Patent ID: 8685233

Claim:
A method of removal of calcium from a hydrocarbon feedstock consisting essentially of the steps of: (a) mixing a hydrocarbon stream including crude oil containing metals and salts thereof, wherein the metals and salts thereof include calcium and/or calcium naphthenate, characterized in that the hydrocarbon stream is mixed with an effective metal removing amount of an aqueous extraction solution of an additive comprising a chemical compound selected from a group consisting of maleic acid, maleic anhydride, fumaric acid, salts of maleic acid, salts of maleic anhydride, salts of fumaric acid, derivatives of maleic acid, derivatives of maleic anhydride, derivatives of fumaric acid, and combinations thereof, enabling formation of a hydrocarboneous phase and an aqueous phase containing metal ions; (b) permitting formation of said aqueous phase and said hydrocarboneous phase, wherein said aqueous phase includes an ionic water soluble metal acid complex of a calcium salt of said additive; (c) separating or permitting to separate by themselves said two phases in a crude desalter, or by using any of conventional processes of separation; (d) removing the separated aqueous phase of step (c), wherein the separated aqueous phase contains said metal acid complex; and (e) processing the separated hydrocarboneous phase of step (c) by downstream hydrocarbon processing techniques; wherein, the contact time between said aqueous extraction solution of said additive and said hydrocarbon stream during the mixing action of step (a) is in the range from two seconds to six hours; wherein the temperature in said crude desalter is in the range from 93Â° C. to 163Â° C.; and wherein the weight percentage of the dosage of said chemical compound ranges from 0.001 to 5 weight percent of desalter wash water.