Alternating microsphere and smartwater injection for enhanced oil recovery
A method for enhanced oil recovery in a reservoir is provided. The method includes injecting a microsphere suspension, including polymeric microspheres dispersed in seawater, into an injection well in the reservoir and injecting a low salinity tailored water (SmartWater) into the injection well in the reservoir. Oil is produced from a production well in the reservoir.
1. A method for enhanced oil recovery in a reservoir, comprising:
injecting a microsphere suspension, comprising polymeric microspheres dispersed in seawater, into an injection well in the reservoir, wherein the polymeric microspheres are between about 10 nm and about 100 nm;
injecting SmartWater into the injection well in the reservoir to swell the polymeric microspheres diverting flow of the SmartWater into unswept regions of the reservoir;
injecting saltwater into the injection well to shrink the polymeric microspheres and move the polymeric microspheres in the reservoir;
injecting a second slug of Smartwater into the injection well to swell the polymeric microspheres and diverting flow into another unswept region in the reservoir; and
producing oil from a production well in the reservoir.
2. The method of claim 1 , comprising injecting seawater into the injection well after the SmartWater.
3. The method of claim 1 , wherein a microsphere is a polyacrylamide-based preformed gel in an oil emulsion.
4. The method of claim 3 , wherein a particle size of the microsphere is between about 10 nm to about 10 μm before swelling.
5. The method of claim 1 , comprising mixing an emulsion of the polymeric microspheres with the seawater.
6. The method of claim 5 , wherein a concentration of the polymeric microspheres in the seawater is between 0.1 wt. % and 0.5 wt. %.
7. The method of claim 5 , wherein a concentration of the polymeric microspheres in the seawater is between 0.1 wt. % and 0.3 wt. %.
8. The method of claim 5 , wherein the seawater has a total dissolved solids of between about 35,000 ppm to about 56,700 ppm.
9. The method of claim 1 , wherein the reservoir comprises a carbonate reservoir.
10. The method of claim 9 , wherein the carbonate reservoir is a permeable matrix type carbonate reservoir.
11. The method of claim 1 , wherein a total dissolved solids (TDS) of the SmartWater is between about 4,000 ppm to about 8,000 ppm.
12. The method of claim 1 , wherein the SmartWater comprises sulfate ions at a concentration of between about 300 ppm to about 1000 ppm.
13. The method of claim 1 , wherein the SmartWater comprises divalent ions at a concentration of less than about 300 ppm.
14. The method of claim 1 , wherein the microsphere suspension is injected at a volume of between about 0.05 pore volume (PV) and about 1 PV of the reservoir.
15. The method of claim 1 , wherein the SmartWater is injected at a volume of between about 0.1 pore volume (PV) and about 1 PV of the reservoir.