Crosslinking of swellable polymer with pei

Abstract

The invention is directed to stable and labile crosslinked water swellable polymeric microparticles that can be further gelled, methods for making same, and their various uses in the hygiene and medical arts, gel electrophoresis, packaging, agriculture, the cable industry, information technology, in the food industry, papermaking, use as flocculation aids, and the like. More particularly, the invention relates to a composition comprising expandable polymeric microparticles having labile crosslinkers and stable crosslinkers, said microparticle mixed with a fluid and an unreacted tertiary crosslinker comprising PEI or other polyamine based tertiary crosslinker that is capable of further crosslinking the microparticle on degradation of the labile crosslinker and swelling of the particle, so as to form a stable gel. A particularly important use is as an injection fluid in petroleum production, where the expandable polymeric microparticles are injected into a well and when the heat and/or pH of the well cause degradation of the labile crosslinker and when the microparticle expands, the tertiary crosslinker crosslinks the polymer to form a stable gel, thus diverting water to lower permeability regions and improving oil recovery.

1 . A method of increasing the recovery of hydrocarbon fluids in a subterranean formation, comprising:
 a) injecting into the subterranean formation a mixture comprising water and a composition comprising:
 i) expandable microparticles comprising acrylamide-based polymers crosslinked with labile crosslinkers and stable cross linkers, wherein said acrylamide-based polymers are capable of undergoing transamidation reactions; 
 ii) an unreacted tertiary crosslinker comprising polyethyleneimine (“PEI”), wherein said tertiary crosslinker is capable of further covalently crosslinking said microparticles by transamidation after degradation of said labile crosslinker to form a stable gel; 
   b) aging said mixture at 190° C. until it gels, and;   c) producing hydrocarbon from said subterranean formation.   
     
     
         2 . A method of increasing the recovery of hydrocarbon fluids in a subterranean formation, comprising:
 a) injecting into the subterranean formation a mixture comprising water and expandable acrylamide-based polymeric microparticles having labile crosslinkers and stable crosslinkers, and   b) injecting an unreacted tertiary crosslinker into the subterranean formation, wherein said tertiary crosslinker is selected from the group consisting of polyalkyleneimine, a polyethyleneimine, a polyalkylenepolyamine, polyethyleneimine, simple polyamines, methylene diamine, ethylene diamine, hexamethylene diamine, and hexamethylene triamine.   
     
     
         3 . The method of  claim 2 , wherein steps a) and b) occur at different times or the same time. 
     
     
         4 . The method of  claim 2 , further comprising step c) aging said mixture at 190° C. until it gels.