Composition and method for recovering hydrocarbon fluids from a subterranean reservoir
View Patent ↗A composition comprising crosslinked expandable polymeric microparticles capable of hydrolysis at or below neutral pH and a method of modifying the permeability to water of a subterranean formation by introducing such compositions into the subterranean formation is disclosed and claimed. This invention further relates to compositions and methods for the recovery of hydrocarbon fluids from a subterranean reservoir or formation subjected to CO 2 or CO 2 Water Alternating Gas flooding at low pH and increases the mobilization and/or recovery rate of hydrocarbon fluids present in the subterranean formations.
1. A composition comprising: crosslinked expandable polymeric microparticles having
(i) an unexpanded volume average particle size diameter from about 0.05 to about 2,000 microns and (ii) a crosslinking agent content from about 50 to about 200,000 ppm of at least one labile crosslinker based on a molar ratio of said polymeric microparticles capable of cleavage, at or below neutral pH and from 0 to about 900 ppm of at least one non-labile crosslinker based on a molar ratio,
wherein the at least one labile crosslinker is selected from at least one of the following structures 1-26.
2. The composition of claim 1 , wherein at least a portion of the crosslinked expandable polymeric microparticles is highly crosslinked.
3. The composition of claim 1 , wherein the unexpanded volume average particle size diameter is from about 0.05 to about 10 microns.
4. The composition of claim 1 , wherein the unexpanded volume average particle size diameter is from about 0.05 to about 1 micron.
5. The composition of claim 1 , wherein the at least one labile crosslinker comprises a crosslinker with at least two functional sites.
6. The composition of claim 1 , wherein the expandable polymeric microparticle comprises at least one of the following properties: anionic, amphoteric, ion-pair, betaine-containing, and combinations thereof.
7. The composition of claim 1 , further comprising an emulsion, a dry powder, or an aqueous suspension.
8. The composition of claim 1 , wherein the crosslinked expandable polymeric microparticles are 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.
9. The composition of claim 7 , wherein the anionic monomer is 2-acrylamido-2-methyl-1-propanesulfonic acid and the nonionic monomer is acrylamide.
10. The composition of claim 1 , wherein said at or below neutral pH is from about pH 3 to about pH 6.