Patent ID: 7455109

Claim:
A method of recovering hydrocarbons from a porous subterranean hydrocarbon-bearing formation comprising the steps of: (a) feeding a first stream comprising a high salinity water to a first side of a semipermeable membrane of at least one forward osmosis unit of a desalination plant and feeding a second stream comprising an aqueous solution of a removable solute to a second side of the semipermeable membrane wherein the solute concentration of the aqueous solution of the removable solute is sufficiently greater than the solute concentration of the high salinity water that water passes through the semipermeable membrane from the high salinity water into the aqueous solution of the removable solute to form a diluted aqueous solution of the removable solute; (b) withdrawing a third stream comprising a concentrated brine and a fourth stream comprising a diluted aqueous solution of the removable solute from the first and second sides respectively of the semipermeable membrane of the forward osmosis unit; (c) substantially separating the removable solute from the fourth stream comprising the diluted aqueous solution of the removable solute to form a low salinity water stream having a total dissolved solids content of less than 5000 ppm; (d) if necessary, increasing the salinity of the low salinity water stream to a total dissolved solids content of at least 200 ppm, preferably, at least 500 ppm; (e) introducing the treated low salinity water into the hydrocarbon-bearing formation via an injection well; (f) displacing the hydrocarbons with the treated low salinity water towards an associated production well; and (g) recovering hydrocarbons from the formation via the production well.