Method for reducing acid in hydrocarbons

Abstract

A method, and use of, a surfactant is provided for reducing the total acid number (TAN) of produced hydrocarbons. The method may include introducing a surfactant to produced hydrocarbons, separating the surfactant from the produced hydrocarbons, and removing the surfactant and associated acid from the hydrocarbons. The cloud point of the surfactant may be used in the separating step of the method, and removal of the precipitate from the hydrocarbons may reduce the TAN of the hydrocarbons. The separation step may include forming an aqueous or intermediate phase that comprises the surfactant and associated acid.

What is claimed is: 
     
         1 . A method of reducing a total acid number (TAN) in produced hydrocarbons, the method comprising:
 introducing a surfactant to the produced hydrocarbons to solubilize, associate, complex, or encapsulate acid in the produced hydrocarbons;   separating the surfactant and solubilized, associated, complexed, or encapsulated acid from the produced hydrocarbons; and   removing the surfactant and solubilized, associated, complexed, or encapsulated acid.   
     
     
         2 . The method according to  claim 1 , wherein the surfactant solubilizes, associates, complexes, or encapsulates acid in the produced hydrocarbons at temperatures below a cloud point of the surfactant and while separating the surfactant and solubilized, associated, complexed, or encapsulated acid from the produced hydrocarbons, the temperature is increased above the cloud point to induce precipitation. 
     
     
         3 . The method according to  claim 1 , wherein the introduced surfactant is soluble in the produced hydrocarbons at temperatures below a cloud point of the surfactant. 
     
     
         4 . The method according to  claim 1 , wherein the surfactant hydrophilic-lipophilic balance (HLB) is about 1 to 8. 
     
     
         5 . The method according to  claim 2 , wherein the cloud point is manipulated by addition of salt. 
     
     
         6 . The method according to  claim 5 , wherein the salt is sodium chloride or ammonium sulfate. 
     
     
         7 . The method according to  claim 6 , wherein the sodium chloride is added to or above a concentration of between about 30,000 ppm and 80,000 ppm. 
     
     
         8 . The method according to  claim 1 , wherein the surfactant is precipitated by adjusting the temperature of the produced hydrocarbons to or above about 70° C. 
     
     
         9 . The method according to  claim 1 , wherein the surfactant and solubilized, associated, complexed, or encapsulated acid are formed in an aqueous phase or intermediate phase for subsequent removal. 
     
     
         10 . The method according to  claim 1 , wherein the surfactant and solubilized, associated, complexed, or encapsulated acid are formed in a microemulsion for subsequent removal. 
     
     
         11 . The method according to  claim 9 , wherein the HLD of the produced hydrocarbons following introducing the surfactant is adjusted to about 0 thereby forming the solubilized, associated, complexed, or encapsulated acid substantially in the intermediate phase. 
     
     
         12 . The method according to  claim 9 , wherein the HLD of the produced hydrocarbons following introducing a surfactant is adjusted to be negative thereby forming the solubilized, associated, complexed, or encapsulated acid substantially in the aqueous phase. 
     
     
         13 . The method according to  claim 1 , wherein the acid is a carboxylic acid. 
     
     
         14 . The method according to  claim 1 , wherein the surfactant is non-ionic. 
     
     
         15 . The method according to  claim 1 , wherein the surfactant is an ethoxylated or propxylated alcohol, an alkyl polyglycoside, or a combination thereof. 
     
     
         16 . The method according to  claims 1 , wherein the surfactant is a combination of two or more surfactants. 
     
     
         17 . The method according to  claim 1 , wherein the introduced surfactant is mixed with the produced hydrocarbons prior separating the surfactant and solubilized, associated, complexed, or encapsulated acid from the produced hydrocarbons. 
     
     
         18 . The method according to any one of  claims 1 , wherein mixing of the introduced surfactant and the produced hydrocarbons is performed during separation of the surfactant and solubilized, associated, complexed, or encapsulated acid from the produced hydrocarbons. 
     
     
         19 . A method of separating acid from produced hydrocarbons, the method comprising introducing a surfactant to the produced hydrocarbons to form an emulsion, microemulsion, intermediate phase, aqueous phase, or precipitate. 
     
     
         20 . A method of separating acid from produced hydrocarbons, the method comprising:
 introducing a surfactant to the produced hydrocarbons to solubilize, associate, complex, or encapsulate acid in the produced hydrocarbons; and   forming an intermediate or aqueous phase comprising the surfactant and solubilized, associated, complexed, or encapsulated acid.