Water flooding method for secondary hydrocarbon recovery

Abstract

A water flooding composition in a method of secondary hydrocarbon recovery. The water flooding composition includes water and a thickening polymer. The thickening polymer includes a hydroxyethyl cellulose backbone polymer having a molecular weight of between about 1,000,000 and about 2,000,000 and a hydrophobic modifier. The hydrophobic modifier has a substitution level in the thickening polymer of between about 0.1 percent and about 2 percent by weight of the thickening polymer. The hydrophobic modifier is an alkyl hydrocarbon based material containing between about 10 and about 24 unsubstituted carbon atoms per group. The thickening polymer has a concentration in the water flooding composition of between about 0.01 percent and about 1 percent by weight of the water flooding composition. The water flooding composition is formulated within these ranges so that the water flooding composition has a suitable viscosity/mobility and so that the water flooding composition is injectable.

1 . In a method of secondary hydrocarbon recovery of a type which comprises passing a water flooding composition through a subterranean formation containing a hydrocarbon deposit, the method characterized by the water flooding composition being comprised of water and a thickening polymer, the thickening polymer having a concentration of between 0.01 percent and 1 percent by weight of the water flooding composition, the thickening polymer comprising:
 (a) a hydroxyethyl cellulose backbone polymer having a molecular weight of between 1,000,000 and 2,000,000; and   (b) a hydrophobic modifier in a substitution level in the thickening polymer of between 0.1 percent and 2 percent by weight of the thickening polymer, wherein the hydrophobic modifier is comprised of an alkyl hydrocarbon based material containing between 10 and 24 unsubstituted carbon atoms per group;   
       wherein the water flooding composition is formulated to have a viscosity of between 2 mPa·s and 100 mPa·s and to be injectable into the subterranean formation. 
     
     
         2 . The method as claimed in  claim 1  wherein the concentration of the thickening polymer in the water flooding composition is between 0.05 percent and 0.25 percent by weight of the water flooding composition. 
     
     
         3 . The method as claimed in  claim 2  wherein the alkyl hydrocarbon based material of the hydrophobic modifier contains between 12 and 18 unsubstituted carbon atoms per group. 
     
     
         4 . The method as claimed in  claim 3  wherein the substitution level of the hydrophobic modifier in the thickening polymer is between 0.1 percent and 1.5 percent by weight of the thickening polymer. 
     
     
         5 . The method as claimed in  claim 4  wherein the hydrocarbon deposit has a mobility, wherein the water flooding composition has a mobility, and wherein a ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 100:1. 
     
     
         6 . The method as claimed in  claim 5  wherein the water flooding composition is adapted to be capable of being passed through a permeable test medium from an upstream end of the permeable test medium to a downstream end of the permeable test medium, wherein the permeable test medium has an initial permeability of less than 10 darcies, such that the thickening polymer has an initial concentration in the water flooding composition at the upstream end of the permeable test medium and a final concentration in the water flooding composition at the downstream end of the permeable test medium, and such that the final concentration of the thickening polymer in the water flooding composition is greater than ninety percent of the initial concentration of the thickening polymer in the water flooding composition. 
     
     
         7 . The method as claimed in  claim 6  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 50:1. 
     
     
         8 . The method as claimed in  claim 7  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 10:1. 
     
     
         9 . The method as claimed in  claim 8  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 2:1. 
     
     
         10 . The method as claimed in  claim 5  wherein the water flooding composition is adapted to be capable of being passed through a permeable test medium from an upstream end of the permeable test medium to a downstream end of the permeable test medium, wherein the permeable test medium has an initial permeability of less than 10 darcies, such that the water flooding composition has an initial viscosity at the upstream end of the permeable test medium and a final viscosity at the downstream end of the permeable test medium, and such that the final viscosity of the water flooding composition is greater than ninety percent of the initial viscosity of the water flooding composition. 
     
     
         11 . The method as claimed in  claim 10  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 50:1. 
     
     
         12 . The method as claimed in  claim 11  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 10:1. 
     
     
         13 . The method as claimed in  claim 12  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 2:1. 
     
     
         14 . The method as claimed in  claim 4  wherein the water flooding composition is adapted to be capable of being passed through a permeable test medium from an upstream end of the permeable test medium to a downstream end of the permeable test medium, wherein the permeable test medium has an initial permeability of less than 10 darcies, such that the thickening polymer has an initial concentration in the water flooding composition at the upstream end of the permeable test medium and a final concentration in the water flooding composition at the downstream end of the permeable test medium, and such that the final concentration of the thickening polymer in the water flooding composition is greater than ninety percent of the initial concentration of the thickening polymer in the water flooding composition. 
     
     
         15 . The method as claimed in  claim 14  wherein the water flooding composition has a viscosity of between 2 mPa·s and 50 mPa·s. 
     
     
         16 . The method as claimed in  claim 4  wherein the water flooding composition is adapted to be capable of being passed through a permeable test medium from an upstream end of the permeable test medium to a downstream end of the permeable test medium, wherein the permeable test medium has an initial permeability of less than 10 darcies, such that the water flooding composition has an initial viscosity at the upstream end of the permeable test medium and a final viscosity at the downstream end of the permeable test medium, and such that the final viscosity of the water flooding composition is greater than ninety percent of the initial viscosity of the water flooding composition. 
     
     
         17 . The method as claimed in  claim 16  wherein the water flooding composition has a viscosity of between 2 mPa·s and 50 mPa·s. 
     
     
         18 . The method as claimed in  claim 4  wherein the hydroxyethyl cellulose backbone polymer of the water flooding composition has a molecular weight of 1,300,000. 
     
     
         19 . The method as claimed in  claim 18  wherein the hydrocarbon deposit has a mobility, wherein the water flooding composition has a mobility, and wherein a ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 100:1. 
     
     
         20 . The method as claimed in  claim 19  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 50:1. 
     
     
         21 . The method as claimed in  claim 20  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 10:1. 
     
     
         22 . The method as claimed in  claim 21  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 2:1. 
     
     
         23 . The method as claimed in  claim 18  wherein the water flooding composition has a viscosity of between 2 mPa·s and 50 mPa·s. 
     
     
         24 . The method as claimed in  claim 4  wherein the alkyl hydrocarbon based material of the hydrophobic modifier is comprised of dodecyl tetradecyl glycidyl ether. 
     
     
         25 . The method as claimed in  claim 24  wherein the hydrocarbon deposit has a mobility, wherein the water flooding composition has a mobility, and wherein a ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 100:1. 
     
     
         26 . The method as claimed in  claim 25  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 50:1. 
     
     
         27 . The method as claimed in  claim 26  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 10:1. 
     
     
         28 . The method as claimed in  claim 27  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 2:1. 
     
     
         29 . The method as claimed in  claim 24  wherein the water flooding composition has a viscosity of between 2 mPa·s and 50 mPa·s. 
     
     
         30 . The method as claimed in  claim 4  wherein the substitution level of the hydrophobic modifier in the thickening polymer is between 0.7 percent and 1 percent by weight of the thickening polymer. 
     
     
         31 . The method as claimed in  claim 30  wherein the hydrocarbon deposit has a mobility, wherein the water flooding composition has a mobility, and wherein a ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 100:1. 
     
     
         32 . The method as claimed in  claim 31  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 50:1. 
     
     
         33 . The method as claimed in  claim 32  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 10:1. 
     
     
         34 . The method as claimed in  claim 33  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 2:1. 
     
     
         35 . The method as claimed in  claim 30  wherein the water flooding composition has a viscosity of between 2 mPa·s and 50 mPa·s. 
     
     
         36 . The method as claimed in  claim 4  wherein the concentration of the thickening polymer in the water flooding composition is 0.2 percent by weight of the water flooding composition. 
     
     
         37 . The method as claimed in  claim 36  wherein the hydrocarbon deposit has a mobility, wherein the water flooding composition has a mobility, and wherein a ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 100:1. 
     
     
         38 . The method as claimed in  claim 37  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 50:1. 
     
     
         39 . The method as claimed in  claim 38  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 10:1. 
     
     
         40 . The method as claimed in  claim 39  wherein the ratio of the mobility of the water flooding composition to the mobility of the hydrocarbon deposit is no greater than 2:1. 
     
     
         41 . The method as claimed in  claim 36  wherein the water flooding composition has a viscosity of between 2 mPa·s and 50 mPa·s. 
     
     
         42 . The method as claimed in  claim 4  wherein the hydroxyethyl cellulose backbone polymer of the water flooding composition has a molecular weight of 1,300,000, wherein the alkyl hydrocarbon based material of the hydrophobic modifier is comprised of dodecyl tetradecyl glycidyl ether, wherein the substitution level of the hydrophobic modifier in the thickening polymer is between 0.7 percent and 1 percent by weight of the thickening polymer, and wherein the concentration of the thickening polymer in the water flooding composition is 0.2 percent by weight of the water flooding composition. 
     
     
         43 . The method as claimed in  claim 42  wherein the water of the water flooding composition is comprised of a brine solution. 
     
     
         44 . The method as claimed in  claim 43  wherein the brine solution is comprised of one percent sodium chloride by weight of the brine solution. 
     
     
         45 . A method of preparing a water flooding composition for use in a method of secondary hydrocarbon recovery of a type which comprises passing the water flooding composition through a subterranean formation containing a hydrocarbon deposit, the method comprising:
 (a) selecting a hydroxyethyl cellulose backbone polymer having a molecular weight of between 1,000,000 and 2,000,000;   (b) selecting a hydrophobic modifier comprised of an alkyl hydrocarbon based material containing between 10 and 24 unsubstituted carbon atoms per group;   (c) providing a thickening polymer comprising the hydroxyethyl cellulose backbone polymer and the hydrophobic modifier in a substitution level in the thickening polymer of between 0.1 percent and 2 percent by weight of the thickening polymer; and   (d) combining the thickening polymer with water to provide the water flooding composition, wherein the thickening polymer has a concentration of between 0.1 percent and 1 percent by weight of the water flooding composition;   
       wherein the water flooding composition has a viscosity of between 2 mPa·s and 100 mPa·s and is injectable into the subterranean formation.