Use of Organic Acids or a Salt Thereof in Surfactant-Based Enhanced Oil Recovery Formulations and Techniques

Abstract

The present disclosure provides a surfactant formulation for use in treating and recovering fossil fluid from a subterranean formation. The surfactant formulation includes a nonionic surfactant, organic acid selected from citric acid, diglycolic acid, glycolic acid and a salt thereof and injection water. The surfactant formulation may be injected into one or more injection wells located within the subterranean formation and fossil fluids can then be subsequently recovered from one or more producing wells

What is claimed is: 
     
         1 . A surfactant formulation for treating a fossil fluid-bearing subterranean formation comprising a nonionic surfactant, organic acid selected from citric acid, diglycolic acid, glycolic acid and a salt thereof, and injection water. 
     
     
         2 . The surfactant formulation according to  claim 1 , wherein the nonionic surfactant comprises a compound having a hydrophobic head that is a natural or synthetically-based alkyl group or an alkylaryl group and a hydrophilic tail that is an alkoxylate group. 
     
     
         3 . The surfactant formulation according to  claim 1 , wherein the nonionic surfactant is an alkoxylated alkylphenol or an alkoxylated alcohol comprising one or more repeating C 1  to C 4  alkylene oxide groups. 
     
     
         4 . The surfactant formulation according to  claim 1 , wherein the nonionic surfactant is an alkoxylated alkylphenol having one or more linear or branched C 1  to C 25  alkyl groups attached. 
     
     
         5 . The surfactant formulation according to  claim 1 , wherein the nonionic surfactant is an alkoxylated linear or branched saturated aliphatic alcohol compound comprising 5 to 30 carbon atoms. 
     
     
         6 . The surfactant formulation according to  claim 1 , wherein the nonionic surfactant is a an alkoxylated Guerbet alcohol of formula (I)
   R 2 —O—BO t —PO u —EO w —H   (I)
   
       wherein R 2  corresponds to an aliphatic, branched hydrocarbon group C n H 2n+1  derived from a Guerbet alcohol where n corresponds to the number of carbon atoms and may range from 12 to 36; BO corresponds to a butoxy group; t corresponds to the number of butoxy groups present and may range from 0 to 50; PO corresponds to a propoxy group; u corresponds to the number of propoxy groups present and may range from 0 to 50; EO corresponds to an ethoxy group; and w corresponds to the number of ethoxy groups present and may range from 0 to 50 with the proviso that t+u+w≧1. 
     
     
         7 . The surfactant formulation according to  claim 1 , wherein the organic acid is glycolic acid or a glycolic acid salt. 
     
     
         8 . The surfactant formulation according to  claim 7 , wherein the glycolic acid salt is sodium glycolate and/or disodium glycolate. 
     
     
         9 . The surfactant formulation according to  claim 1 , wherein the injection water is seawater, brine, fresh water from an aquifer, river or lake, or a mixture thereof. 
     
     
         10 . A method of preparing a surfactant formulation for treating a fossil fluid-bearing subterranean formation comprising mixing a nonionic surfactant with an organic acid selected from citric acid, diglycolic acid, glycolic acid and a salt thereof and injection water. 
     
     
         11 . A process for recovering fossil fluids from a fossil fluid-bearing subterranean formation comprising injecting the surfactant formulation of  claim 1  into one or more injection wells such that oil is subsequently produced from one or more producing wells. 
     
     
         12 . A surfactant package for treating a fossil fluid-bearing subterranean formation comprising a nonionic surfactant and an organic acid selected from citric acid, diglycolic acid, glycolic acid and a salt thereof. 
     
     
         13 . The surfactant package according to  claim 12 , wherein the nonionic surfactant is an alkoxylated alkylphenol having one or more linear or branched C 1  to C 25  alkyl groups attached. 
     
     
         14 . The surfactant formulation according to  claim 12 , wherein the nonionic surfactant is an alkoxylated linear or branched saturated aliphatic alcohol compound comprising 5 to 30 carbon atoms. 
     
     
         15 . The surfactant formulation according to  claim 12 , wherein the nonionic surfactant is a an alkoxylated Guerbet alcohol of formula (I)
   R 2 —O—BO t —PO u —EO w —H   (I)
   
       wherein R 2  corresponds to an aliphatic, branched hydrocarbon group C n H 2n+1  derived from a Guerbet alcohol where n corresponds to the number of carbon atoms and may range from 12 to 36; BO corresponds to a butoxy group; t corresponds to the number of butoxy groups present and may range from 0 to 50; PO corresponds to a propoxy group; u corresponds to the number of propoxy groups present and may range from 0 to 50; EO corresponds to an ethoxy group; and w corresponds to the number of ethoxy groups present and may range from 0 to 50 with the proviso that t+u+w≧1. 
     
     
         16 . The surfactant formulation according to  claim 12 , wherein the organic acid is glycolic acid or a glycolic acid salt.