Wettability alteration with smart water in carbonates: Effect of calcium,magnesium and sulfate multivalent ions, salinity, optimum concentration of sulfate

Increasing evidence has shown that the adjusting of ionic composition of water injection in the reservoir can improve oil recovery. The carbonate reservoirs comprise about the %05 of oil reservoirs and most of them are neutral to oil wet. More than %%5 of carbonate reservoirs are oil wet and 125 are intermediate wet. Wettability is a very important factor in the oil recovery mechanisms. Because it has drastic effect on the distribution and flowing of the oil and water in the reservoirs. Ionic composition adjusting of water which is referred as smart water is known as one of wettability alteration methods in the carbonate reservoirs. Although the mechanisms behind of this technic don’t have recognized enough but wettability alteration is a result of these mechanisms. The effect of individual ions must be investigate for better recognition of mechanisms causing improving oil recovery. For complete investigation of mechanisms of smart water technic it must be studied about the crude oil/formation water/injection water/rock system but this system is very complex and for better understanding it must become simpler. In this study, the aim is the wettability alteration with smart water. The investigation of sulfate, calcium and magnesium ions effect on the wettability alteration and the comparison of sulfate performance with these ions on the catalytically effect on wettability alteration is studied. Also the effect of low salinity, optimum salinity of sulfate in smart water and dynamic tests are done.

Keywords:

smart water , sulfate , calcium , magnesium , carbonate reservoir , wettability