Compositions and methods for diverting injected fluids to achieve improved hydrocarbon fluid recovery
View Patent ↗The present disclosure is directed to compositions and methods that may be used for enhanced oil recovery, for modifying the permeability of subterranean formations and for increasing the mobilization and/or recovery rate of hydrocarbon fluids present in the formations. The compositions may include, for example, expandable cross linked polymeric microparticles having an unexpanded volume average particle size diameter of from about 0.05 to about 5,000 microns and a cross linking agent content of from about 100 to about 200,000 ppm of hydrolytically labile silyl ester or silyl ether crosslinkers and from 0 to about 300 ppm of non-labile crosslinkers.
1. A composition comprising highly cross linked expandable polymeric microparticles comprising labile and non-labile crosslinkers having unexpanded volume average particle size diameters of about 0.05 to about 5,000 microns and a cross linking agent content of from 0 to about 300 ppm of non-labile cross linking agents and from about 100 to about 200,000 ppm oflabile crosslinking agents, wherein said labile crosslinking agents comprise one or more hydrolytically labile silyl ether or silyl ester crosslinkers and wherein said particle size is constrained by cross-linking with said labile and non-labile crosslinkers wherein said labile cross links begin to break upon exposure to pre-selected conditions of temperature and/or pH, thereby permitting the microparticles to expand in a controlled fashion.
2. The composition of claim 1 wherein said hydrolytically labile crosslinkers have formula R 1 R 2 R 3 Si[OSiR 4 R 5 ] n R 6 wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are independently selected from vinyl, vinyloxy, allyoxy, acryloxy, methacryloxy, allyl, alkyl, aryl, alkoxy, utylalkyl and —OC(O)R 6 where n is 0-100, provided that said crosslinkers comprise at least two vinyl, vinyloxy, allyoxy, acryloxy, methacryloxy or allyl groups, or a mixture thereof.
3. The composition of claim 1 , wherein the unexpanded volume average particle size diameter is from about 0.1 to about 3 microns.
4. The composition of claim 1 , wherein the unexpanded volume average particle size diameter is from about 0.1 to about 1 micron.
5. The composition of claim 1 , comprising cross linked anionic, cationic, amphoteric, ion-pair or betaine-containing polymeric microparticles.
6. The composition of claim 2 wherein R 1 , R 2 , R 4 and R 5 are alkyl and R 3 and R 6 are independently selected from —CH 2 —CH═CH 2 and —O—CH 2 —CH═CH 2 .
7. The composition of claim 1 , wherein the composition is in the forin of an emulsion or aqueous suspension.
8. The composition of claim 7 , wherein the cross linked polymeric microparticle is anionic.
9. The composition of claim 8 , wherein the anionic polymeric microparticle is prepared by free-radical polymerization from about 95 to about 10 mole percent of nonionic monomers and from about 5 to about 90 mole percent anionic monomers.
10. The composition of claim 9 , wherein the nonionic monomer is acrylamide.
11. The composition of claim 10 , wherein the anionic monomer is 2-acrylamido-2-methyl-1-propanesulfonic acid.
12. The composition of claim 1 , wherein the non-labile cross linker is methylene. bisacrylamide.
13. The composition of claim 1 further comprising one or more labile crosslinkers.
14. The composition of claim 1 further comprising one or more highly cross linked expandable polymeric microparticles having unexpanded volume average particle size diameters of about 0.05 to about 5,000 microns and a cross linking agent content of from 0 to about 300 ppm of non-labile cross linking agent and from about 100 to about 200,000 ppm of labile crosslinking agent.