US3768561A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for controlling unconsolidated sand in an oil well with permeable cement
Assignee: Texaco Inc
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Filing: 1971-12-20
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Granted: 1973-10-30
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Expires: 1991-12-20
Abstract
Abstract The movement of unconsolidated sand from a subterranean hydrocarbon-containing formation into a wellbore during recovery of the formation hydrocarbon fluids is prevented by forming a permeable, acid-susceptible cement barrier between the formation and the wellbore. The permeability of said acid-susceptible cement barrier or pack traversing a producing formation is improved by treatment with a composition comprised of mineral acid having dissolved therein a vinylpyrrolidone polymer, which composition slowly reacts with acid-soluble components accumulated at the pack face and within the cement pack so that the permeability of the cement barrier to the flow of formation hydrocarbon fluids is increased while adequate mechanical strength and proper pore size to prevent the movement of unconsolidated formation sand into the bore-hole is maintained and recovering formation hydrocarbon fluids from the formation through the formed permeable cement barrier.
Inventors
- 👤 J Tate
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:44
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/56; C09K8/57; C09K8/575; C09K8/5751; C09K8/60; C09K8/62; C09K8/72; C09K8/74; C09K8/78; C09K8/84; C09K8/845; C09K8/86; C09K8/88
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
28 words
A method as described in claim 1 wherein the said acid component of the treating composition is selected from the group consisting of hydrochloric acid and sulfuric acid.
Claim 2
Dependent Claim
25 words
The method of claim 1 wherein the acidic solution has a concentration of from about 3 to about 30 percent by weight of the acid.
Claim 3
Dependent Claim
15 words
The method of claim 1 wherein the vinylpyrrolidone polymer comprises recurring units of the formula:
Claim 4
Dependent Claim
20 words
The method of claim 1 wherein the vinylpyrrolidone polymer has a molecular weight of from about 10,000 to about 1,000,000.
Claim 5
Dependent Claim
20 words
The method of claim 1 wherein the vinylpyrrolidone polymer has a molecular weight of from about 10,000 to about 400,000.
Claim 6
Dependent Claim
11 words
The method of claim 1 wherein the vinylpyrrolidone polymer is polyvinylpyrrolidone.
Claim 7
Dependent Claim
36 words
The method of claim 1 wherein the said vinylpyrrolidone polymer is present in a concentration of from about 0.1 to about 10 percent by weight based on the total solution weight of the vinylpyrrolidone polymer-acid solution.
Claim 8
Dependent Claim
73 words
The method of claim 1 wherein the treating composition is maintained in contact with the cement barrier for a time sufficient for the acid to react chemically with the acid-soluble components of the cement barrier and to etch passageways therethrough thereby increasing substantially the formation fluid flow capacity of the said cement barrier while still maintaining the effectiveness of the said cement barrier for restraining the flow of unconsolidated sand into the wellbore.
Claim 9
Dependent Claim
33 words
The method of claim 1 further comprising the step of removing the treating composition and its reaction products by reducing injection pressure and permitting said treating composition to flow back into the well.
Claim 10
Dependent Claim
24 words
The method of claim 1 further comprising the Step of washing the cement barrier with salt water prior to injecting the acid-vinylpyrrolidone polymer solution.
Claim 11
Independent Claim
39 words
A method for increasing the permeability of a permeable cement barrier in a wellbore penetrating an incompetent subterranean hydrocarbon-containing formation which comprises injecting into said cement barrier an aqueous solution of mineral acid having dissolved therein a vinylpyrrolidone polymer.
Claim 12
Dependent Claim
20 words
The method of claim 12 wherein said acid is selected from the group consisting of hydrochloric acid and sulfuric acid.
Claim 13
Dependent Claim
11 words
The method of claim 12, wherein said acid is hydrochloric acid.
Claim 14
Dependent Claim
11 words
The method of claim 12 wherein said acid is sulfuric acid.
Claim 15
Dependent Claim
25 words
The method of claim 12 wherein the acid solution has a concentration of from about 3 to about 30 percent by weight of the acid.
Claim 16
Dependent Claim
15 words
The method of claim 12 wherein the vinylpyrrolidone polymer comprises recurring units of the formula:
Claim 17
Dependent Claim
20 words
The method of claim 12 wherein the vinylpyrrolidone polymer has a molecular weight of from about 10,000 to about 1,000,000.
Claim 18
Dependent Claim
20 words
The method of claim 12 wherein the vinylpyrrolidone polymer has a molecular weight of from about 10,000 to about 400,000.
Claim 19
Dependent Claim
11 words
The method of claim 12 wherein the vinylpyrrolidone polymer is polyvinylpyrrolidone.
Claim 20
Dependent Claim
35 words
The method of claim 12 wherein the vinylpyrrolidone polymer is present in a concentration of from about 0.1 to about 10 percent by weight based on the total solution weight of the vinylpyrrolidone polymer-acid solution.
Claim 21
Dependent Claim
72 words
The method of claim 12 wherein the treating composition is maintained in contact with the cement barrier for a time sufficient for the acid to react chemically with the acid-soluble components of the cement barrier to etch passageways therethrough thereby increasing substantially the formation fluid flow capacity of the said cement barrier while still maintaining the effectiveness of the said cement barrier for restraining the flow of unconsolidated sand into the wellbore.
Claim 22
Dependent Claim
33 words
The method of claim 12 further comprising the step of removing the treating composition and its reaction products by reducing injection pressure and permitting said treating composition to flow back into the well.
Claim 23
Dependent Claim
27 words
The method of claim 12 further comprising the step of washing the face of the permeable cement barrier with salt water before injecting the acid-vinylpyrrolidone polymer solution.
Claim 24
Dependent Claim
35 words
The method of claim 12 further comprising the step of washing the cement barrier with salt water after the treating composition has reacted with the cement barrier to remove the residual acid-polymer and reaction products.
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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) | 1976-10-29 | 1977-04-30 | 1977-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-29 | 1981-04-30 | 1981-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-29 | 1985-04-30 | 1985-10-30 | $7700.00 | Window Closed / Lapsed |