Hydrocarbons

Abstract

A method of removing hydrocarbon-based adherent, for example bitumen, from a solid substrate, for example tar sands comprises contacting the solid substrate which includes associated hydrocarbon-based adherent with a treatment formulation which includes a polymeric material which includes vinylalcohol and vinylacetate repeat units. The polymeric material may be a 70-95 mole % hydrolysed polyvinylalcohol.

1 - 23 . (canceled) 
     
     
         24 . A method of removing hydrocarbon-based adherent from a solid substrate, the method comprising contacting a solid substrate which includes associated hydrocarbon-based adherent with a treatment formulation which includes a polymeric material which includes vinylalcohol and vinylacetate repeat units. 
     
     
         25 . The method according to  claim 24 , wherein said hydrocarbon-based adherent is a heavy oil having an API gravity less than 30°, for example less than 10°. 
     
     
         26 . The method according to  claim 24 , wherein said solid substrate comprises a naturally-occurring substrate. 
     
     
         27 . The method according to  claim 24 , wherein said treatment formulation has an Interfacial Tension (IFT) measured against a sample of the hydrocarbon-based adherent to be removed in the range 2 to 20 mN/m; and/or a surface tension (in the absence of any oil) at 25° C. in the range 35 to 66 mN/m. 
     
     
         28 . The method according to  claim 24 , wherein said treatment formulation comprises at least 95 wt %, especially at least 98 wt %, water; and at least 0.1 wt % and less than 2 wt %, of said polymeric material. 
     
     
         29 . The method according to  claim 24 , wherein said polymeric material has a weight average molecular weight (Mw) of less than 200,000; and the Mw is at least 5,000. 
     
     
         30 . The method according to  claim 24 , wherein said adherent is a bitumen having an API of less than 10° and said polymeric material has a weight average molecular weight of greater than 50,000; and preferably less than 300,000. 
     
     
         31 . The method according to  claim 24 , wherein in said polymeric material the mole % of vinylalcohol repeat units divided by the mole % of vinylacetate repeat units is in the range 1.5 to 19. 
     
     
         32 . The method according to  claim 24 , wherein said polymeric material comprises at least 50 mole % of vinylalcohol repeat units; and at least 2 mole % of vinylacetate repeat units. 
     
     
         33 . The method according to  claim 24 , wherein said polymeric material comprises 80 to 95 mole % of vinylalcohol repeat units; and at least 5 mole % of vinylacetate repeat units. 
     
     
         34 . The method according to  claim 24 , wherein the sum of the mole % of vinylalcohol and vinylacetate repeat units in said polymeric material is at least 80 mole %. 
     
     
         35 . The method according to  claim 24 , wherein said polymeric material comprises 70-95 mole % hydrolysed polyvinylalcohol. 
     
     
         36 . The method according to  claim 24 , wherein said treatment formulation has a viscosity at 25° C. and 100 s −1  of greater than 0.98 cP; and/or said treatment formulation has a pH in the range 5 to 9. 
     
     
         37 . The method according to  claim 24 , wherein said solid substrate and/or said treatment formulation are agitated after contact so as to mix the treatment formulation and solid substrate. 
     
     
         38 . The method according to  claim 24 , wherein the method comprises extracting a mass of solid substrate containing an adherent which is a crude oil from the ground wherein said mass includes at least 3 wt % of crude oil; at least 3 wt % of water; and at least 5 wt % of naturally-occurring particulate material which includes at least some sand. 
     
     
         39 . The method according to  claim 24 , wherein the mass is extracted and is contacted with treatment formulation at the surface to remove oil from the solids included in the mass. 
     
     
         40 . The method according to  claim 24 , which comprises removing bitumen from oil sands. 
     
     
         41 . The method according to  claim 40 , wherein said oil sands comprise a mass which includes 75 to 85 wt % of inorganic materials and 10 to 20 wt % of bitumen. 
     
     
         42 . The method according to  claim 40 , wherein after removal of the oil sands, the oil sands are contacted with said treatment formulation thereby to form a slurry which is allowed to separate and includes forming a bitumen froth. 
     
     
         43 . The method according to  claim 24 , wherein said method comprises a CHOPS process. 
     
     
         44 . The method according to  claim 24 , wherein said method comprises treating waste sand from a CHOPS well with said treatment formulation. 
     
     
         45 . A method of recovering oil from a subterranean formation which comprises:
 (i) extracting a mass comprising oil mixed with indigenous sand from the formulation;   (ii) contacting the mass with a treatment formulation;   (iii) separating the sand from oil and components of the treatment formulation to produce two parts, one being sand-rich and the other comprising oil and components of the treatment formulation;   (iv) treating the dispersion to produce an oil-rich part; and separating the oil-rich and water-rich parts from one another, for example by delivery of the parts into separate receptacles or conduits.