Patent ID: 8721873

Claim:
In a method for treating a crude oil to reduce its mercury level, comprising adding to the crude oil a water stream consisting essentially of an oxidizing agent to convert at least a portion of the mercury to mercury cations, and extracting at least a portion of the mercury cations into the water stream forming a mercury-rich wastewater, and separating the mercury-rich wastewater from the crude oil for a treated crude oil having a reduced concentration of mercury, the improvement consisting of: adding a complexing agent to convert at least a portion of the mercury cations to water soluble mercury compounds in a water phase prior to separating the water phase containing water soluble mercury compounds from the crude oil by water oil phase separation for a treated crude oil having a reduced mercury level; wherein the complexing agent is selected from the group of ethylenediamine, propylenediamine, triaminotriethylamine, diethylenetriamine, triethylenetetramine (TRIEN), tetra-2-aminoethylethlenediamine, tetraethylenepentamine (TETREN), ammonium thiosulfate, alkali metal thiosulfates, alkaline earth metal thiosulfates, iron thiosulfates, alkali metal dithionites, and alkaline earth metal dithionites, and mixtures thereof.