Composition and method for recovering hydrocarbon fluids from a subterranean reservoir
View Patent ↗This invention is directed to a composition comprising expandable polymeric microparticles comprising an interpenetrating polymer network (IPN). The IPN constrains the microparticle to an unexpanded volume average particle size diameter of from about 0.05 to about 5,000 microns. Labile cross-links in the polymers of the IPN are subject to degradation, which results in release of the expandable microparticle so that the microparticle expands. The invention is further directed to the use of the composition for modifying the permeability of subterranean formations and increasing the mobilization and/or recovery rate of hydrocarbon fluids present in the formations.
1. An expandable polymeric microparticle composition comprising an interpenetrating polymer network wherein the interpenetrating polymer network comprises one or more labile polymers and wherein the expandable polymeric microparticles have an unexpanded volume average particle size diameter of from about 0.05 to about 5,000 microns.
2. The composition of claim 1 wherein the labile polymers comprise crosslinked expandable polymeric microparticles.
3. The composition of claim 2 wherein the labile polymers have a cross linking agent content of from about 1000 to about 200,000 ppm of labile cross linkers and from 0 to about 300 ppm of non-labile cross linkers.
4. The composition of claim 3 wherein the labile polymer comprises about 1 to about 25 weight percent of the total polymer content of the microparticles.
5. The composition of claim 3 wherein the labile cross linkers are selected from diacrylates and polyfunctional derivatives of a polyalcohol.
6. The composition of claim 1 wherein the labile polymer comprises one or more ionic cross-linkers.
7. The composition of claim 6 wherein ionic cross-linkers comprise cationic ester monomers.
8. The composition of claim 1 wherein the labile polymers comprise about 1 to about 75 weight percent of the total polymer content of the microparticles.
9. The composition of claim 1 wherein the expandable polymeric microparticles comprise cross-linked latex polymers.
10. A method of modifying the permeability to water of a subterranean formation, comprising injecting into the subterranean formation an expandable polymeric microparticle composition comprising an interpenetrating polymer network wherein the expandable polymeric microparticles have an unexpanded volume average particle size diameter of from about 0.05 to about 5,000 microns and wherein the expandable polymeric microparticles have a smaller diameter than the pores of the subterranean formation and wherein the expandable polymeric microparticles expand under a change in environmental conditions in the subterranean formation.
11. The method of claim 10 wherein the composition is added to injection water as part of a secondary or tertiary process for the recovery of hydrocarbon from the subterranean formation.
12. The method of claim 11 wherein the injection water is added to the subterranean formation at a temperature lower than the temperature of the subterranean formation.
13. The method of claim 10 wherein the change in the environmental conditions results from introducing an activation agent into the formation.
14. The method of claim 13 wherein the activation agent comprises a reducing agent, an oxidation agent, an acid, a base or a biological agent.
15. The method of claim 10 wherein the interpenetrating polymer network further comprises one or more labile polymers.
16. The method of claim 10 wherein said change in the environmental conditions comprises a change in temperature, a change in pressure, a change in pH a change in salinity, a change in shear force or a change in dilution.
17. The method of claim 10 , wherein the composition is added to injection water as part of a secondary or tertiary process for the recovery of hydrocarbon fluids from the subterranean formation.
18. The method of claim 10 , wherein the composition is injected into the subterranean formation as part of a carbon dioxide and water tertiary recovery project.
19. The method of claim 10 , wherein the composition is injected into the subterranean formation as part of a tertiary oil recovery process, one component of which constitutes water injection.
20. The method of claim 10 , wherein the subterranean formation is a sandstone or carbonate hydrocarbon reservoir.