US4056146A
Expired / Lapsed
US
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Method for dissolving clay
Assignee: Halliburton Co
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Filing: 1976-07-06
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Granted: 1977-11-01
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Expires: 1996-07-06
Abstract
Abstract A method for dissolving clay is disclosed which comprises contacting the clay, in alteration, with separate slugs of a hydrogen ion-containing chemical and a fluoride ion-containing chemical. The hydrogen ions and fluoride ions react on the surface of the clay to produce hydrofluoric acid to dissolve the clay. The method is particularly valuable in dissolving the clay in a mixture of sand and clay without dissolving the sand. This finds immediate value in the practice of acid treating subterranean sandstone formations to increase permeability or to restore permeability damaged by clay.
Inventors
- 👤 Bobby E. Hall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:16
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/60; C09K8/62; C09K8/72
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
136 words
A method of dissolving clay comprising treating said clay with at least a one-stage treatment of at least two different chemicals, in alternate slugs, said one stage being comprised of contacting said clay with a slug of a first chemical and thereafter contacting said clay with a slug of a second chemical different from said first chemical to thereby form hydrofluoric acid on the surface of said clay, wherein said first chemical supplies one of hydrogen ions or fluoride ions and said second chemical supplies fluoride ions, if hydrogen ions are supplied by said first chemical, or hydrogen ions if fluoride ions are supplied by said first chemical wherein said chemical supplying said fluoride ions is an aqueous solution of a fluoride-containing chemical selected from the group consisting of ammonium bifluoride, ammonium fluoride, and mixtures thereof.
Claim 2
Independent Claim
136 words
A method of dissolving clay comprising treating said clay with at least a one-stage treatment of at least two different chemicals, in alternate slugs, said one stage being comprised of contacting said clay with a slug of a first chemical and thereafter contacting said clay with a slug of a second chemical different from said first chemical to thereby form hydrofluoric acid on the surface of said clay, wherein said first chemical supplies one of hydrogen ions or fluoride ions and said second chemical supplies fluoride ions, if hydrogen ions are supplied by said first chemical, or hydrogen ions if fluoride ions are supplied by said first chemical wherein said chemical supplying said fluoride ions is an aqueous solution of a fluoride-containing chemical selected from the group consisting of ammonium bifluoride, ammonium fluoride, and mixtures thereof.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein said fluoride chemical has a fluoride ion concentration in the range of from about 0.2N to about 5N.
Claim 4
Dependent Claim
25 words
The method of claim 2 wherein the pH of said fluoride chemical is adjusted with ammonium hydroxide to a value of at least about 7.
Claim 5
Dependent Claim
32 words
The method of claim 3 wherein said chemical supplying said hydrogen ions is an aqueous acidic solution having a hydrogen ion concentration in the range of from about 0.2N to about 5N.
Claim 6
Dependent Claim
19 words
The method of claim 4 wherein the hydrogen ion concentration is at least equal to the fluoride ion concentration.
Claim 7
Dependent Claim
22 words
The method of claim 5 wherein said aqueous acid solution is selected from hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid.
Claim 8
Dependent Claim
18 words
The method of claim 6 wherein said clay is a component in a mixture of sand and clay.
Claim 9
Dependent Claim
24 words
The method of claim 7 wherein said sand and clay mixture is treated with at least two and up to 10 of said stages.
Claim 10
Dependent Claim
13 words
The method of claim 8 wherein said sand-clay mixture is a sandstone formation.
Claim 11
Dependent Claim
46 words
The method of claim 9 wherein said sandstone formation is treated with a preflush material prior to treatment of said sandstone with any of said stages wherein said preflush material is selected from hydrochloric acid, ammonium chloride and a mixture of hydrochloric acid and hydrofluoric acid.
Claim 12
Dependent Claim
45 words
The method of claim 10 wherein said sandstone formation is treated with an afterflush material after treatment of said sandstone with all of said stages wherein said overflush material is selected from hydrochloric acid, ammonium chloride, and a mixture of hydrochloric acid and hydrofluoric acid.
Claim 13
Independent Claim
123 words
A method of acid treating a subterranean sandstone formation comprising contacting said formation with an aqueous hydrochloric acid solution containing about 5 percent hydrochloric acid by weight of solution, contacting said formation with an aqueous solution containing about 3 percent hydrofluoric acid and about 12 percent hydrochloric acid by weight of solution, contacting said formation with at least one stage of a clay dissolving system wherein said stage consists of an aqueous solution containing about 3 percent ammonium fluoride by weight of solution, followed by an aqueous solution containing about 5 percent hydrochloric acid by weight of solution and thereafter contacting said formation with a 5 percent by weight solution of hydrochloric acid or a 3 percent by weight solution of ammonium chloride.
Claim 14
Independent Claim
123 words
A method of acid treating a subterranean sandstone formation comprising contacting said formation with an aqueous hydrochloric acid solution containing about 5 percent hydrochloric acid by weight of solution, contacting said formation with an aqueous solution containing about 3 percent hydrofluoric acid and about 12 percent hydrochloric acid by weight of solution, contacting said formation with at least one stage of a clay dissolving system wherein said stage consists of an aqueous solution containing about 3 percent ammonium fluoride by weight of solution, followed by an aqueous solution containing about 5 percent hydrochloric acid by weight of solution and thereafter contacting said formation with a 5 percent by weight solution of hydrochloric acid or a 3 percent by weight solution of ammonium chloride.
Claim 15
Dependent Claim
25 words
The process of claim 12 wherein said sandstone formation is contacted with at least 2 and up to about 10 of said stages in succession.
Claim 16
Independent Claim
123 words
A method of acid treating a subterranean sandstone formation comprising contacting said formation with an aqueous hydrochloric acid solution containing about 5 percent hydrochloric acid by weight of solution; contacting said formation with at least one stage of a clay dissolving system wherein said stage consists of an aqueous solution containing about 3 percent ammonium fluoride by weight of solution, followed by an aqueous solution containing about 5 percent hydrochloric acid by weight of solution; contacting said formation with an aqueous solution containing about 3 percent hydrofluoric acid and about 12 percent hydrochloric acid by weight of solution; and thereafter contacting said formation with a 5 percent by weight solution of hydrochloric acid or a 3 percent by weight solution of ammonium chloride.
Claim 17
Independent Claim
123 words
A method of acid treating a subterranean sandstone formation comprising contacting said formation with an aqueous hydrochloric acid solution containing about 5 percent hydrochloric acid by weight of solution; contacting said formation with at least one stage of a clay dissolving system wherein said stage consists of an aqueous solution containing about 3 percent ammonium fluoride by weight of solution, followed by an aqueous solution containing about 5 percent hydrochloric acid by weight of solution; contacting said formation with an aqueous solution containing about 3 percent hydrofluoric acid and about 12 percent hydrochloric acid by weight of solution; and thereafter contacting said formation with a 5 percent by weight solution of hydrochloric acid or a 3 percent by weight solution of ammonium chloride.
Claim 18
Dependent Claim
25 words
The process of claim 14 wherein said sandstone formation is contacted with at least two and up to about 10 of said stages in succession.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-10-31 | 1981-05-02 | 1981-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-31 | 1985-05-02 | 1985-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-31 | 1989-05-02 | 1989-11-01 | $7700.00 | Window Closed / Lapsed |