US4051901A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for water treatment in mobility controlled caustic flooding process
Assignee: Union Oil Company of California
•
Filing: 1976-10-12
•
Granted: 1977-10-04
•
Expires: 1996-10-12
Abstract
Abstract A process for recovering petroleum from subterranean reservoirs where high salt content water is used in a secondary recovery process consisting of forming as the displacement fluid a dilute alkaline silicate solution utilizing the high salt content water and filtering the alkaline flooding solution to remove scale-forming alkali insoluble salts which include a substantial proportion of calcium and magnesium salts. The filtered solution is injected into the reservoir and this is followed by an injection of a slug of substantially neutral water. A dilute acid solution is utilized to contact and dissolve the alkaline insoluble salts which have been filtered from the alkaline solution and the thus formed solution which includes a substantial portion of soluble calcium and magnesium salts is injected into the reservoir for subsequent contact with the alkaline silicate solution. This contact results in the formation of precipitates which partially plug that portion of the reservoir in which the contact occurs and reduces the permeability thereof. The process is repeated a plurality of times until the desired amount of alkaline silicate solution has been injected into the reservoir whereupon untreated water can be injected as a drive fluid.
Inventors
- 👤 Amir M. Sarem
- 👤 Russell C. Darr
- 👤 Dale L. Elchlepp
- 👤 Robert B. Spratt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:39
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/54; C02; C02F; C02F5/00; C02F5/02; C09K8/58; E; E21; E21B; E21B41/00; E21B41/02; E21B43/00; E21B43/16; E21B43/20; Y; Y10; Y10S; Y10S166/00; Y10S166/902
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
213 words
A process for recovering petroleum from a subterranean reservoir penetrated by an injection well and a production well spaced apart in the reservoir which comprises alternately injecting into the reservoir through the injection well for a selected time period a petroleum displacement fluid comprising a dilute alkaline aqueous solution of an alkali metal silicate and thereafter injecting for a selected time period a dilute aqueous precipitate-forming solution of a material that reacts with the alkali metal silicate to form a precipitate, said alkali metal silicate solution further containing alkaline insoluble, scale forming salts comprising cations which form insoluble silicates, the improvement comprising: a. separating said alkaline insoluble salts from said dilute aqueous alkali metal silicate solution prior to the injection of said solution into the reservoir thereby to reduce the scaling tendency of said alkaline alkali metal silicate solution; b. contacting said alkaline insoluble salts with a dilute aqueous acid solution to dissolve said salts and to form a precipitate-forming solution comprising said cations which form insoluble silicates; and c. injecting into said reservoir said solution of step b subsequent to the injection of said alkaline alkali metal silicate solution where by contact between the solutions results in the formation of precipitate and the reduction of reservoir permeability in the area of contact.
Claim 2
Dependent Claim
213 words
A process for recovering petroleum from a subterranean reservoir penetrated by an injection well and a production well spaced apart in the reservoir which comprises alternately injecting into the reservoir through the injection well for a selected time period a petroleum displacement fluid comprising a dilute alkaline aqueous solution of an alkali metal silicate and thereafter injecting for a selected time period a dilute aqueous precipitate-forming solution of a material that reacts with the alkali metal silicate to form a precipitate, said alkali metal silicate solution further containing alkaline insoluble, scale forming salts comprising cations which form insoluble silicates, the improvement comprising: a. separating said alkaline insoluble salts from said dilute aqueous alkali metal silicate solution prior to the injection of said solution into the reservoir thereby to reduce the scaling tendency of said alkaline alkali metal silicate solution; b. contacting said alkaline insoluble salts with a dilute aqueous acid solution to dissolve said salts and to form a precipitate-forming solution comprising said cations which form insoluble silicates; and c. injecting into said reservoir said solution of step b subsequent to the injection of said alkaline alkali metal silicate solution where by contact between the solutions results in the formation of precipitate and the reduction of reservoir permeability in the area of contact.
Claim 3
Dependent Claim
28 words
The process of claim 1 wherein substantially neutral water is injected into the reservoir as a spacer between injection of said petroleum displacement fluid and said precipitate-forming solution.
Claim 4
Dependent Claim
21 words
The process of claim 1 wherein said alkaline insoluble salts are separated from said aqueous alkali metal silicate solution by filtration.
Claim 5
Dependent Claim
18 words
The process of claim 1 wherein said alkaline insoluble salts comprise the salts of the alkaline earth metals.
Claim 6
Dependent Claim
56 words
The process of claim 1 wherein said dilute aqueous alkaline alkali metal silicate solution comprises between about 0.01 wt.% and about 0.8 wt.% of alkali metal silicate and is prepared by diluting a more concentrated aqueous alkali metal silicate solution with water and subsequently passing said dilute solution through a filter to remove alkaline insoluble salts.
Claim 7
Dependent Claim
25 words
The process of claim 5 wherein the water used to form the dilute alkaline alkali metal silicate solution contains alkaline insoluble calcium and magnesium salts.
Claim 8
Dependent Claim
26 words
The process of claim 1 wherein said dilute aqueous acid solution comprises at least the stoichiometric amount of acid to solubilize the separated alkaline insoluble salts.
Claim 9
Dependent Claim
22 words
The process of claim 1 wherein said dilute acid solution comprises an acid which forms water soluble salts with calcium and magnesium.
Claim 10
Dependent Claim
51 words
The process of claim 1 wherein said alkaline alkali metal silicate solution is injected into the reservoir over a period ranging from between about 1 hour and about 7 days said precipitate-forming solution is injected into the reservoir over a period ranging from between about 1 hour and about 7 days.
Claim 11
Dependent Claim
31 words
The process of claim 9 wherein a spacer of substantially neutral water is injected into the reservoir between the injection of said alkaline alkali metal silicate solution and said precipitate-forming solution.
Claim 12
Dependent Claim
214 words
A process for recovering petroleum from a subterranean reservoir penetrated by one or more injection wells and one or more production wells spaced apart from said injection well, said process comprising the steps of: a. mixing an alkaline alkali metal silicate solution with water containing calcium and magnesium alkaline insoluble salts to form a dilute aqueous alkali metal silicate solution having a pH of between about 9 and about 13 and an alkali metal oxide/silica ratio of at least about 1; b. passing said dilute aqueous alkali metal silicate solution through a filter to remove and recover the alkaline insoluble calcium and magnesium salts which have precipitated from said solution; c. injecting said filtered alkali metal silicate solution into said reservoir through at least one of said injection wells for a pre-selected period of time; d. thereafter injecting substantially neutral water for a pre-selected period of time; e. dissolving said alkaline insoluble calcium and magnesium salts with a dilute acid solution thereby to form an aqueous solution comprising calcium and magnesium; f. injecting said solution comprising calcium and magnesium into said reservoir for a pre-selected period of time; g. injecting neutral water for a selected period of time; h. repeating steps a-g a plurality of times; and i. recovering fluids from said production well.
Claim 13
Dependent Claim
214 words
A process for recovering petroleum from a subterranean reservoir penetrated by one or more injection wells and one or more production wells spaced apart from said injection well, said process comprising the steps of: a. mixing an alkaline alkali metal silicate solution with water containing calcium and magnesium alkaline insoluble salts to form a dilute aqueous alkali metal silicate solution having a pH of between about 9 and about 13 and an alkali metal oxide/silica ratio of at least about 1; b. passing said dilute aqueous alkali metal silicate solution through a filter to remove and recover the alkaline insoluble calcium and magnesium salts which have precipitated from said solution; c. injecting said filtered alkali metal silicate solution into said reservoir through at least one of said injection wells for a pre-selected period of time; d. thereafter injecting substantially neutral water for a pre-selected period of time; e. dissolving said alkaline insoluble calcium and magnesium salts with a dilute acid solution thereby to form an aqueous solution comprising calcium and magnesium; f. injecting said solution comprising calcium and magnesium into said reservoir for a pre-selected period of time; g. injecting neutral water for a selected period of time; h. repeating steps a-g a plurality of times; and i. recovering fluids from said production well.
Claim 14
Dependent Claim
25 words
The process of claim 11 wherein said dilute alkali metal silicate solution comprises between about 0.01 and about 0.8 wt.% of said alkali metal silicate.
Claim 15
Dependent Claim
13 words
The process of claim 11 wherein said alkali metal silicate is sodium silicate.
Claim 16
Dependent Claim
23 words
The process of claim 11 wherein said dilute aqueous alkali metal silicate solution has a pH of between about 10 and about 12.
Claim 17
Dependent Claim
17 words
The process of claim 14 wherein said alkali metal silicate solution has a pH of about 12.
Claim 18
Dependent Claim
22 words
The process of claim 11 wherein said dilute aqueous alkali metal silicate solution has an alkali metal oxide/silica molar ratio of 2.
Claim 19
Dependent Claim
30 words
The process of claim 11 wherein the acid concentration of said dilute aqueous acid solution is at least the stoichiometric amount of acid required to dissolve said alkaline insoluble salts.
Claim 20
Dependent Claim
37 words
The process of claim 11 wherein said preselected period of time for injecting said filtered dilute aqueous silicate solution and said solution comprising calcium and magnesium salts ranges from between about 1 hour to about 7 days.
Claim 21
Dependent Claim
64 words
The process of claim 11 wherein said filtered dilute alkaline alkali metal silicate solution is first injected into the reservoir for 15 hours followed by the injection of substantially neutral water for a period of 1 hour, then said solution comprising calcium and magnesium is injected into said reservoir for a period of 7 hours followed by a 1-hour injection of substantially neutral water.
Claim 22
Dependent Claim
27 words
The process of claim 11 wherein steps a-g are repeated until about 0.2 pore volumes of alkaline alkali metal silicate solution has been injected into said reservoir.
References Cited (Backward Citations)
US2261100A
Cited
US2903065A
Cited
US3136359A
Cited
US3515215A
Cited
US3530937A
Cited
US3658131A
Cited
US3805893A
Cited
US3871452A
Cited
US3926255A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-10-03 | 1981-04-04 | 1981-10-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-03 | 1985-04-04 | 1985-10-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-03 | 1989-04-04 | 1989-10-04 | $7700.00 | Window Closed / Lapsed |