Subsurface injection of reject stream

1. A method for recovering oil from a subterranean formation, comprising:

processing a source water to produce a processed water stream and a reject water stream;

injecting a first fluid into an injection well toward a first downhole exhaust, wherein the first fluid comprises the processed water stream; and

injecting a second fluid into the injection well toward a second downhole exhaust, wherein the second fluid comprises the reject water stream, wherein the first fluid is separated from the second fluid within the injection well and wherein the first fluid and the second fluid each are injected into a formation layer; and

producing oil from the formation via a production well.

2. The method of claim 1 , further comprising injecting a third fluid into the injection well toward a third outlet point, wherein the third fluid is separated from the first fluid and second fluid within the injection well.

3. The method of claim 1 , wherein the first fluid comprises an oil recovery fluid.

4. The method of claim 1 , wherein the first fluid comprises an enhanced oil recovery fluid.

5. The method of claim 1 , wherein the first fluid and the second fluid are injected into the same formation layer.

6. The method of claim 1 , wherein the first fluid is injected into a first formation layer and the second fluid is injected into a second formation layer.

7. The method of claim 6 , wherein the second formation layer is below the first formation layer.

8. The method of claim 1 , wherein the source water comprises a seawater, aquifer, fresh water, brine, ocean water, surface water, river water, pond water, produced water, treated produced water, or municipal water.

9. The method of claim 1 , wherein processing the source water produces substantially equal amounts of the processed water stream and the reject water stream.

10. A system for recovering oil from a subterranean formation, comprising:

an injection well extending into at least one formation layer;

a spacer disposed within the injection well and separating a first injection zone disposed within the injection well and a second injection zone disposed within the injection well;

a first conduit disposed within the injection well and a second conduit disposed within the injection well, wherein the first conduit comprises a first fluid exhaust in fluid communication with the first injection zone and wherein the second conduit comprises a second fluid exhaust in fluid communication with the second injection zone;

a filtration device structured and arranged to direct a processed water toward the first conduit and direct a reject water toward the second conduit; and

a production well in fluid communication with the at least one formation layer.

11. The system of claim 10 , further comprising a produced water conduit structured and arranged to direct produced water toward the first conduit or the second conduit.

12. The system of claim 10 , further comprising a third conduit disposed within the injection well comprising a third fluid exhaust in fluid communication with a third injection zone, wherein the third injection zone is downhole of the second injection zone.

13. The system of claim 12 , further comprising a second spacer disposed within the injection well separating the second injection zone from a third injection zone.

14. The system of claim 10 , wherein the second injection zone is downhole from the first injection zone.