Patent ID: 8616283

Claim:
A process for treating a water stream produced in the recovery of heavy oil from geological formations comprising: a) injecting steam or warm water underground into a geological formation containing hydrocarbons and establishing a steam chamber; b) transferring heat from said steam chamber to said formation and mobilizing hydrocarbons for extraction from said formation; c) extracting said mobilized hydrocarbons from said formation and said hydrocarbons forming an emulsion with a portion of condensed water formed from said steam; d) separating mobilized hydrocarbons as a heavy oil product from said hydrocarbon-water emulsion to produce a water stream containing foulants that include residual hydrocarbons and solids; e) passing said water stream through a heat exchange unit comprising at least one tube wherein said tube has a multi-layer coating comprising a melt flowable copolymer of tetrafluoroethylene adhered to the interior surface or exterior surface of said tube, wherein said multi-layer coating is adhered to the interior surface or exterior surface of said tube by applying a primer layer to the surface of said tube; disposing an overcoat on top of said primer layer, wherein said overcoat comprises multiple layers including a lower layer and an upper layer and wherein said upper layer has an exterior anti-stick surface consisting essentially of baked perfluoropolymer; and f) removing said foulants from said water stream while altering the temperature of said water stream as said water stream passes through said heat exchange unit; wherein said multi-layer coating provides an anti-stick surface that reduces the deposition of foulants, on the interior or exterior surface of said tube as compared to the surface of said tube without said multi-layer coating being present, so as to avoid loss of efficiency in heat transfer and pluggage of said heat exchange unit.