Patent ID: 7150320

Claim:
A process for producing steam for downhole injection in the recovery of heavy oii, said process comprising: (a) providing an oil/water mixture gathered from oil/water collection wells; (b) substantially separating oil from said oil/water mixture to provide an oil product and an oil containing produced water; (c) de-oiling said oil containing produced water residue to at least partially provide an evaporator feedwater, said evaporator feedwater comprising water, dissolved gases, and dissolved solutes, said dissolved solutes comprising silica; (d) heating said evaporator feedwater to remove at least some of said dissolved gases; (e) injecting said evaporator feedwater into an evaporator, said evaporator having a plurality of heat transfer elements; (f) distributing said brine on a first surface of at least one of said plurality of heat transfer elements, concentrating said evaporator feedwater, and generating a steam vapor; (g) discharging at least some of said brine as an evaporator blowdown stream; (h) slightly compressing said steam vapor to produce a compressed steam vapor; (i) directing said compressed steam vapor to a second surface of at least one of said plurality of heat transfer elements to condense said compressed steam vapor and to form a distillate stream, said distillate stream having a volume of at least ninety five percent or more of said evaporator feedwater stream; (j) collecting said distillate stream; (k) introducing said distillate stream into a boiler, to produce (i) steam, (ii) a boiler blowdown stream which is five percent or less by volume of said treated water stream, said boiler blowdown stream comprising water and residual dissolved solids; (l) injecting said steam in an injection well to fluidize oil present in a selected geological formation, to produce an oil and water mixture; (m) gathering said oil/water mixture from a production well.