Method for destabilizing bitumen-water and oil-water emulsions using lime

Abstract

In a process for destabilizing bitumen-water emulsions to facilitate bitumen recovery therefrom, bitumen-water interfacial tension is increased by reducing or eliminating the activity of functional groups acting as surfactants by treating the emulsions with one or more additives of ionic base to increase the hydrophobic characteristics of bitumen droplets in the emulsions and thus increase their attraction to each other and to gas bubbles. Additives effective for this purpose include salts of the Periodic Table's Group II earth alkali metals cations such as magnesium, calcium, strontium, and barium, and Group III metals cations such as aluminum. Mechanical agitation or injection of a gas stream into the destabilized bitumen-eater emulsion may be used to form bitumen-rich froth. The additives used for destabilization of the emulsions also promote flocculation of clay-size particles in the froth and improve the chemistry of the recovered water.

What is claimed is: 
     
         1 . A method for destabilizing an emulsion selected from the group consisting of bitumen-water emulsions and heavy-oil-water emulsions, said method comprising the step of treating the emulsion with a salt of a Period Table Group II earth alkali metal cation selected from the group consisting of cations of magnesium, calcium, strontium, and barium. 
     
     
         2 . A method for destabilizing an emulsion selected from the group consisting of bitumen-water emulsions and heavy-oil-water emulsions, said method comprising the step of treating the emulsion with a salt of a metal cation selected from the group consisting of cations of aluminum, iron, and zinc. 
     
     
         3 . A method for destabilizing an emulsion selected from the group consisting of bitumen-water emulsions and heavy-oil-water emulsions, said method comprising the step of treating the emulsion with an additive selected from the group consisting of hydrochloric acid (HCl), sodium bicarbonate (NaHCO 3 ), calcium chloride (CaCl 2 ), and calcium oxide (CaO). 
     
     
         4 . A method as in  claim 3  wherein the additive comprises lime in the form of calcium oxide (CaO). 
     
     
         5 . A method as in  claim 4  wherein the dosage of calcium oxide in the range between about 50 milligrams per kilogram of emulsion to about 5.0 grams per kilogram of emulsion. 
     
     
         6 . A method as in  claim 5  wherein the dosage of calcium oxide in the range between about 2.5 to about 5.0 grams per kilogram of emulsion. 
     
     
         7 . A method as in  claim 3 , comprising the further step of injecting an unreactive gas into the emulsion to form a bitumen-rich or heavy-oil-rich froth. 
     
     
         8 . A method as in  claim 7  wherein the unreactive gas is selected from the group consisting of air, combustion flue gas, steam, nitrogen, and carbon dioxide. 
     
     
         9 . A method as in  claim 3  wherein the emulsion is a bitumen-water emulsion produced by an oil-sands-ore-water-slurry-based bitumen extraction process. 
     
     
         10 . A method as in  claim 3  wherein the emulsion is a bitumen-water emulsion produced by a steam-assisted bitumen recovery process. 
     
     
         11 . A method as in  claim 10  wherein the steam-assisted bitumen recovery process is the steam-assisted gravity drainage (SAGD) process. 
     
     
         12 . A method as in  claim 10  wherein the steam-assisted bitumen recovery process is the cyclic steam stimulation (CSS) process.