Patent ID: 7591309

Claim:
A process for generating steam for downhole injection in a steam flood process for oil recovery, said process comprising: (a) heating a de-oiled produced water stream containing water, dissolved solutes, and dissolved gases, said dissolved solutes further comprising at least one molecular species which is at low ionization levels when in solution at around neutral pH, (b) raising the pH of said heated, produced water stream to maintain the solubility of said molecular species therein at a selected concentration factor, (c) pressurizing and directing said produced water stream to a circulating concentrated brine in a produced water evaporator, said evaporator having a plurality of heat transfer surfaces, (d) distributing said circulating brine across a first surface of at least one of said plurality of heat transfer surfaces to generate a steam vapor suitable for injection into a selected geological formation to fluidize oil, (e) discharging at least some of said brine as an evaporator blowdown stream, (f) distributing steam from a watertube boiler across a second surface of at least one of said plurality of heat transfer surfaces to condense said steam as a condensate, (g) returning said condensate to said watertube boiler for steam production, and, (h) discharging at least some of said condensate as a boiler blowdown to the produced water evaporator.