Method for pre-treatment of subterranean sites adjacent to water injection wells

Abstract

A method to improve the effectiveness of MEOR or bioremediation processes has been disclosed. In this method toxic chemicals accumulated in subterranean sites adjacent to the water injection wells are either dispersed or removed prior to introduction of microbial inocula for enhanced microbial oil recovery or bioremediation of these sites.

1 . A bioremediation method comprising the steps of:
 a) treating a subterranean site in a zone adjacent to a water injection well with a detoxifying agent wherein, prior to the treatment, corrosion inhibitors and their degradation products have been adsorbed into the zone and have accumulated to concentrations that are toxic to microorganisms used in microbial enhanced oil recovery and/or bioremediation processes, and thereby have formed a toxic zone; and   b) adding an inoculum of microorganisms to the water injection well wherein the microorganisms comprise one or more species useful for bioremediation selected from:  Pseudomonas, Corynebacteria, Achromobacter, Acinetobacter, Arthrobacter, Bacillus, Nocardia , and  Vibrio;      
       wherein the corrosion inhibitor is an inorganic compound selected from the group consisting of chlorine, hypochlorite, bromine, hypobromide, chlorine dioxide, hydrazine, anthraquinone, phosphates, and salts containing chrome, molybdenum, zinc, nitrates, nitrites and sodium sulfite. 
     
     
         2 . The method of  claim 1  wherein the detoxifying agent of (a) is also a dispersing agent. 
     
     
         3 . The method of  claim 2  wherein the dispersing agent is an acid selected from the group consisting of hydrochloric acid, nitric acid, hydrofluoric acid, acetic acid and oxalic acid. 
     
     
         4 . The method of  claim 3  wherein the dispersing agent causes disassociation of the corrosion inhibitor from the subterranean site adjacent to the water injection well and disperses and dilutes it such that the corrosion inhibitor becomes non-toxic to the microorganisms and the subterranean site adjacent to the water injection well is detoxified. 
     
     
         5 . The method of  claim 3  wherein the dispersing agent is hydrochloric acid. 
     
     
         6 . The method of  claim 3  wherein the dispersing agent is nitric acid. 
     
     
         7 . The method of  claim 3  wherein the acid is at a concentration from about 0.1 weight percent to about 20 weight percent. 
     
     
         8 . The method of  claim 1  wherein the corrosion inhibitor is a growth inhibitor of sulfate reducing bacteria. 
     
     
         9 . The method of  claim 4  wherein the microorganisms colonize the detoxified subterranean site adjacent to the water injection well to perform bioremediation.