Imidazolium based ionic liquid for enhanced oil recovery applications

1 . A method of enhanced oil recovery, comprising:

injecting a solution comprising an imidazolium based ionic liquid and an aqueous liquid into an underground geological formation comprising crude oil and carbonate rock,

wherein the imidazolium based ionic liquid is selected from the group consisting of 1-dodecyl-3-ethyl-imidazolium bromide and 1-dodecyl-3-(carboxymethyl)-imidazolium bromide, and

wherein the aqueous liquid is at least one selected from a group consisting of water, a saline solution having a salinity of 1 to 300 kppm and a seawater having a salinity of 20 to 50 kppm;

flooding a portion of the underground geological formation with the solution at a temperature of 80 to 150° C. under a pressure of 1500 to 3000 psi to displace the crude oil from the carbonate rock; and

extracting the crude oil from the underground geological formation.

2 . The method of claim 1 , wherein the imidazolium based ionic liquid comprises 1-dodecyl-3-(carboxymethyl)-imidazolium bromide which is obtained by a process comprising:

reacting bromoacetic acid with n-dodecyl imidazole at an elevated temperature to form 1-dodecyl-3-(carboxymethyl)-imidazolium bromide in the form of powder.

3 . The method of claim 1 , wherein the imidazolium based ionic liquid comprises 1-dodecyl-3-ethyl-imidazolium bromide which is obtained by a process comprising:

reacting 1-bromoethane with n-dodecyl imidazole at an elevated temperature to form 1-dodecyl-3-ethyl-imidazolium bromide in the form of powder.

4 . The method of claim 1 , wherein the imidazolium based ionic liquid is thermally stable having a weight loss of 1 to 5 wt. % at a temperature of 180 to 200° C. based on the total weight of the imidazolium based ionic liquid.

5 . The method of claim 1 , wherein the imidazolium based ionic liquid has a decomposition temperature of 250 to 300° C.

6 . The method of claim 1 , wherein the imidazolium based ionic liquid comprises 1-dodecyl-3-ethyl-imidazolium bromide having a critical micelle concentration of 10 to 15 mM.

7 . The method of claim 1 , wherein the imidazolium based ionic liquid comprises 1-dodecyl-3-(carboxymethyl)-imidazolium bromide having a critical micelle concentration of 1 to 5 mM.

8 . The method of claim 1 , wherein the solution comprises 1-dodecyl-3-ethyl-imidazolium bromide above critical micelle concentration and water, and

the solution exhibits an air-water interfacial surface tension on the carbonate rock at a pressure of 10 to 30 psi of 30 to 40 mN/m at an ambient temperature and 1 to 6 mN/m at a temperature of 50 to 70° C.

9 . The method of claim 1 , wherein the solution comprises 1-dodecyl-3-(carboxymethyl)-imidazolium bromide above critical micelle concentration and water, and

wherein the solution exhibits an air-water interfacial surface tension on the carbonate rock at a pressure of 10 to 30 psi of 25 to 40 mN/m at an ambient temperature and 1 to 6 mN/m at a temperature of 50 to 70° C.

10 . The method of claim 1 , wherein the solution comprises 1-dodecyl-3-ethyl-imidazolium bromide above critical micelle concentration and seawater, and

wherein the solution exhibits an oil-seawater interfacial surface tension on the carbonated rock of 1 to 5 mN/m at an ambient temperature.

11 . The method of claim 1 , wherein the solution comprises 1-dodecyl-3-(carboxymethyl)-imidazolium bromide above critical micelle concentration and seawater, and

wherein the solution exhibits an oil-seawater interfacial surface tension of 0.1 to 5 mN/m at an ambient temperature.

12 . The method of claim 11 , wherein the carbonate rock exhibits a rock-oil-seawater contact angle of 68° to 72° at a temperature of 70 to 100° C. and a pressure of 1500 to 3000 psi.

13 . The method of claim 12 , wherein the carbonate rock exhibits a contact angle between the carbonate rock, crude oil and seawater of 44° to 48° at a temperature of 70 to 100° C. and a pressure of 1500 to 3000 psi.

14 . The method of claim 1 , wherein the solution comprises 1-dodecyl-3-ethyl-imidazolium bromide at a concentration of 45 to 55 mM and seawater, and

wherein a carbonate rock aged with the solution under ambient conditions for 30 to 40 days exhibits a rock-oil-seawater contact angle of 72° to 76° at a temperature of 20 to 50° C. and a pressure of 1500 to 3000 psi.

15 . The method of claim 1 , wherein the solution comprises 1-dodecyl-3-(carboxymethyl)-imidazolium bromide at a concentration of 45 to 55 mM and seawater, and

wherein a carbonated rock aged with the solution under ambient conditions for 30 to 40 days exhibits a contact angle between the carbonate rock, crude oil and seawater of 48° to 52° at a temperature of 20 to 50° C. and a pressure of 1500 to 3000 psi.

16 . The method of claim 1 , wherein the solution comprises 1-dodecyl-3-ethyl-imidazolium bromide at a concentration of 0.1 to 0.3 mM and seawater, and

an equilibrium oil-seawater interfacial surface tension is reached after 8 to 12 hours after contacting at a value of 12 to 17 mN/m.

17 . The method of claim 1 , wherein the solution comprises 1-dodecyl-3-(carboxymethyl)-imidazolium bromide at a concentration of 0.1 to 0.2 mM and seawater, and

an equilibrium between the carbonated rock, crude oil and seawater on the interfacial surface tension is reached after 2 to 4 hours at a value of 10 to 12 mN/m.

18 . The method of claim 1 , wherein the solution comprises 1-dodecyl-3-(carboxymethyl)-imidazolium bromide at a concentration of 0.2 to 0.3 mM and seawater, and

an equilibrium between the carbonated rock, crude oil and seawater on the interfacial surface tension is reached after 0.5 to 2 hours at a value of 5 to 7 mN/m.

19 . The method of claim 1 , having a cumulative oil recovery rate of 50% to 65% after a duration of 900 to 1200 hours, wherein the imidazolium based ionic liquid is at a concentration of 5 to 10 mM.

20 . The method of claim 1 , having an oil recovery rate of 60 to 80% after a duration of 900 to 1200 hours, wherein the imidazolium based ionic liquid is at a concentration of 40 to 60 mM.