Solvent-Induced Separation of Oilfield Emulsions

Abstract

Systems and methods for separation of oleaginous fluids, aqueous fluids, and solids from drilling or other oilfield emulsions by solvent extraction. A method for separation of oilfield emulsions comprising: providing an oilfield emulsion prepared for use in a wellbore and/or recovered from a wellbore; mixing the oilfield emulsion with at least a solvent to form at least a mixture; and separating the mixture to at least partially recover an oleaginous phase of the oilfield emulsion.

What is claimed is: 
     
         1 . A separation system comprising:
 a mixing unit fluidically coupled to a separation feed and a solvent feed, wherein the separation feed comprises an oilfield emulsion; and   a separation unit fluidically coupled to the mixing unit.   
     
     
         2 . The separation system of  claim 1 , wherein the mixing unit is fluidically coupled to a retention pit, wherein the retention pit comprises the separation feed. 
     
     
         3 . The separation system of  claim 1 , wherein the oilfield emulsion comprises a solids-stabilized emulsion. 
     
     
         4 . The separation system of  claim 1 , wherein the oilfield emulsion comprises an invert emulsion drilling fluid. 
     
     
         5 . The separation system of  claim 1 , wherein the oilfield emulsion further comprises an oleaginous continuous phase comprising an oleaginous liquid selected from the group consisting of a diesel oil, a crude oil, a paraffin oil, a mineral oil, an olefin, an ester, an amide, an amine, a polyolefin, a polydiorganosiloxane, a siloxane, an organosiloxane, an ether, an acetal, a dialkylcarbonate, a hydrocarbon, and combinations thereof. 
     
     
         6 . The separation system of  claim 5 , wherein a volume to volume ratio of the oleaginous continuous phase to the discontinuous phase is in the range of from 20:80 to 95:5. 
     
     
         7 . The separation system of  claim 1 , wherein the solvent feed comprises a solvent or a mixture of solvents. 
     
     
         8 . The separation system of  claim 1 , wherein the solvent feed comprises a paraffinic hydrocarbon having from four carbons to eight carbons. 
     
     
         9 . The separation system of  claim 1 , further comprising a CO 2  mixing unit fluidically coupled to a carbon dioxide feed and fluidically coupled to the mixing unit for receiving a mixture of the separation feed and the solvent feed. 
     
     
         10 . The separation system  claim 1 , wherein the CO 2  mixing unit comprises a column for counter-currently contacting the carbon dioxide feed and the mixture of the separation feed and the solvent feed. 
     
     
         11 . The separation system of  claim 1 , further comprising a solvent flash tank fluidically coupled to the separation unit. 
     
     
         12 . The separation system of  claim 11 , further comprising a carbon dioxide flash tank fluidically coupled to the solvent flash tank. 
     
     
         13 . The separation system of  claim 1 , wherein the mixing unit is configured to mix the separation feed and the solvent feed to produce a mixed fluid and wherein the separation unit is configured to separate the mixed fluid into at least a solids-laden fraction and an oleaginous-solvent fraction. 
     
     
         14 . The separation system of  claim 13 , wherein the solids-laden fraction comprises barite. 
     
     
         15 . The separation system of  claim 13 , wherein the separation unit is further configured to separate the oleaginous-solvent fraction to produce a recovered solvent and an oleaginous-enriched phase. 
     
     
         16 . A separation system comprising:
 a mixing unit fluidically coupled to a separation feed and a solvent feed, wherein the separation feed comprises an oleaginous continuous phase, a discontinuous phase, and wellbore cuttings, wherein the solvent feed comprises a solvent, and wherein the mixing unit is configured to mix the separation feed and the solvent feed to produce a mixture; and   a separation unit fluidically coupled to the mixing unit configured receive the mixture and contact the mixture with liquid carbon dioxide.   
     
     
         17 . The separation system of  claim 16 , wherein the separation unit is further configured to produce a lights overflow stream comprising at least a portion of the solvent, at least a portion of the carbon dioxide, at least a portion of the oleaginous continuous phase, and at least a portion of the discontinuous phase. 
     
     
         18 . The separation system of  claim 17 , further comprising a CO 2  flash tank configured to receive the lights overflow stream and generate a recovered carbon dioxide stream and a solvent-oleaginous stream, and wherein the CO 2  flash tank is fluidically coupled to a condenser configured to condense at least a portion of the recovered carbon dioxide stream to produce a recycled liquid carbon dioxide. 
     
     
         19 . The separation system of  claim 18 , further comprising a solvent flash tank configured to receive the solvent-oleaginous stream and generate a recovered solvent stream and an oleaginous-enriched stream, wherein the solvent flash tank is fluidically coupled to a compressor configured to compress the recovered solvent to produce a recycled solvent. 
     
     
         20 . The separation system of  claim 16 , wherein the separation unit is further configured to produce an underflow stream comprising the wellbore cutting solids.