Water treatment method for heavy oil production using calcium sulfate seed slurry evaporation

Abstract From the Canadian patent

A process for treating produced water to generate high pressure steam. Produced water from heavy oil recovery operations is treated by first removing oil and grease. Feedwater is then acidified and steam stripped to remove alkalinity and dissolved non-condensable gases. Pretreated produced water is then fed to an evaporator. Up to 95% or more of the pretreated produced water stream is evaporated to produce (1) a distillate having a trace amount of residual solutes therein and (2) evaporator blowdown containing substantially all solutes from the produced water feed. The distillate may be directly used or polished to remove the trace residual solutes before being fed to a steam generator. …