Removal of sulfate from seawater

Patent metadata

Field	Value
Publication number	US-12448307-B2
Application number	US-202217659076-A
Country	US
Kind code	B2
Filing date	Apr 13, 2022
Priority date	Apr 13, 2022
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

A method and system of providing seawater into a subterranean formation, including adding chloride salt having a metal cation to the seawater (having sulfate), precipitating sulfate salt (of the metal cation and sulfate), removing the sulfate salt as precipitated to give treated seawater having less sulfate than the seawater, and injecting the treated seawater into the subterranean formation.

First claim

What is claimed is:

1. A method of providing seawater into a subterranean formation, comprising:
adding chloride salt to the seawater to give a mixture, wherein the seawater comprises sulfate, wherein adding the chloride salt comprises:
adding a first chloride salt comprising a first metal cation during a first batch time;
adding a second chloride salt comprising a second metal cation during a second batch time that is distinct from and after the first batch time;
wherein the second metal cation is different than the first metal cation;

precipitating sulfate salt in the mixture in a batch process having a total batch time that includes the first batch time and the second batch time, the sulfate salt comprising the first metal cation, the second metal cation, and sulfate, and wherein the sulfate salt is precipitated during the first batch time and the second batch time of the batch process before removing the sulfate salt as precipitated from the mixture;
removing the sulfate salt as precipitated from the mixture to give treated seawater comprising less sulfate than the seawater; and
injecting the treated seawater into the subterranean formation.

2. The method of claim 1 , wherein the first metal cation comprises barium, calcium, or strontium, or any combinations thereof, and wherein injecting comprises injecting the treated seawater through a wellbore of a well into an oil reservoir in the subterranean formation, thereby facilitating pressure maintenance of the oil reservoir.

3. The method of claim 1 , wherein the sulfate salt comprises barium sulfate, calcium sulfate, or strontium sulfate, or any combinations thereof, and wherein injecting comprises injecting the treated seawater through a wellbore of a well into an oil reservoir in the subterranean formation, thereby displacing crude oil in the oil reservoir through the subterranean formation toward a production well.

4. The method of claim 1 , wherein injecting comprises injecting the treated seawater through a wellbore of a water well into an aquifer in the subterranean formation, thereby facilitating a squeeze treatment of the water well with a scale inhibitor.

5. The method of claim 4 , comprising:
producing aquifer water from the aquifer through the wellbore of the water well to a surface conduit, wherein the aquifer water as produced comprises the scale inhibitor;
flowing the aquifer water as produced through the surface conduit to an injection well; and
injecting the aquifer water discharged from the surface conduit into an oil reservoir in a subterranean formation via the injection well, thereby facilitating pressure maintenance of the oil reservoir or thereby displacing crude oil in the oil reservoir toward a production well, or a combination thereof.

6. The method of claim 1 , wherein the first metal cation comprises calcium (Ca 2+ ) or strontium (Sr 2+ ), or both, and wherein the second metal cation comprises barium (Ba 2+ ).

7. The method of claim 1 , comprising:
specifying a maximum concentration of sulfate in the treated seawater; and
selecting the chloride salt for adding to the seawater in response to the maximum concentration.

8. The method of claim 7 , wherein the seawater comprises at least 3000 milligrams per liter (mg/L) of sulfate, wherein the first metal cation comprises barium chloride, calcium chloride, or strontium chloride, or any combinations thereof, and wherein the maximum concentration of sulfate specified for the treated seawater is in a range of 15 mg/L to 1000 mg/L.

9. The method of claim 1 , comprising specifying an amount of the chloride salt added in response to a maximum concentration of sulfate specified for the treated seawater, wherein adding the chloride salt comprises adding the amount of the salt as specified to the seawater, wherein the first metal cation comprises barium (Ba 2+ ), calcium (Ca 2+ ), or strontium (Sr 2+ ), or any combinations thereof, and wherein the seawater comprises at least 2000 milligrams per liter (mg/L) of sulfate.

10. The method of claim 1 , wherein the first chloride salt comprises calcium chloride or strontium chloride, or both, and wherein the second chloride salt comprises barium chloride.

11. A method of providing seawater into a subterranean formation, comprising:
adding salt to seawater having sulfate comprising sulfate anions, thereby precipitating a sulfate compound, wherein adding the salt comprises:
adding a first chloride salt comprising a first metal cation during a first batch time;
adding a second chloride salt comprising a second metal cation during a second batch time that is distinct from and after the first batch time;
wherein the second metal cation is different than the first metal cation;
wherein adding the salt occurs in a batch process having a total batch time that includes the first batch time and the second batch time; and

separating the sulfate compound as precipitated from the seawater to give treated seawater having a lower concentration of sulfate than the seawater, and wherein the sulfate compound is precipitated during the first batch time and the second batch time of the batch process before separating the sulfate salt from the seawater;
specifying a maximum concentration of sulfate in the treated seawater; and
injecting the treated seawater into a subterranean formation.

12. The method of claim 11 , wherein the first metal cation comprises barium (Ba 2+ ), calcium (Ca 2+ ), or strontium (Sr 2+ ), or any combinations thereof, wherein the sulfate compound comprises barium sulfate, calcium sulfate, or strontium sulfate, or any combinations thereof, and wherein injecting comprises injecting the treated seawater through a wellbore of a well into the subterranean formation for enhanced oil recovery (EOR).

13. The method of claim 11 , wherein the first metal cation comprises calcium (Ca 2+ ) or strontium (Sr 2+ ), or both, and wherein the second metal cation comprises barium (Ba 2+ ), wherein the seawater comprises at least 2000 milligrams per liter (mg/L) of sulfate, wherein injecting comprises injecting the treated seawater through a wellbore of a well into an oil reservoir in the subterranean formation, thereby facilitating pressure maintenance of the oil reservoir or thereby displacing crude oil in the oil reservoir through the subterranean formation toward a production well, or a combination thereof.

14. The method of claim 11 , comprising specifying the salt added to the seawater in response to the maximum concentration as specified, thereby maintaining concentration of sulfate in the treated seawater below the maximum concentration as specified.

15. The method of claim 11 , comprising adjusting an amount of the salt added in response to the maximum concentration as specified.

16. The method of claim 11 , wherein the first metal cation comprises calcium (Ca 2+ ) or strontium (Sr 2+ ), or both, and wherein the second metal cation comprises barium (Ba 2+ ).

17. The method of claim 11 , comprising adjusting an amount of time for the sulfate compound to precipitate in response to the maximum concentration of sulfate as specified, thereby maintaining concentration of sulfate in the treated seawater below the maximum concentration as specified.

18. A method of providing seawater into a subterranean formation, comprising:
adding salt to seawater having sulfate, thereby precipitating a sulfate salt, wherein adding the salt comprises:
adding a first chloride salt comprising a first metal cation during a first batch time;
adding a second chloride salt comprising a second metal cation during a s

Assignees

• Saudi Arabian Oil Co

Inventors

• Wang Qiwei
• Chen Tao
• Al-Jeshi Yasser A
• Alghamdi Nada

Classifications

• C02F2101/101

  Sulfur compounds · CPC title

• C02F2303/22

  Eliminating or preventing deposits, scale removal, scale prevention (C02F1/042, C02F1/4602, C02F5/00 take precedence) · CPC title

• C02F2305/00

  Use of specific compounds during water treatment · CPC title

• C02F2103/08

  Seawater, e.g. for desalination · CPC title

• C02F2209/19

  SO4-S · CPC title