US2012325483A1PendingUtilityA1

Combined miscible or near miscible gas and asp flooding for enhanced oil recovery

35
Individually held — no corporate assignee on recordPriority: Oct 2, 2009Filed: Sep 10, 2010Published: Dec 27, 2012
Est. expiryOct 2, 2029(~3.2 yrs left)· nominal 20-yr term from priority
Inventors:Brian Francis Towler
C09K 8/594
35
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Claims

Abstract

A method for enhancing oil recovery by combining miscible or near miscible gas flooding with Alkaline-Surfactant-Polymer (ASP) flooding to produce an enhanced Water-Alternating-Gas (WAG) flooding method is described. The ASP flooding may include individual and combination injections of alkaline, surfactant and polymer. Carbon dioxide may be used as a flood gas. Numerical simulations show that the present method may provide better oil recovery when compared with separate ASP or CO 2 WAG flooding for different depositional environments, as a result of high micro and macro sweep efficiencies plus miscible gas flooding. A significant acceleration and improvement in recovery may be achieved with as small as a 10% pore volume ASP slug size.

Claims

exact text as granted — not AI-modified
1 . A method for enhancing oil recovery from reservoirs, comprising the steps of:
 (a) waterflooding at least a portion of the reservoir;   (b) pressurizing the reservoir with a chosen gas miscible or near miscible with oil remaining behind the waterflooded portion of the reservoir;   (c) flooding the pressurized portion of the reservoir with a solution containing at least one surfactant or at least one polymer; and   (d) flooding the pressurized portion of the reservoir with a solution containing alkali.   
     
     
         2 . The method of  claim 1 , wherein the chosen miscible or near miscible gas comprises carbon dioxide. 
     
     
         3 . The method of  claim 1 , further comprising the step of waterflooding the pressurized portion of the reservoir after said step of pressurizing the reservoir. 
     
     
         4 . The method of  claim 1 , further comprising the step of pressurizing the reservoir with a chosen gas miscible or near miscible with the remaining oil after said step of flooding the pressurized portion of the reservoir with a solution containing at least one surfactant or at least one polymer. 
     
     
         5 . The method of  claim 1 , further comprising the step of producing oil from the reservoir during said at least one of said steps. 
     
     
         6 . A method for enhancing oil recovery from reservoirs, comprising the steps of:
 (a) waterflooding at least a portion of the reservoir;   (b) pressurizing the reservoir with a chosen gas miscible or near miscible with oil remaining behind the waterflooded portion of the reservoir;   (c) waterflooding the pressurized portion of the reservoir;   (d) flooding the pressurized portion of the reservoir with a solution containing alkali; and   (e) flooding the pressurized portion of the reservoir with a solution containing at least one surfactant or at least one polymer.   
     
     
         7 . The method of  claim 6 , wherein the chosen miscible or near miscible gas comprises carbon dioxide. 
     
     
         8 . The method of  claim 6 , further comprising the step of pressurizing the reservoir with a chosen gas miscible or near miscible with the remaining oil after said step of flooding the pressurized portion of the reservoir with a solution containing alkali. 
     
     
         9 . The method of  claim 6 , further comprising the step of producing oil from the reservoir during at least one of said steps. 
     
     
         10 . A method for enhancing oil recovery from reservoirs, comprising the steps of:
 (a) waterflooding at least a portion of the reservoir;   (b) pressurizing the reservoir with a chosen gas miscible or near miscible with oil remaining behind the waterflooded portion of the reservoir;   (c) waterflooding the pressurized portion of the reservoir;   (d) flooding the pressurized portion of the reservoir with a solution containing alkali; and   (e) flooding the pressurized portion of the reservoir with a solution containing at least one surfactant and at least one polymer.   
     
     
         11 . The method of  claim 10 , wherein the chosen miscible or near miscible gas comprises carbon dioxide. 
     
     
         12 . The method of  claim 10 , further comprising the step of pressurizing the reservoir with a chosen gas miscible or near miscible with the remaining oil after said step of flooding the pressurized portion of the reservoir with a solution containing alkali. 
     
     
         13 . The method of  claim 10 , further comprising the step of producing oil from the reservoir during at least one of said steps. 
     
     
         14 . A method for enhancing oil recovery from reservoirs, comprising the steps of:
 (a) waterflooding at least a portion of the reservoir;   (b) pressurizing the reservoir with a chosen gas miscible or near miscible with oil remaining behind the waterflooded portion of the reservoir; and   (c) flooding the pressurized portion of the reservoir with a solution containing alkali, at least one surfactant and at least one polymer.   
     
     
         15 . The method of  claim 14 , wherein the chosen miscible or near miscible gas comprises carbon dioxide. 
     
     
         16 . The method of  claim 14 , further comprising the step of waterflooding the pressurized portion of the reservoir after said step of pressurizing the reservoir with a chosen gas miscible or near miscible with the remaining oil. 
     
     
         17 . The method of  claim 16 , further comprising the step of pressurizing the reservoir with a chosen gas miscible or near miscible with the remaining oil after said step of waterflooding the pressurized portion of the reservoir. 
     
     
         18 . The method of  claim 14 , further comprising the step of producing oil from the reservoir during at least one of said steps. 
     
     
         19 . A method for enhancing oil recovery from reservoirs, comprising the steps of:
 (a) flooding at least a portion of the reservoir with an alkaline solution;   (b) pressurizing the reservoir with a chosen gas miscible or near miscible with oil remaining behind the flooded portion of the reservoir; and   (c) flooding the pressurized portion of the reservoir with a solution containing at least one surfactant or at least one polymer.   
     
     
         20 . The method of  claim 19 , wherein the chosen miscible or near miscible gas comprises carbon dioxide. 
     
     
         21 . The method of  claim 19 , further comprising the step of pressurizing the reservoir with a chosen gas miscible or near miscible with the remaining oil after said step of flooding the pressurized portion of the reservoir with a solution containing at least one surfactant or at least one polymer. 
     
     
         22 . The method of  claim 19 , further comprising the step of producing oil from the reservoir during at least one of said steps. 
     
     
         23 . A method for enhancing oil recovery from reservoirs, comprising the steps of:
 (a) flooding at least a portion of the reservoir with a solution containing at least one surfactant or at least one polymer;   (b) pressurizing the reservoir with a chosen gas miscible or near miscible with oil remaining behind the flooded portion of the reservoir; and   (c) flooding the pressurized portion of the reservoir with a solution containing alkali.   
     
     
         24 . The method of  claim 23 , wherein the chosen miscible or near miscible gas comprises carbon dioxide. 
     
     
         25 . The method of  claim 23 , further comprising the step of waterflooding the pressurized portion of the reservoir after said step of pressurizing the reservoir with a chosen gas miscible or near miscible with the remaining oil. 
     
     
         26 . The method of  claim 23 , further comprising the step of producing oil from the reservoir during at least one of said steps. 
     
     
         27 . A method for enhancing oil recovery from reservoirs, comprising the steps of:
 (a) flooding at least a portion of the reservoir with a solution containing at least one surfactant and at least one polymer;   (b) pressurizing the reservoir with a chosen gas miscible or near miscible with oil remaining behind the flooded portion of the reservoir; and   (c) flooding the pressurized portion of the reservoir with a solution containing alkali.   
     
     
         28 . The method of  claim 27 , wherein the chosen miscible or near miscible gas comprises carbon dioxide. 
     
     
         29 . The method of  claim 27 , further comprising the step of waterflooding the pressurized portion of the reservoir after said step of pressurizing the reservoir with a chosen gas miscible or near miscible with the remaining oil. 
     
     
         30 . The method of  claim 27 , further comprising the step of producing oil from the reservoir during at least one of said steps. 
     
     
         31 . A method for enhancing oil recovery from reservoirs, comprising the steps of:
 (a) flooding at least a portion of the reservoir with a solution containing alkali, at least one surfactant and at least one polymer;   (b) pressurizing the reservoir with a chosen gas miscible or near miscible with oil remaining behind the flooded portion of the reservoir; and   (c) waterflooding the pressurized portion of the reservoir.   
     
     
         32 . The method of  claim 31 , wherein the chosen miscible or near miscible gas comprises carbon dioxide. 
     
     
         33 . The method of  claim 31 , further comprising the step of pressurizing the reservoir with a chosen gas miscible or near miscible with the remaining oil after said step of waterflooding the pressurized portion of the reservoir. 
     
     
         34 . The method of  claim 31 , further comprising the step of producing oil from the reservoir during at least one of said steps.

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