelating agent.

### Claim 3 (depends on 1)

The breaker fluid of claim 1, further comprising:
at least one of a surfactant, an oxidant, a pH buffer, a mutual solvent, a cleaning agent, and combinations thereof

### Claim 4 (depends on 2)

The breaker fluid of claim 2, wherein the enzyme source is added to the breaker fluid after both the base fluid and the inactive chelating agent have been introduced to a wellbore.

### Claim 5 (depends on 1)

The breaker fluid of claim 1, wherein the inactive chelating agent comprises at least one of an amido-chelant, an esterified-chelant, a nitrile-chelant, and combinations thereof.

### Claim 6 (depends on 5)

The breaker fluid of claim 5, wherein the amide, ester, nitrile, and anhydride linkage respectively present in the amido-chelant, esterified-chelant, and nitrile-chelant reduce the chelating strength of the inactive chelating agent.

### Claim 7 (depends on 5)

The breaker fluid of claim 5, wherein the amido-chelant comprises at least one of a polyethyl amide, an internal cyclic amide, and combinations thereof.

### Claim 8 (depends on 5)

The breaker fluid of claim 5, wherein the esterified-chelant comprises at least one of a polyethyl ester, an internal cyclic ester, and combinations thereof.

### Claim 9 (depends on 5)

The breaker fluid of claim 5, wherein the nitrile-chelant comprises a nitrile group.

### Claim 10 (depends on 2)

The breaker fluid of claim 2, wherein the enzyme source comprises at least one of an esterase, a phosphoric monoester hydrolase, a peptide hydrolase, a cysteine proteinase, a nitrilase, and combinations thereof.

### Claim 11 (depends on 10)

The breaker fluid of claim 10, wherein the cysteine proteinase comprises at least one of papain, fecin, bromelin, actinidin, and combinations thereof.

### Claim 12 (depends on 11)

The breaker fluid of claim 11, wherein the cysteine proteinase comprises papain.

### Claim 13

A process comprising:
pumping a first wellbore fluid comprising an inactive chelating agent into a wellbore through a subterranean formation; and
activating the inactive chelating agent to release an active chelating agent into the wellbore.

### Claim 14 (depends on 13)

The process of claim 13, further comprising:
pumping a second wellbore fluid comprising an enzyme source into the wellbore; and

### Claim 15 (depends on 14)

The process of claim 14, wherein the first wellbore fluid and the second wellbore fluid are pumped simultaneously as a single fluid.

### Claim 16 (depends on 14)

The process of claim 14, wherein the first wellbore fluid is pumped into the wellbore a predetermined amount of time before the second wellbore fluid is pumped into the wellbore.

### Claim 17 (depends on 13)

The process of claim 13, wherein the inactive chelating agent comprises at least one of an amido-chelant, an esterified-chelant, a nitrile-chelant, and combinations thereof.

### Claim 18 (depends on 13)

The process of claim 13, wherein the active chelating agent is capable of breaking or degrading a filter cake.

### Claim 19 (depends on 14)

The process of claim 14, wherein the first wellbore further comprises at least one polysaccharide polymer and bridging agent.

### Claim 20 (depends on 19)

The process of claim 19, further comprising:
allowing some filtration of the first wellbore fluid into the subterranean formation to produce a filter cake comprising the inactive chelating agent.

### Claim 21 (depends on 13)

The process of claim 13, wherein the first wellbore fluid further comprises:
at least one of a weighting agent, a wetting agent, a viscosifier, a fluid loss control agent, a surfactant, a dispersant, an interfacial tension reducer, a pH buffer, a mutual solvent, a thinner, a thinning agent, a cleaning agent, and combinations thereof.

### Claim 22 (depends on 20)

The process of claim 20, wherein the first wellbore fluid and the second wellbore fluid are pumped simultaneously as a single fluid into the wellbore.

### Claim 23 (depends on 20)

The process of claim 20, wherein the first wellbore fluid is pumped into the wellbore a predetermined amount of time before the second wellbore fluid is pumped into the wellbore.

### Claim 24 (depends on 13)

The process of claim 13, further comprising:
pumping a fluid loss pill comprising a crosslinked polymer, wherein the active chelating agent breaks at least a portion of the crosslinked polymer.

### Claim 25 (depends on 13)

The process of claim 13, further comprising:
pumping a fracturing fluid comprising a crosslinked polymer, wherein the active chelating agent breaks at least a portion of the crosslinked polymer.

### Claim 26

A process comprising:
pumping a first wellbore fluid comprising a polysaccharide polymer, a bridging agent, and an inactive chelating agent into a wellbore through a subterranean formation;
allowing some filtration of the first wellbore fluid into the subterranean formation to produce a filter cake comprising the polysaccharide polymer, bridging agent, and inactive chelating agent; and
activating the inactive chelating agent to release an active chelating agent wherein the released active chelating agent reacts with the bridging agent in the wellbore.

### Claim 27 (depends on 26)

The process of claim 26, further comprising:
pumping a second wellbore fluid comprising an enzyme source into the wellbore.

### Claim 28 (depends on 27)

The process of claim 27, wherein the enzyme source hydrolyzes at least a portion of the first wellbore fluid so as to activate the inactive chelating agent.

### Claim 29 (depends on 27)

The process of claim 27, wherein the first wellbore fluid is pumped into the wellbore a predetermined amount of time before the second wellbore fluid is pumped into the wellbore.