Process For Producing Natural Gas And Natural Gas Condensate From Underground Gas Condensate Deposits

Abstract

A process for producing natural gas and/or natural gas condensate from an underground gas condensate deposit comprising a gas mixture having retrograde condensation characteristics, comprising at least the process steps of: a) sinking at least one production well into the underground gas condensate deposit and producing natural gas and/or natural gas condensate from the underground production well through the at least one production well, b) injecting a solution (S) comprising a solvent and urea through the at least one production well into the underground gas condensate deposit, c) waiting for a rest phase in which the urea present in the solution (S) is hydrolyzed, d) producing natural gas and/or natural gas condensate from the underground gas condensate deposit through the at least one production well.

1 . A process for producing natural gas and/or natural gas condensate from an underground gas condensate deposit comprising a gas mixture having retrograde condensation characteristics, comprising at least the process steps of
 a) sinking at least one production well into the underground gas condensate deposit and producing natural gas and/or natural gas condensate from the underground production well through the at least one production well,   b) injecting a solution (S) comprising a solvent and urea through the at least one production well into the underground gas condensate deposit,   c) waiting for a rest phase in which the urea present in the solution (S) is hydrolyzed,   d) producing natural gas and/or natural gas condensate from the underground gas condensate deposit through the at least one production well.   
     
     
         2 . The process according to  claim 1 , wherein the underground gas condensate deposit has a deposit temperature (T D ) in the range from 60 to 200° C., preferably in the range from 70 to 150° C., more preferably in the range from 80 to 140° C. and especially in the range from 85 to 120° C. 
     
     
         3 . The process according to  claim 1 , wherein the solution (S) comprises 50 to 79% by weight of urea and 21 to 50% by weight of solvent, the solvent comprising water, alcohol or a mixture of water and alcohol, based in each case on the total weight of the solution (S). 
     
     
         4 . The process according to  claim 1 , wherein the solution (S) has a crystallization temperature (T C ) below the deposit temperature (T D ) of the underground gas condensate deposit. 
     
     
         5 . The process according to  claim 1 , wherein the solution (S) is heated prior to or during the injection in process step b). 
     
     
         6 . The process according to  claim 1 , wherein the deposit temperature (T D ) of the underground gas condensate deposit is higher than the crystallization temperature (T C ) of the solution (S). 
     
     
         7 . The process according to  claim 1 , wherein the solution (S) is injected in process step b) with a temperature higher than the crystallization temperature (T C ), and the deposit temperature (T D ) of the underground gas condensate deposit is higher than the crystallization temperature (T C ) of the solution (S). 
     
     
         8 . The process according to  claim 1 , wherein the underground gas condensate deposit prior to performance of process step b) has a critical region (CR) at least partly blocked by liquid natural gas condensate. 
     
     
         9 . The process according to  claim 1 , wherein the duration of the rest phase is selected such that the urea originally present in the solution (S) is fully hydrolyzed in the underground gas condensate deposit to carbon dioxide and ammonia, and 60 to 100% by weight of the water originally present in the solution (S) is consumed. 
     
     
         10 . The process according to  claim 1 , wherein the at least one production well is closed during the rest phase in process step c). 
     
     
         11 . The process according to  claim 1 , wherein the solution (S) comprises
 50 to <76.9% by weight of urea,   >0 to 35% by weight of alcohol and   15 to 50% by weight of water.   
     
     
         12 . The process according to  claim 1 , wherein the solution (S) comprises
 50 to <76.9% by weight of urea,   KA % by weight of alcohol and   15 to 50% by weight of water,   where KA is defined by the following formula:
   KA=100% by weight−(KH*1.3)
 
   in which KA states the amount of alcohol present in the solution (S) in % by weight and KH states the amount of urea present in the solution (S) in % by weight.   
     
     
         13 . The process according to  claim 1 , wherein the solution (S) is injected in process step b) in volumes corresponding to not more than the pore volume of the critical region (CR). 
     
     
         14 . The process according to  claim 1 , wherein the solution (S) is injected in process step b) in volumes which lead, in the hydrolysis of urea, to a gas volume of carbon dioxide and ammonia corresponding at least to the pore volume of the critical region (CR). 
     
     
         15 . (canceled)