Emulsion neutralization of high total acid number (TAN) crude oil

Abstract

This invention is a method for reducing the total acid number of organic acid containing petroleum oil comprising forming a water-in-oil emulsion comprising an aqueous Group IIA metal hydroxide solution or slurry in a hydrocarbon oil, said water-in-oil emulsion having an aqueous droplet particle size diameter of from 1 to 25μ, adding the water-in-oil emulsion to the organic acid containing petroleum oil and permitting the mixture to stand for a time sufficient to permit the neutralization of the organic acids in the petroleum oil.

1 . A process for reducing the acidity of an acid containing crude comprising: 
 (a) securing an aqueous alkaline earth metal hydroxide solution or slurry;    (b) forming a water-in-oil emulsion of the aqueous alkaline earth metal hydroxide solution or slurry in a hydrocarbon carrier oil, the water-in-oil emulsion having an aqueous phase droplet size of between about 0.5 to 50μ;    (c) mixing the water-in-oil emulsion with the acid containing crude to be treated in an amount such that the alkaline earth metal hydroxide content of the amount of emulsion added ranges from substoichiometric to in excess of the stoichiometric amount of metal needed to neutralize the total acid content of the quantity of crude or fraction thereof to be treated.    (d) holding the mixture at a temperature and for a time sufficient to effect the desired level of neutralization of the crude or fraction thereof to be treated; and    (e) passing the treated crude or fraction thereof on for further processing.    
   
   
       2 . The process of  claim 1  wherein the water-in-oil emulsion has an aqueous phase droplet size of between about 1 to 25μ.  
   
   
       3 . The process of  claim 1  wherein the water-in-oil emulsion has an aqueous phase droplet size of between about 1 to 10μ.  
   
   
       4 . The process of  claim 1 ,  2  or  3  wherein the mixture of water-in-oil emulsion and crude or fraction thereof to be treated is held at a temperature between about 20° C. to 150° C.  
   
   
       5 . The process of  claim 1 ,  2  or  3  wherein the mixture of water-in-oil emulsion and crude or fraction thereof to be treated is held at a temperature between about 20° C. to 100° C.  
   
   
       6 . The process of  claim 1 ,  2  or  3  wherein the mixture of water-in-oil emulsion and crude or fraction thereof to be treated is held at a temperature between about 20° C. to 60° C.  
   
   
       7 . The process of  claim 1 ,  2  or  3  wherein the mixture of water-in-oil emulsion and crude or fraction thereof to be treated is held for at least 2 hours.  
   
   
       8 . The process of  claim 1 ,  2  or  3  wherein the aqueous alkaline earth metal hydroxide solution or slurry is prepared by mixing a fine powder of alkaline earth metal hydroxide into water, the fine powder having a particle size in the range of the subsequent average aqueous droplet size in the water-in-oil emulsion.  
   
   
       9 . The proviso of  claim 1 ,  2  or  3  wherein the alkaline earth metal hydroxide is calcium hydroxide.  
   
   
       10 . The process of  claim 1 ,  2  or  3  wherein the water-in-oil emulsion comprises about 5 to 45 vol % of aqueous alkaline earth metal hydroxide solution or slurry to hydrocarbon carrier oil.  
   
   
       11 . The process of  claim 1 ,  2  or  3  wherein the mixing of the water-in-oil emulsion and the crude or fraction thereof to be treated is in a tank.  
   
   
       12 . The process of  claim 11  wherein the tank is in a tanker.  
   
   
       13 . The process of  claim 11  wherein the tank is a crude storage tank.  
   
   
       14 . The process of  claim 1 ,  2  or  3  wherein the mixing of the water-in-oil emulsion and the crude or fraction thereof to be treated is in a crude transport pipeline.  
   
   
       15 . The process of  claim 1 ,  2  or  3  wherein the amount of water-in-oil emulsion added to the crude or fraction thereof to be treated is such that the alkaline earth metal hydroxide content is about 0.375 to 0.5 mole of metal per mole of acid to be neutralized.  
   
   
       16 . The process of  claim 1 ,  2  or  3  wherein the treated crude or fraction thereof is dewatered and desalted.  
   
   
       17 . The process of  claim 1 ,  2  or  3  wherein the water-in-oil emulsion and the crude or fraction thereof to be treated is mixed at a ratio of about 0.2 to 10 volumes of emulsion to 100 volumes of crude or fraction thereof to be treated.