Water treatment method for heavy oil production

A method of producing steam for downhole injection in the recovery of heavy oil, said method comprising:

• (a) providing an oil/water mixture gathered from an oil/water collection well,
• (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 to at least partially provide an evaporator feedwater, said evaporator feedwater comprising water, dissolved solutes, and dissolved gases, 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, and concentrating said evaporator feedwater to produce a concentrated heated brine, said evaporator having a plurality of heat transfer surfaces;
• (f) maintaining the pH of said concentrated heated brine as necessary to maintain solubility of silica therein at a selected concentration factor;
• (g) distributing said brine on a first surface of at least one of said plurality of heat transfer surfaces to generate a steam vapor;
• (h) discharging at least some of said brine as an evaporator blowdown stream;
• (i) slightly compressing said steam vapor to produce a compressed steam vapor;
• (j) directing said compressed steam vapor to a second surface of at least one of said plurality of heat transfer surfaces to condense said compressed steam vapor and to form a distillate;
• (k) collecting said distillate;
• (l) introducing said distillate into a boiler, to produce
• (i) steam,
• (ii) a boiler blowdown stream, said boiler blowdown stream comprising water and residual dissolved solids.
• (iii) adding said boiler blowdown stream to said evaporator feedwater prior to the step of heating said evaporator feedwater;
• (m) injecting said steam in injection wells to fluidize oil present in a selected geological formation, to produce an oil and water mixture for collection at a production well;
• (n) gathering said oil and water mixture.