Patent US4633949A successfully refreshed from Google Patents.
US4633949A
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Method of preventing precipitation of ferrous sulfide and sulfur during acidizing
Assignee: Schlumberger Technology Corp
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Filing: 1985-02-12
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Granted: 1987-01-06
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Expires: 2005-02-12
Abstract
Abstract An improved method of acidizing sour gas wells involving the injection of an aqueous acidizing solution comprising: water, an acid, an effective amount of an iron complexing agent (e.g., EDTA) capable of stabilizing the ferrous, Fe(II), ion in solution in the presence of H 2 S and an effective amount of an iron reducing agent (e.g., erythorbic acid, ascorbic acid and mixtures thereof) capable of reducing the ferric, Fe(III), ion in solution to ferrous Fe(II), ion at a pH of about 6.0 or less. Such a process is effective in reducing and inhibiting the precipitation of Fe(OH) 3 , FeS and S in sour wells.
Inventors
- 👤 Curtis W. Crowe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:22
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/52; C09K8/528; C09K8/532; C09K8/60; C09K8/62; C09K8/72; C09K8/74; Y; Y10; Y10S; Y10S166/00; Y10S166/902; Y10S507/00; Y10S507/933; Y10S507/934
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
127 words
A method of treating a subterranean earth formation penetrated by a wellbore comprising the steps of: (a) injecting down the wellbore and into contact with the formation an aqueous acidizing solution comprising: (i) water, (ii) an acid, (iii) an effective amount of an organic carboxylic acid iron complexing agent capable of stabilizing the ferrous, Fe(II), ion in solution in the presence of H 2 S, thus inhibiting the precipitation of FeS, and (iv) an effective amount of an iron reducing agent capable of reducing the ferric, Fe(III), ion at a pH of about 0.6 or less, thus inhibiting the formation of elemental sulfur; and (b) recovering from the formation the spent aqueous acidizing solution substantially free of having induced precipitation of FeS, S and Fe(OH) 3 .
Claim 2
Independent Claim
127 words
A method of treating a subterranean earth formation penetrated by a wellbore comprising the steps of: (a) injecting down the wellbore and into contact with the formation an aqueous acidizing solution comprising: (i) water, (ii) an acid, (iii) an effective amount of an organic carboxylic acid iron complexing agent capable of stabilizing the ferrous, Fe(II), ion in solution in the presence of H 2 S, thus inhibiting the precipitation of FeS, and (iv) an effective amount of an iron reducing agent capable of reducing the ferric, Fe(III), ion at a pH of about 0.6 or less, thus inhibiting the formation of elemental sulfur; and (b) recovering from the formation the spent aqueous acidizing solution substantially free of having induced precipitation of FeS, S and Fe(OH) 3 .
Claim 3
Dependent Claim
12 words
A method of claim 1 wherein the iron complexing agent is EDTA.
Claim 4
Dependent Claim
22 words
A method of claim 1 wherein the iron reducing agent is selected from the group consisting of erythorbic acid and ascorbic acid.
Claim 5
Dependent Claim
20 words
A method of claim 1 wherein the iron complexing agent is EDTA and the iron reducing agent is erythorbic acid.
Claim 6
Dependent Claim
13 words
A method of claim 1 wherein the iron complexing agent is nitrilotriacetic acid.
Claim 7
Dependent Claim
13 words
A method of claim 1 wherein the iron complexing agent is acetic acid.
Claim 8
Dependent Claim
13 words
A method of claim 1 wherein the iron complexing agent is citric acid.
Claim 9
Dependent Claim
13 words
A method of claim 1 wherein the iron complexing agent is lactic acid.
Claim 10
Dependent Claim
13 words
A method of claim 1 wherein the iron complexing agent is gluconic acid.
Claim 11
Dependent Claim
40 words
A method of claim 1 wherein the iron complexing agent is at least one of the acids selected from the group consisting of EDTA, nitrilotriacetic acid, acetic acid, citric acid, lactic acid, gluconic acid and salts or partial salts thereof.
Claim 12
Dependent Claim
22 words
A method of claim 10 wherein the iron reducing agent is selected from the group consisting of erythorbic acid and ascorbic acid.
Claim 13
Dependent Claim
13 words
A method of claim 11 wherein the iron reducing agent is erythorbic acid.
Claim 14
Independent Claim
109 words
A method of treating a subterranean earth formation penetrated by a wellbore comprising the steps of: (a) injecting down the wellbore and into contact with the formation an aqueous acidizing solution comprising: (i) water, (ii) an acid, (iii) an effective amount of an organic carboxylic acid iron complexing agent capable of stabilizing the ferrous, Fe(II), ion in solution in the presence of H 2 S, thus inhibiting the precipitation of FeS, and (iv) an effective amount of an iron reducing agent capable of reducing the ferric, Fe(III), ion at a pH of about 0.6 or less, thus inhibiting the formation of elemental sulfur; and (b) shutting in the wellbore.
Claim 15
Independent Claim
109 words
A method of treating a subterranean earth formation penetrated by a wellbore comprising the steps of: (a) injecting down the wellbore and into contact with the formation an aqueous acidizing solution comprising: (i) water, (ii) an acid, (iii) an effective amount of an organic carboxylic acid iron complexing agent capable of stabilizing the ferrous, Fe(II), ion in solution in the presence of H 2 S, thus inhibiting the precipitation of FeS, and (iv) an effective amount of an iron reducing agent capable of reducing the ferric, Fe(III), ion at a pH of about 0.6 or less, thus inhibiting the formation of elemental sulfur; and (b) shutting in the wellbore.
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