US4030548A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Economically dissolving barium sulfate scale with a chelating agent
Assignee: Shell USA Inc
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Filing: 1976-04-28
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Granted: 1977-06-21
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Expires: 1996-04-28
Abstract
Abstract A barium sulfate scale or solid can be dissolved economically by flowing a stream of relatively dilute aqueous solution of aminopolyacetic acid salt chelating agent into contact with and along the surfaces of the scale while correlating the composition and flow rate of the solution so that each portion of solution contains an amount of chelant effective for dissolving barium sulfate and the upstream portions of the scale are contacted by portions of the solution which are unsaturated regarding the barium-chelant complex.
Inventors
- 👤 Edwin A. Richardson
- 👤 Ronald F. Scheuerman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:26
CPC Classifications
C; C02; C02F; C02F5/00; C02F5/08; C09; C09K; C09K8/00; C09K8/52; C09K8/528; C23; C23G; C23G1/00; C23G1/24; Y; Y10; Y10S; Y10S507/00; Y10S507/927
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
132 words
A process for dissolving barium sulfate solid from a remote location into which fluid can be flowed comprising: flowing fluid into the remote location so that a stream of fluid contacts and flows along the surfaces of the barium sulfate solid, and adjusting the composition and flow rate of the fluid so that (a) the barium sulfate solid is contacted by a stream of aqueous solution in which each portion contains enough dissolved aminopolyacetic acid salt chelating agent to be effective in dissolving barium sulfate scale, (b) substantially all upstream portions of the barium sulfate solid are contacted by succeeding portions of the aqueous solution that are substantially unsaturated with respect to the dissolved barium-chelant complex, and (c) said aqueous solution contains from about 0.02-0.05 moles per liter of the chelating agent.
Claim 2
Dependent Claim
132 words
A process for dissolving barium sulfate solid from a remote location into which fluid can be flowed comprising: flowing fluid into the remote location so that a stream of fluid contacts and flows along the surfaces of the barium sulfate solid, and adjusting the composition and flow rate of the fluid so that (a) the barium sulfate solid is contacted by a stream of aqueous solution in which each portion contains enough dissolved aminopolyacetic acid salt chelating agent to be effective in dissolving barium sulfate scale, (b) substantially all upstream portions of the barium sulfate solid are contacted by succeeding portions of the aqueous solution that are substantially unsaturated with respect to the dissolved barium-chelant complex, and (c) said aqueous solution contains from about 0.02-0.05 moles per liter of the chelating agent.
Claim 3
Dependent Claim
16 words
The process of claim 1 in which the chelating agent is an ethylenediamine tetraacetic acid salt.
Claim 4
Dependent Claim
23 words
The process of claim 2 in which the chelant-containing solution contains at least about 3% by weight of dissolved inorganic alkali metal salt.
Claim 5
Dependent Claim
29 words
The process of claim 2 in which the remote location is a permeable subterranean earth formation containing particles of barium sulfate solid deposited by a barium sulfate-containing drilling mud.
Claim 6
Dependent Claim
19 words
The process of claim 1 in which the pH of the aqueous solution is from about 6 to 14.
References Cited (Backward Citations)
US2777818A
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US3660287A
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US3523582A
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US3684720A
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US3688829A
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US3793209A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-06-20 | 1980-12-20 | 1981-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-20 | 1984-12-20 | 1985-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-20 | 1988-12-20 | 1989-06-21 | $7700.00 | Window Closed / Lapsed |