Composition and method for water and gas shut-off in subterranean formations

Abstract

A composition useful for subterranean water or gas shut off applications includes organosilane-modified colloidal silica and an accelerator. The accelerator includes one or more organic or inorganic salts. A method of using a composition, including an organosilane-modified colloidal silica and an accelerator, includes forming a fluid system that is flowed to a formation in a subterranean zone, such as through a wellbore, where the composition forms a gel to plug the formation and shut off water flow into the wellbore.

1 . A composition, comprising:
 a modified colloidal silica, wherein at least a portion of surface silanol groups of an unmodified colloidal silica are replaced with an organosilane moiety; and   an accelerator that is an organic or inorganic salt comprising one or more cations;   wherein a silica to cation molar ratio (X) of the composition is defined by the equation:   
       
         
           
             
               X 
               = 
               
                 
                   N 
                   silica 
                 
                 
                   
                     N 
                     cations 
                   
                   × 
                   
                     Z 
                     6 
                   
                 
               
             
           
         
         wherein X is between about 8 and about 50, N silica  is the total number of moles of silica in the composition, N cations  is the total number of moles of cations in the composition, and Z is the charge on the cation; and 
         wherein the accelerator is present in an amount of between about 2 to about 30 wt % of the composition and a silica content of the composition is between about 10 to about 55 wt % of the unmodified silica. 
       
     
     
         2 . The composition of  claim 1 , wherein the organosilane moiety comprises a silicon atom bound to one, two, or three R 1  groups by a direct Si—C bond, wherein:
 each R 1  is independently selected from the group consisting of i) alkyl, ii) epoxy alkyl, iii) alkenyl, iv) aryl, v) heteroaryl, vi) C 1-6  alkylaryl, and vii) C 1-6  alkylheteroaryl, any of which are optionally substituted with one or more groups selected from among ER 2 , isocyanate, and isocyanurate; 
 E is absent or is a linking group selected from the group consisting of —O—, —S—, —OC(O)—, —C(O)—, —C(O)O—, —C(O)OC(O)—, —N(R 3 )—, —N(R 3 )C(O)—, —N(R 3 )C(O)N(R 3 )—, and —C(O)N(R 3 )—; 
 R 2  is selected from the group consisting of hydrogen, F, Cl, Br, alkyl, alkenyl, aryl, heteroaryl, C 1-3  alkylaryl, and C 1-3  alkylheteroaryl, and is optionally substituted with one or more groups selected from the group consisting of hydroxyl, F, Cl, Br, epoxy, —OR 3 , and —N(R 3 ) 2 ; and 
 R 3  is H or C 1-6  alkyl. 
 
     
     
         3 . The composition of  claim 2  wherein R 1  is a hydrophilic moiety or becomes hydrophilic after hydrolysis. 
     
     
         4 . The composition of  claim 3 , wherein R 1  comprises a member selected from the group consisting of carboxyl, ester, epoxy, acyloxy, ketone, aldehyde, (meth)acryloxy, amido, hydroxyl, thiol, amino, ureido, isocyanate, and isocyanurate. 
     
     
         5 . The composition of  claim 2 , wherein R 1  comprises an epoxy group or one or more hydroxyl groups. 
     
     
         6 . The composition of  claim 5 , wherein R 1  comprises an ER 2  substituent, wherein E is —O— and R 2  is selected from the group consisting of C 1-8 -epoxyalkyl, substituted C 1-8 -epoxyalkyl, and a hydroxyl-substituted alkyl. 
     
     
         7 . The composition of  claim 2 , wherein R 1  is a hydrophilic group comprising at least one heteroatom selected from O and N, and comprising no more than three consecutive alkylene (CH 2 ) groups. 
     
     
         8 . The composition of  claim 7 , wherein R 1  is selected from the group consisting of 3-glycidoxypropyl, 2,3-dihydroxypropoxypropyl, 2,3-dihydroxypropyl, and 2,3-dihydroxypropoxypropyl. 
     
     
         9 . The composition of  claim 2 , wherein the modified colloidal silica is prepared by contacting the unmodified colloidal silica with an organosilane reactant, wherein the organosilane reactant is selected from the group consisting of a compound having the formula T 4-y Si—[R 1 ] y , a siloxane having the formula [R 1 ] b T 3-b Si{—O—SiT 2-c [R 1 ] c } a —O—SiT 3-b [R 1 ] b , and a disilazane having the formula {[R 1 ] b T 3-b Si} 2 —NH, wherein:
 y is from 1 to 3; 
 each a is independently from 0 to 5; 
 each b is independently from 1 to 3; 
 c is 1 or 2; and 
 each T is independently selected from the group consisting of halide, hydroxyl, C 1-6  alkoxy, and C 1-6  haloalkoxy. 
 
     
     
         10 . The composition of  claim 1 , wherein the accelerator comprises one or more members selected from the group consisting of halides, silicates, sulfates, nitrates, carbonates, carboxylates, oxalates, sulfides, and hydroxides. 
     
     
         11 . The composition of  claim 10 , wherein the accelerator comprises at least one hydroxide and at least one silicate. 
     
     
         12 . The composition of  claim 1 , wherein a cation of the one or more cations of the accelerator is selected from the group consisting of alkali metal ions, alkaline earth metal ions, hydrogen ions, ammonium ions, primary organoammonium ions, secondary organoammonium ions, tertiary organoammonium ions, and quaternary organoammonium ions. 
     
     
         13 . The composition of  claim 1 , wherein a cation of the one or more cations of the accelerator is monovalent. 
     
     
         14 . The composition of  claim 13 , wherein the monovalent cation is an alkali metal cation. 
     
     
         15 . The composition of  claim 14 , wherein the monovalent cation is a sodium cation. 
     
     
         16 . The composition of  claim 14 , wherein the monovalent cation is a potassium cation. 
     
     
         17 . The composition of  claim 1 , wherein a pH of the composition is between about 6 and about 11. 
     
     
         18 . The composition of  claim 1 , wherein a degree of surface modification (DM) of the organosilane-modified colloidal silica is between about 0.8 and about 4 molecules per nm 2 , and is defined by the equation: 
       
         
           
             
               DM 
               = 
               
                 
                   AN 
                   organosilane 
                 
                 
                   ( 
                   
                     
                       S 
                       silica 
                     
                     × 
                     
                       M 
                       silica 
                     
                     × 
                     
                       10 
                       18 
                     
                   
                   ) 
                 
               
             
           
         
         wherein:
 A is Avogadro's constant; 
 N organosilane  is a number of moles of organosilane reactant used; 
 S silica  is a surface area of the silica in the colloidal silica, in m 2  g −1 ; and 
 M silica  is a mass of silica in the colloidal silica, in g. 
 
       
     
     
         19 . The composition of  claim 18 , wherein the DM is between about 1 and about 2. 
     
     
         20 . The composition of  claim 1 , wherein the accelerator causes or facilitates a reaction between the modified colloidal silica particles in the composition to form the gelled composition.