Method of removing filter cake

Abstract

A filter cake deposited by a drilling fluid, drill-in fluid or fluid loss control pill may be removed from a wellbore by introducing into the wellbore a dispersing agent of an organic amino phosphonic acid, ester or salt. The dispersing agent forms a dispersion containing at least a portion of the drilled solids. The dispersing agent may be introduced into the wellbore as a component of a filter cake removal treatment fluid or either prior to or after introduction of the filter cake removal treatment fluid.

1 . In a method of removing a filter cake containing drilled and deposited solids from a wellbore by introducing into the wellbore a treatment fluid capable of degrading the filter cake, the improvement comprising further introducing into the wellbore and/or treatment fluid a dispersing agent and digesting at least a portion of the filter cake with the treatment fluid and dispersing agent and further forming a dispersion containing at least a portion of the drilled and/or deposited solids, the dispersing agent being an organic amino phosphonic acid, ester or salt thereof. 
     
     
         2 . The method of  claim 1 , wherein the dispersing agent is an aminoalkyl phosphonic acid, ester or salt thereof. 
     
     
         3 . The method of  claim 2 , wherein the dispersing agent is a polyaminomethylene phosphonate having from 2 to about 10 nitrogen atoms. 
     
     
         4 . The method of  claim 3 , wherein the dispersing agent is selected from the group consisting of ethylenediamine tetra(methylene phosphonate), diethylenetriamine penta(methylene phosphonate) and triamine- and tetraamine- polymethylene phosphonates having between from about 2 to about 8 methylene groups between each N atom. 
     
     
         5 . The method of  claim 3 , wherein the dispersing agent is either bis-aminoalkyl ether phosphonate or a mixture of a monoalkanol amine phosphonate and a bis-hexalkylene triamine phosphonate. 
     
     
         6 . The method of  claim 1 , wherein the dispersing agent is a polyphosphonic acid, ester or salt of the formula: 
       
         
           
           
               
               
           
         
       
       wherein:
 each Z is independently —CHR 1 PO 3 (R)(R) or H, provided that at least two Zs are —CHR 1 PO 3 (R)(R); 
 each R 1  is independently selected from —H, —CH 3 , —C(R 2 )(R 2 )(R 2 ), C 6 H 5 . —C(R 2 )(R 2 )-, —SO 3 H 2  and —SO 3 M 2 ; 
 each R 2  is independently selected from —H, —CH 3  and —C 2 H 5 ; 
 each R is independently selected from —H, —CH 3 , —C 2 H 5  and M; 
 each M is independently selected from an alkali metal, ½ of an alkaline earth metal, 1/n of a transition metal with +n charge, an ammonium ion and hydrogen ion; 
 n is between from about 1 to about 6, preferably from about 2 to about 4; 
 m is between from about 1 to about 6, preferably from about 2 to about 4; 
 a is between from about 1 to about 10, preferably from about 2 to about 4; 
 b is between from about 1 to about 10, preferably from about 2 to about 4; 
 x is between from 0 to about 6, preferably from 0 to about 3; and 
 y is between from 0 to about 6, preferably from 0 to about 2. 
 
     
     
         7 . The method of  claim 1 , wherein the agent is bis-aminoethyl ether phosphonate or a mixture of bis-hexamethylene triamine phosphonate and monoethanol amine phosphonate and, optionally, bis-hexamethylene triamine pentaphosphonate. 
     
     
         8 . The method of  claim 1 , wherein the dispersing agent is a component of the treatment fluid. 
     
     
         9 . A method of removing a filter cake containing drilled and deposited solids from a wellbore comprising:
 (a) introducing into the wellbore a treatment fluid comprising a dispersing agent of an organic amino phosphonic acid, ester or salt thereof;   (b) digesting at least a portion of the filter cake with the treatment fluid;   (c) forming a dispersion of drilled and deposited solids wherein at least a portion of the drilled and deposited solids separate from the filter cake; and   (d) removing the dispersion containing the separated drilled and deposited solids and at least a portion of the filter cake from the wellbore.   
     
     
         10 . The method of  claim 9 , wherein the dispersing agent is selected from the group consisting of a bis-aminoalkyl ether phosphonate; and a mixture of a monoalkanol amine phosphonate and a bis-hexalkylene triamine phosphonate; 
     
     
         11 . The method of  claim 10 , wherein the dispersing agent is bis-aminoethyl ether phosphonate or a mixture of monoethanol amine phosphonate and bis-hexamethylene triamine phosphonate and, optionally, bis-hexamethylene triamine pentaphosphonate. 
     
     
         12 . The method of  claim 11 , wherein the dispersing agent is bis-aminoethyl ether phosphonate. 
     
     
         13 . The method of  claim 11 , wherein the dispersing agent is a mixture of bis-hexamethylene triamine phosphonate and monoethanol amine phosphonate and, optionally, bis-hexamethylene triamine pentaphosphonate. 
     
     
         14 . A method of increasing the flow of production fluids from or injection fluids into a subterranean formation by removing a filter cake having fine particulates from the wellbore, the method comprising:
 (a) introducing into the wellbore a treatment fluid and a dispersing agent, wherein the dispersing agent is introduced into the wellbore either before or after introduction of the treatment fluid or as a component of the treatment fluid;   (b) digesting or degrading at least a portion of the filter cake with the treatment fluid and dispersing agent; and   (c) forming a dispersion of fine particulates and dispersing agent; and   (d) removing the dispersion and at least a portion of the filter cake from the wellbore   
       wherein the dispersing agent is an organic amino phosphonic acid, ester or salt thereof. 
     
     
         15 . The method of  claim 14 , wherein the dispersing agent is selected from the group consisting of a bis-aminoalkyl ether phosphonate; and a mixture of a monoalkanol amine phosphonate and a bis-hexalkylene triamine phosphonate; 
     
     
         16 . The method of  claim 15 , wherein the dispersing agent is bis-aminoethyl ether phosphonate or a mixture of monoethanol amine phosphonate and bis-hexamethylene triamine phosphonate and, optionally, bis-hexamethylene triamine pentaphosphonate. 
     
     
         17 . The method of  claim 15 , wherein the dispersing agent is bis-aminoethyl ether phosphonate. 
     
     
         18 . The method of  claim 15 , wherein the dispersing agent is a mixture of bis-hexamethylene triamine phosphonate and monoethanol amine phosphonate and, optionally, bis-hexamethylene triamine pentaphosphonate. 
     
     
         19 . A method of removing a filter cake containing drilled and deposited solids from a wellbore comprising:
 (a) introducing into the wellbore a filter cake removal treatment fluid and a dispersing agent selected from the group consisting of organic amino phosphonic acids, esters and salts thereof;   (b) contacting the filter cake with the dispersing agent, digesting a portion of the filter cake and forming a dispersion containing separated drilled and deposited solids and dispersing agent;   (c) removing the resulting dispersion away from the vicinity of the filter cake; and   (d) further digesting the filter cake with the filter cake removal treatment fluid and removing the filter cake from the wellbore.   
     
     
         20 . The method of  claim 19 , wherein the dispersing agent is introduced into the wellbore as a component of the filter cake removal treatment fluid. 
     
     
         21 . The method of  claim 19 , wherein the dispersing agent is introduced into the wellbore either prior to or after introduction of the filter cake removal treatment fluid. 
     
     
         22 . The method of  claim 19 , wherein the filter cake removal treatment fluid contains a member selected from the group consisting of enzymes, acids and oxidizers. 
     
     
         23 . A method of removing a filter cake containing drilled and deposited solids from a wellbore by:
 (a) digesting at least a portion of the filter cake and forming a dispersion containing separated drilled and deposited solids by introducing into the wellbore a filter cake removal treatment fluid and a dispersing agent;   (c) removing the dispersion formed in step (a) away from the vicinity of the filter cake; and   (d) removing the filter cake from the wellbore   
       wherein the dispersing agent is an organic amino phosphonic acid, ester or salt thereof. 
     
     
         24 . The method of  claim 23 , wherein the dispersing agent is introduced into the wellbore at the same time as introduction of the filter cake removal treatment fluid. 
     
     
         25 . The method of  claim 23 , wherein the dispersing agent is introduced into the wellbore either before or after introduction of the filter cake removal treatment fluid. 
     
     
         26 . The method of  claim 23 , wherein the filter cake removal treatment fluid contains a member selected from the group consisting of enzymes, acids and oxidizers. 
     
     
         27 . A method of removing a filter cake containing drilled and deposited solids from a wellbore by digesting the filter cake and removing the drilled and deposited solids from the wellbore, the method consisting essentially of introducing into the wellbore a filter cake removal treatment fluid and a dispersing agent, forming a dispersion of the separated drilled and deposited solids and dispersing agent and then removing the dispersion and the filter cake from the wellbore, wherein the dispersing agent is an organic amino phosphonic acid, ester or salt thereof.