Process for oil recovery using mixed surfactant composition

Abstract

A process for the recovery of oil from subterranean reservoirs by injecting an aqueous fluid containing from about 0.05 to about 2.0% by weight of a bi-functional surfactant or a mixture of surfactants containing one or more of the following structures; Optionally the aqueous fluid may contain mixtures of individual surfactants having carboxylic, and sulfonate or sulfate functionalities. The remainder of the composition includes water or brine, a cosolvent and optionally a viscosity control agent, and optionally an alkali.

1 . A process for the recovery of oil from subterranean reservoirs where a surfactant composition is injected into one or more injection wells and the oil recovered from one or more producing wells where said surfactant composition is comprised of
 a) one or more surfactants having weak and strong anionic functionality groups,   b) an aqueous based solvent,   c) one or more co-surfactants/solvents,   d) optionally a viscosity increasing agent, and   e) optionally an alkali.   
   
   
       2 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the one or more surfactants having weak and strong anionic functionality groups have the weak and strong functionality groups on the same molecule having one of the following structures: 
     
       
         
         
             
             
         
       
       Where m+n is 5 to 28, preferably 9 to 21 and most preferably 15 to 19, 
       X is 0 to 30, preferably 0 to 15, and most preferably 4 to 12, 
       Y is H, CH 3 , or CH 3 CH 2 , 
       M is a mono or divalent cation, preferably H, Na, K, Ca, Mg, NH 4 , and most preferably Na. 
     
   
   
       3 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the weak anionic functionality group is a carboxylate. 
   
   
       4 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the strong anionic functionality group is one or more from the group sulfonate, sulfate. 
   
   
       5 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the one or more surfactants having the weak and strong anionic functionality groups have these functionalities contained on separate surfactants. 
   
   
       6 . The process for the recovery of oil from subterranean reservoirs described in  claim 5  where the one or more surfactants having weak anionic functionality is chosen from the group carboxylated alkylphenol alkoxylates, carboxylated linear alcohol alkoxylates, carboxylated branched alcohol alkoxylates. 
   
   
       7 . The process for the recovery of oil from subterranean reservoirs described in  claim 5  where one or more surfactants having strong anionic functionality is chosen from the group linear alkyl aryl sulfonates, branched alkyl aryl sulfonates, aryl linear alkyl sulfonates, aryl branched alkyl sulfonates, linear alkyl ether sulfates, branched alkyl ether sulfates, linear alkyl ether sulfonates, branched alkyl ether sulfonates, linear alkyl sulfates, branched alkyl sulfates, linear alkyl sulfonates, branched alkyl sulfonates. 
   
   
       8 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the one or more anionic surfactants is present at a concentration from about 0.05, to about 2% by weight preferably from about 0.05 to about 0.5% by weight, and most preferably from about 0.1 to about 0.3% by weight. 
   
   
       9 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the co-surfactants/co-solvents is present at a concentration of 0 to about 50% by weight, preferably 0 to about 25% by weight, and most preferably from about 5 to about 25% by weight. 
   
   
       10 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the viscosity control agent is present at a concentration from 0 and about 10% by weight, preferably from 0 to about 0.3% by weight, and most preferably from 0 to about 0.5% by weight. 
   
   
       11 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the alkali is present at a concentration from 0 to about 10% by weight, preferably from 0 to about 5% by weight, and most preferably from 0 to about 2% by weight. 
   
   
       12 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the co-solvent is chosen from the group: short chain alcohol, glycol, glycerin, glycol ether. 
   
   
       13 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the alkali is chosen from the group: hydroxide, carbonate, silicate, borate. 
   
   
       14 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the aqueous solvent is chosen from the group: water, synthetic brine, injection brine, produced brine. 
   
   
       15 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the one or more injection wells may also serve as the one or more producing wells. 
   
   
       16 . The process for the recovery of oil from subterranean reservoirs described in  claim 1  where the one or more injection wells are different than the one or more producing wells.