Process for producing mineral oil from an underground deposit

Abstract

A process for producing mineral oil, in which an aqueous flooding medium comprising water, a glucan, urea and optionally surfactants is injected into the mineral oil formation and mineral oil is withdrawn from the formation through at least one production well, wherein the formation has a temperature of at least 60° C. The formulation forms in situ foams in the formation under the influence of the formation temperature.

1 . A process for producing mineral oil from an underground mineral oil deposit into which at least one production well and at least one injection well have been sunk, each of which is connected to the deposit, said process comprising at least one process step (B) in which mineral oil is produced by injection of an aqueous flooding medium comprising water-soluble thickening polymers through the injection well and withdrawing mineral oil through the production well, wherein
 the temperature during process step (B) at least in a partial region of the mineral oil formation between the injection and production wells is at least 60° C. and the aqueous flooding medium comprises, as well as water, at least
 a glucan (G) with a β-1,3-glycosidically linked main chain and side groups β-1,6-glycosidically bonded thereto, said glucan having a weight-average molecular weight M w  of 1.5*10 6  to 25*10 6  g/mol, and 
 urea. 
   
     
     
         2 . The process according to  claim 1 , wherein the aqueous flooding medium used in process step (B) comprises 15 to 300 g/l of urea and 0.1 to 5 g/l of the glucan (G). 
     
     
         3 . The process according to  claim 2 , wherein the aqueous flooding medium used in process step (B) additionally comprises 50 to 250 g/l of an ammonium salt. 
     
     
         4 . The process according to  claim 2 , wherein the aqueous flooding medium used in process step (B) additionally comprises 0.1 to 5 g/l of a surfactant. 
     
     
         5 . The process according to  claim 1 , wherein the temperature at least in a partial region of the mineral oil formation between the injection and production wells is at least 80° C. 
     
     
         6 . The process according to  claim 1 , wherein the temperature at least in a partial region of the mineral oil formation between the injection and production wells is 80° C. to 120° C. 
     
     
         7 . The process according to  claim 1 , wherein the process comprises an additional process step (A) which is performed before process step (B), and in which either an aqueous flooding medium (process step (A1)) or steam (process step (A2)) is injected. 
     
     
         8 . The process according to  claim 1 , wherein the process comprises an additional process step (C) which is performed after process step (B), and in which either an aqueous flooding medium (process step (C1)) or steam (process step (C2)) is injected. 
     
     
         9 . The process according to  claim 7 , which involves process step (Al) wherein the aqueous flooding medium injected comprises, as well as water, at least one glucan (G), with the proviso that the amount of this glucan (G) is such that the viscosity of the aqueous flooding medium injected in process step (A1) is less than the viscosity of the aqueous flooding medium injected in process step (B). 
     
     
         10 . The process according to  claim 8 , which involves process step (C1) wherein the aqueous flooding medium injected comprises, as well as water, at least one glucan (G), with the proviso that the amount of this glucan (G) is such that the viscosity of the aqueous flooding medium injected in process step (C1) is greater than the viscosity of the aqueous flooding medium injected in process step (B). 
     
     
         11 . The process according to  claim 7 , wherein the aqueous flooding media injected in process steps (A1) and/or (C1) have a temperature of at least 80° C. 
     
     
         12 . The process according to  claim 7 , wherein either steam or an aqueuos flooding medium with a temperature of at least 80° C. is injected in process step (A), and wherein an aqueous flooding medium with a temperature of less than 40° C. is additionally injected between process steps (A) and (B). 
     
     
         13 . The process according to  claim 8 , wherein either steam or an aqueuos flooding medium with a temperature of at least 80° C. is injected in process step (C), and wherein an aqueous flooding medium with a temperature of less than 40° C. is additionally injected between process steps (B) and (C). 
     
     
         14 . The process according to  claim 12 , wherein the aqueous flooding media injected between (A) and (B) and/or (B) and (C) comprise at least one glucan (G). 
     
     
         15 . The process according to  claim 14 , which comprises at least one additional process step (D) for blocking of highly permeable regions of the underground mineral oil formation, and in which an aqueous flooding medium which is injected comprises, as well as water, at least
 a glucan (G) with a β-1,3-glycosidically linked main chain and side groups β-1,6-glycosidically bonded thereto, said glucan having a weight-average molecular weight M w  of 1.5*10 6  to 25*10 6  g/mol,   urea, and   at least one water-soluble aluminum(III) salt and/or a partly hydrolyzed aluminum(III) salt.   
     
     
         16 . The process according to  claim 15 , wherein process step (D) is performed after process step (B) and then the process is continued with another performance of process step (B).