Synthesis of Degradable Polymers Downhole for Oilfield Applications

Abstract

A method is given for polymerizing monomers downhole to create well treatment polymers. The monomers each contain two polymerizable groups and a degradable group or groups which allow the polymer to degrade under downhole conditions, for example by hydrolysis. Polymerization downhole allows easier, more precise, placement of polymer. Polymer obtained from monomers pumped downhole may be used, for example, for fluid diversion plugs, isolation plugs, formation consolidation, flowback control, and fluid loss control. Synthesized polymer may form gels, films, solids or other structure in treated wellbores, fractures, and/or formations. After the desired effect is achieved, the deposited polymer degrades and the polymer degradation products dissolve, leaving the wellbore, fracture and/or formation clean, with no damage that might have decreased fluid flow.

1 . A method comprising pumping a fluid comprising a polymerizable monomer downhole, initiating downhole polymerization, and allowing decomposition of the resulting polymer under downhole conditions. 
     
     
         2 . The method of  claim 1  used for downhole treatment. 
     
     
         3 . The method of  claim 1  or  2 , wherein the monomer comprises at least two polymerizable chemical groups and one or more degradable chemical groups. 
     
     
         4 . The method of  claim 1  or  2 , wherein the monomer comprises one or more water-soluble groups linking the polymerizable and degradable groups. 
     
     
         5 . The method of  claim 4 , wherein the water soluble linking groups comprise oligoethyleneglycol, glycerol, phosphate, or mixtures of these. 
     
     
         6 . The method of  claim 1  or  2 , wherein the monomer comprises one or more precursors to water-soluble groups linking the polymerizable and degradable groups. 
     
     
         7 . The method of  claim 1  or  2 , wherein the polymerizable groups comprise acrylic, methacrylic, aziridine, oxirane, isocyanate, vinyl, and mixtures of these groups. 
     
     
         8 . The method of  claim 1  or  2 , wherein the fluid comprises a second, different, monomer comprising at least two polymerizable chemical groups and one or more degradable chemical groups. 
     
     
         9 . The method of  claim 8 , wherein the fluid comprises a nucleophilic monomer and an electrophilic monomer. 
     
     
         10 . The method of  claim 1  or  2 , wherein the fluid further comprises acrylic acid, methacrylic acid, or both. 
     
     
         11 . The method of  claim 1  or  2 , wherein the monomers for polymerization are diacrylic ethers or anhydrides or dimethylacrylic ethers or anhydrides. 
     
     
         12 . The method of  claim 1  or  2 , wherein downhole polymerization of monomer is emulsion polymerization. 
     
     
         13 . The method of  claim 1  or  2 , wherein the fluid further comprises a polymerization initiator. 
     
     
         14 . The method of  claim 1  or  2 , wherein the fluid further comprises a chain transfer agent. 
     
     
         15 . The method of  claim 1  or  2 , wherein the polymerization is nitroxide mediated free radical polymerization. 
     
     
         16 . The method of  claim 1  or  2 , wherein the fluid further comprises a free radical trap. 
     
     
         17 . The method of  claim 1  or  2 , wherein the degradation of polymer is caused by an increase in temperature. 
     
     
         18 . The method of  claim 1  or  2 , wherein the degradation of polymer is caused by a change in fluid pH. 
     
     
         19 . The method of  claim 1  or  2 , wherein the degradation of polymer is caused by a polymer degradation agent pumped downhole before or after the fluid comprising monomer. 
     
     
         20 . The method of  claim 1  or  2 , wherein the fluid further comprises a polymer degradation agent. 
     
     
         21 . The method of  claim 1  or  2 , wherein the fluid further comprises a surfactant. 
     
     
         22 . The method of  claim 1  or  2 , wherein the fluid further comprises a fiber. 
     
     
         23 . The method of  claim 1  or  2 , wherein the monomer comprises a Mannich reaction product. 
     
     
         24 . The method of  claim 1  or  2 , wherein the fluid is an emulsion. 
     
     
         25 . The method of  claim 2 , wherein the treatment includes at least one of diversion, isolation, formation consolidation, flowback control, or fluid loss control.