Process for the extraction of high molecular weight naphthenic acids from calcium naphthenate salts

Abstract

A method for recovering high molecular weight naphthenic tetra-acids, particularly ARN acids from a calcium naphthenate deposit. Calcium naphthenate deposits contain large amounts of calcium naphthenate salts of ARN acids. The method dual solvent extraction process in which the naphthenic tetra-acids chemically bound as calcium naphthenate salts are converted into free acid monomers by an aqueous acid. The resulting free acid monomers are then dissolved into an organic solvent phase and the counterions dissolve in the aqueous acid phase. The naphthenic tetra-acids are then recovered from the organic solvent phase.

1 . A naphthenic tetra-acid recovered from a dual solvent extraction of a calcium naphthenate deposit, the extraction process comprising:
 providing a calcium naphthenate deposit including a calcium naphthenate salt of a naphthenic tetra-acid and entrained crude oil;   providing an aqueous solvent solution including an aqueous acid and an organic solvent in a volumetric ratio effective to dissociate the naphthenic tetra-acid and calcium salt;   adding the calcium naphthenate deposit to the aqueous solvent solution in an effective mass ratio of solvent solution to deposit to form a multiphase mixture;   separating the multiphase mixture into a plurality of phases including an aqueous acid phase and an organic solvent phase;   recovering the naphthenic tetra-acid from the organic solvent phase.   
     
     
         2 . The tetra-acid of  claim 1 , wherein the naphthenic tetra-acid is an ARN acid. 
     
     
         3 . The tetra-acid of  claim 1 , wherein the naphthenic tetra-acid has a molecular weight ranging from about 1228 to about 1236 atomic mass units (amu).