US3841405A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Subsurface formation treatment
Assignee: BP America Production Co
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Filing: 1973-05-22
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Granted: 1974-10-15
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Expires: 1993-05-22
Abstract
Abstract This concerns the plugging of a highly permeable underground zone penetrated by a well and/or the consolidation of loosely consolidated sand. Formaldehyde is injected through the well into the zone. Thereafter, H2S is injected. When the H2S contacts the formaldehyde, a polymer gel is formed in-place in the zone. Relatively high concentrations of formaldehyde and H2S result in essentially complete plugging of the formation so that it loses essentially all of its permeability. Use of smaller quantities of formaldehyde and hydrogen sulfide results in consolidating loose sand formation, yet permits the sand to retain some permeability so that fluids can flow therethrough.
Inventors
- 👤 T Moote
- 👤 R Vandaveer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 11:45
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/50; C09K8/502; C09K8/56; C09K8/57; C09K8/575; C09K8/5751; C09K8/5755
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
49 words
A METHOD OF TREATING A HIGHLY PERMEABLE UNDERGROUND ZONE PENETRATED BY A WELL WHICH COMPRISES INJECTING FORMALDEHYDE THROUGH SAID WELL INTO SAID ZONE; INJECTING H2S INTO SAID ZONE THROUGH SAID WELL WHEREBY A GEL IS FORMED IN-PLACE IN THE ZONE FROM THE REACTION OF THE H2S CONTACTING THE FORMALDEHYDE.
Claim 2
Independent Claim
49 words
A METHOD OF TREATING A HIGHLY PERMEABLE UNDERGROUND ZONE PENETRATED BY A WELL WHICH COMPRISES INJECTING FORMALDEHYDE THROUGH SAID WELL INTO SAID ZONE; INJECTING H2S INTO SAID ZONE THROUGH SAID WELL WHEREBY A GEL IS FORMED IN-PLACE IN THE ZONE FROM THE REACTION OF THE H2S CONTACTING THE FORMALDEHYDE.
Claim 3
Dependent Claim
25 words
A method as defined in claim 1 by which the formaldehyde is injected As at least about 35 percent by weight in a formaldehyde-water solution.
Claim 4
Dependent Claim
19 words
A method as defined in claim 1 in which, prior to injection, the said H2S is mixed with nitrogen.
Claim 5
Dependent Claim
18 words
A method as defined in claim 1 which includes a step of adding a stabilizer to the formaldehyde.
Claim 6
Dependent Claim
38 words
A method as defined in claim 1 in which a hot fluid is injected into said well to melt at least a part of said gel, and then at least a part of the melted gel is removed.
Claim 7
Dependent Claim
49 words
A method as defined in claim 1 in which, at a time after the formation of polymer gel, a 10-percent solution of acetone by weight in water is injected through said well into said zone to dissolve at least a part of the polymer gel to increase the permeability.
Claim 8
Dependent Claim
36 words
A method as defined in claim 1 in which the amount of H2S injected is limited such that sufficient polymer gel is formed to consolidate sand particles of said zone, but insufficient to form complete plugging.
Claim 9
Dependent Claim
37 words
A method as defined in claim 2 in which, after the formation of said gel, a solvent is injected through said well into said zone, said solvent selected from the following group: chloroform, dichloroethane, dichloropropane, and toluene.
Claim 10
Independent Claim
63 words
A method of consolidating an unconsolidated underground zone penetrated by a well which comprises: injecting a formaldehyde water solution, in which the formaldehyde is not over about 5 percent by weight of the solution, through said well into said zone; injecting H2S into said zone whereby a polymer gel is formed in situ cementing particles of said zone into a consolidated permeable mass.
Claim 11
Independent Claim
63 words
A method of consolidating an unconsolidated underground zone penetrated by a well which comprises: injecting a formaldehyde water solution, in which the formaldehyde is not over about 5 percent by weight of the solution, through said well into said zone; injecting H2S into said zone whereby a polymer gel is formed in situ cementing particles of said zone into a consolidated permeable mass.
Claim 12
Dependent Claim
21 words
A method as defined in claim 9 including the step of introducing nitrogen into said H2S to decrease its partial pressure.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |