Method for removing calcium from crude oil

Abstract

Methods for reducing calcium deposition along surfaces in contact with the water phase of a resolved water/oil emulsion are disclosed. High calcium crude oil and the like are contacted with a sequestrant to form a sequestered calcium containing complex that partitions to the water phase in the resolved emulsion. A specifically formulated polymeric deposit control agent is added to the water phase to inhibit calcium deposit formation therein and along surfaces in contact with the water phase.

1 . Method for reducing calcium content in a liquid hydrocarbonaceous medium comprising: 
 a. contacting said liquid hydrocarbonaceous medium with a metal sequestering agent to form a sequestered calcium containing complex;    b. contacting said liquid hydrocarbonaceous medium with an aqueous medium to form an emulsion whereby upon resolution of said emulsion at least a portion of said sequestered calcium containing complex remains in said aqueous medium; and    c. contacting said aqueous medium with a water soluble or water dispersible polymer having the formula I to inhibit calcium deposit formation therein or along surfaces in contact with said aqueous medium, wherein said polymer has the formula:                          wherein E is the repeat unit remaining after polymerization of an ethylenically unsaturated compound; R 1  is H or lower (C 1 -C 6 ) alkyl; G is lower (C 1 -C 6 ) alkyl or carbonyl; Q is O or NH; R 2  is lower (C 1 -C 6 ) alkyl; hydroxy lower (C 1 -C 6 ) alkyl, lower (C 1 -C 6 ) alkyl sulfonic acid -(Et-O)— n  —-(iPr-O)— n  or —(Pr—O—) n  wherein n ranges from about 1 to 100 alkyl, and R 3  is H or XZ wherein X is an anionic radical selected from the group consisting of SO 3 , PO 3  or COO; Z is H or hydrogens or any other water soluble cationic moiety which counterbalances the valence of the anionic radical X; F, when present, is a repeat unit having the Formula II:                          wherein X and Z are the same as in Formula I; R 4  is H or (C 1 -C 6 ) lower alkyl, R 5  is a hydroxy substituted alkyl or alkylene having from 1 to 6 atoms, and XZ may or may not be present; c and d are positive integers, e is a non-negative integer, and j is 0 or 1.    
   
   
       2 . Method as recited in  claim 1  wherein from about 1 to 300 ppm of said polymer (I) is brought into contact with said aqueous medium, based on one million parts of said aqueous medium.  
   
   
       3 . Method a recited in  claim 2  wherein from about 1 to 100 ppm of said polymer (I) is brought into contact with said aqueous medium.  
   
   
       4 . Method as recited in  claim 3  wherein said liquid hydrocarbonaceous medium has a calcium content of greater than about 30 ppm calcium based upon one million parts of said liquid hydrocarbonaceous medium.  
   
   
       5 . Method as recited in  claim 4  wherein said liquid hydrocarbonaceous medium is crude oil.  
   
   
       6 . Method as recited in  claim 5  wherein said metal sequestering agent is citric acid or salt thereof and wherein said sequestered calcium containing complex is calcium citrate.  
   
   
       7 . Method as recited in  claim 6  wherein said polymer I is a member or members selected from the group consisting of 
 1) AA/AHPSE;    2) AA/APES;    3) AA/AMPS;    4) AA/APES/AHPSE    5) AA/MA/APES    6) AA/AMPS/APES    
   
   
       8 . Method as recited in  claim 7  wherein said polymer I is 
 1) AA/AHPSE;    2) AA/APES; or    3) AA/AMPS    
   
   
       9 . Method as recited in  claim 8  wherein said polymer I is AA/AHPSE.  
   
   
       10 . Method as recited in  claim 8  wherein said polymer I is AA/APES.  
   
   
       11 . Method as recited in  claim 8  wherein said polymer I is AA/AMPS.  
   
   
       12 . Method as recited in  claim 8  further comprising contacting said emulsion with an emulsion breaker.  
   
   
       13 . Method as recited in  claim 12  further comprising adding a corrosion inhibitor to said liquid hydrocarbonaceous medium or to said aqueous medium.  
   
   
       14 . Method as recited in  claim 8  wherein said emulsion is heated to a temperature of about 100° F.-300° F.  
   
   
       15 . Method as recited in  claim 14  wherein said resolution of said emulsion is performed in a desalter apparatus.  
   
   
       16 . Method as recited in  claim 15  wherein n in Formula I is from 1 to 20 and X in Formula I is selected from Na, K, Ca, and NH 4 .  
   
   
       17 . A method for reducing calcium deposition along surfaces in contact with a water phase formed as a result of resolution of an emulsion in a petroleum refinery desalter of the type wherein crude oil containing calcium therein is contacted with a sequestrant and a water wash to form said emulsion having a sequestered calcium complex in said emulsion, wherein at least a portion of said sequestered calcium complex partitions to said water phase upon said resolution, said method comprising contacting said sequestered calcium complex with a water soluble or water dispersible polymer having the Formula I:  
     
       
         
         
             
             
         
       
     
     wherein E is the repeat unit remaining after polymerization of an ethylenically unsaturated compound; R 1  is H or lower (C 1 -C 6 ) alkyl; G is lower (C 1 -C 6 ) alkyl or carbonyl; Q is O or NH; R 2  is lower (C 1 -C 6 ) alkyl; hydroxy lower (C 1 -C 6 ) alkyl, lower (C 1 -C 6 ) alkyl sulfonic acid; -(Et-O)— n  —(iPr-O)— n  or —(Pr—O—) n  wherein n ranges from about 1 to 100, and R 3  is H or XZ wherein X is an anionic radical selected from the group consisting of SO 3 , PO 3  or COO; Z is H or hydrogens or any other water soluble cationic moiety which counterbalances the valence of the anionic radical X; F, when present, is a repeat unit having the Formula II:  
     
       
         
         
             
             
         
       
     
     wherein X and Z are the same as in Formula I. R 4  is H or (C 1 -C 6 ) lower alkyl, R 5  is a hydroxy substituted alkyl or alkylene having from 1 to 6 atoms, and XZ may or may not be present; c and d are positive integers, e is a non-negative integer, and j is 0 or 1.  
   
   
       18 . Method as recited in  claim 17  wherein said crude oil comprises about 100 ppm calcium and greater.  
   
   
       19 . Method is recited in  claim 18  wherein said sequestrant is citric acid and wherein said sequestered calcium complex is calcium citrate, and wherein about 1 to 300 ppm of said polymer I is added to said water phase based on one million parts of said water phase, said polymer comprising a member or members selected from the group consisting of 
 1) AA/AHPSE    2) AA/APES    3) AA/AMPS    4) AA/APES/AHPSE    5) AA/MA/APES    6) AA/AMPS/APES    
   
   
       20 . Method as recited in  claim 19  wherein said polymer I is 
 1) AA/AHPSE;    2) AA/APES; or    3) AA/AMPS.    
   
   
       21 . Method as recited in  claim 1  wherein said liquid hydrocarbonaceous medium is crude oil produced at an oil production site and wherein said steps (a) through (c) are performed proximate said site.