# US 11,441,396 B1 · Sand consolidation for subterranean sand formations

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- Number: US 11,441,396 B1
- Document ID: US11441396B1
- Status: Granted
- Kind: B1
- Application number: 17/724,052
- Filed: 2022-04-19
- Granted: 2022-09-13
- Earliest claimed: 2021-11-05
- Assignees: King Fahd University of Petroleum and Minerals
- Applicants: King Fahd University of Petroleum and Minerals
- Inventors: Sidqi Ahmad M Abu-Khamsin; Mohamed Ahmed Nasr Eldin Mahmoud; Saad Fahaid Khalaf Al-Afnan; Murtada Saleh Hassan Al-Jawad; Ahmed Hamdy Gowida
- Web page: https://patentgrep.com/patent/US11441396B1

## CPC

- E21B 43/025: {Consolidation of loose sand or the like round the wells without excessively decreasing the permeability thereof}
- C09K 8/565: Oil-based compositions
- C09K 8/592: Compositions used in combination with generated heat, e.g. by steam injection
- C09K 8/594: Compositions used in combination with injected gas {, e.g. CO2 orcarbonated gas}(C09K8/592 takes precedence)
- E21B 36/008: {using chemical heat generating means}
- E21B 43/166: {Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium (CO2 injection E21B43/164; steam injection E21B43/24)}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

A method of sand consolidation is provided. The method includes injecting a consolidating fluid into a subterranean sand formation via a wellbore to saturate a portion of the subterranean sand formation in a target region surrounding the wellbore and displace a formation fluid present in the subterranean sand formation. Herein, the consolidating fluid comprises bitumen dissolved in an aromatic solvent. The method further includes injecting a composition comprising one or more heat-generating chemicals into the subterranean sand formation such that the portion of the subterranean sand formation in the target region is heated to a target temperature of at least 150° C. The method further includes injecting a gas comprising oxygen into the subterranean sand formation for a period sufficient to oxidize the bitumen in the target region into a residue present on sand grains to bind the sand grains together into a consolidated permeable matrix. A volume fraction of the residue in the consolidated permeable matrix in the target region is about 5-30%.

## Claims

### Claim 1

A method of sand consolidation, the method comprising:
injecting a consolidating fluid into a subterranean sand formation via a wellbore to saturate a portion of the subterranean sand formation in a target region surrounding the wellbore and displace a formation fluid present in the subterranean sand formation, wherein the consolidating fluid comprises bitumen dissolved in an aromatic solvent;
injecting a composition comprising one or more heat-generating chemicals into the subterranean sand formation such that the portion of the subterranean sand formation in the target region is heated to a target temperature of from 150° C. to 220° C., the one or more heat-generating chemicals diluting the consolidating fluid in the target region; and
injecting a gas comprising oxygen into the subterranean sand formation for a period sufficient to oxidize the bitumen in the target region into a residue present on sand grains of the subterranean sand formation to bind the sand grains together into a consolidated permeable matrix,
wherein a volume fraction of the residue in the consolidated permeable matrix in the target region is about 5-30%, and
wherein the injecting the composition comprises injecting ammonium and nitrite.

### Claim 2 (depends on 1)

The method of claim 1, further comprising injecting an acidic activator comprising acetic acid to activate an exothermal reaction between the ammonium and the nitrite.

### Claim 3 (depends on 2)

The method of claim 2, wherein:
the ammonium and the nitrite are injected into the subterranean sand formation to form a mixture therein, and
the acidic activator is injected into the mixture.

### Claim 4 (depends on 3)

The method of claim 3, wherein:
the ammonium and the nitrite are injected into the subterranean sand formation in batches to form batches of mixtures, and
the acidic activator is injected into each batch of mixtures.

### Claim 5 (depends on 2)

The method of claim 2, wherein the ammonium and the nitrite are injected separately into the subterranean sand formation.

### Claim 6 (depends on 5)

The method of claim 5, wherein the acidic activator is pre-mixed with one of the ammonium and the nitrite before injecting into the subterranean sand formation.

### Claim 7 (depends on 2)

The method of claim 2, wherein the acidic activator has a concentration of 7-13% by volume of a total volume of the ammonium and the nitrite.

### Claim 8 (depends on 1)

The method of claim 1, wherein:
the ammonium comprises ammonium chloride, and
the nitrite comprises sodium nitrite.

### Claim 9 (depends on 8)

The method of claim 8, wherein:
the ammonium comprises 2-4 mol/L ammonium chloride, and
the nitrite comprises 2-4 mol/L sodium nitrite.

### Claim 10 (depends on 1)

The method of claim 1, wherein permeability of the subterranean sand formation is reduced by less than 20% after injecting the consolidating fluid, the composition and the gas in comparison to the permeability of the subterranean sand formation before injecting the consolidating fluid, the composition and the gas.

### Claim 11 (depends on 1)

The method of claim 1, wherein the aromatic solvent comprises toluene or xylene.

### Claim 12 (depends on 1)

The method of claim 1, wherein the target region extends radially from the wellbore to the subterranean sand formation by up to 4 feet.

### Claim 13 (depends on 1)

The method of claim 1, wherein the period for injecting the gas is about 6-10 hours.

### Claim 14 (depends on 1)

The method of claim 1, wherein the injecting the composition comprises injecting 6-8 bbl of the heat-generating chemicals per each foot of a thickness of the subterranean sand formation.

### Claim 15 (depends on 1)

The method of claim 1, prior to the injecting the consolidating fluid into the subterranean sand formation, the method further comprising:
flushing the target region with a mutual solvent to at least partially remove the formation fluid from the target region.

### Claim 16 (depends on 1)

The method of claim 1, wherein the formation fluid comprises water, crude oil, gas or a combination thereof.

### Claim 17 (depends on 1)

The method of claim 1, wherein the subterranean sand formation comprises carbonate minerals.