Crosslinked polymers for use in crude oil recovery

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#FIG. 1 is a schematic of the injection system wherein the crosslinking agent and the uncrosslinked polymer are pumped separately into a long tubing where reaction to form the crosslinked water-soluble polymer takes place.

#FIG. 2 is a schematic of the apparatus used in the screen factor test described in Example 1.

#FIG. 3 is a graph of the screen factor in seconds versus the time in hours that the aluminum citrate and hydrolyzed polyvinylamide have been mixed.

#Corresponding reference characters indicate corresponding parts throughout the drawings.

#The properties of an aqueous flooding fluid comprising these mobility control polymers can be improved by having an improved pressure differential and improved oil recovery as compared to an uncrosslinked polymer at a higher concentration. The mobility control polymers can be used in methods for increasing recovery of crude oil from a subterranean hydrocarbon containing formation. The mobility control polymers increase the apparent viscosity by increasing the hydrodynamic volume of the crosslinked water-soluble polymer as compared to the uncrosslinked water-soluble polymer.

#The methods of increasing recovery of crude oil from a subterranean hydrocarbon containing formation comprise injecting an aqueous flooding fluid into a well that is in contact with the subterranean hydrocarbon-containing formation, the aqueous flooding fluid comprising injection water and a mobility control agent. The mobility control agent comprises a crosslinked water-soluble polymer wherein the crosslinked water-soluble polymer is derived from reacting a crosslinking agent with a polymer and the crosslinking agent comprises a polyvalent metal ion having a weight/weight ratio of polymer to crosslinking agent of at least 60:1.