Weak gel system for chemical enhanced oil recovery

A method of treating a wellbore or subterranean hydrocarbon-bearing formation to increase hydrocarbon recovery from the formation, the method comprising:

• introducing either a water soluble acrylamide polymer and a non-metallic organic crosslinking agent, or a crosslinkable acrylamide polymer, into an injection fluid entering the wellbore or the formation;
• wherein the water soluble acrylamide polymer and the non-metallic organic crosslinking agent or the crosslinkable acrylamide polymer form a flowable crosslinked polymer in the presence of the injection fluid flowing within the formation and the flowable crosslinked polymer pushes the hydrocarbon out of the formation while the flowable crosslinked polymer continues to flow through the formation;
• the non-metallic organic crosslinking agent comprising a polymeric polyamine which is either (i) a reaction product of a polymerization mixture comprised of at least one monomer of Formulae II or a salt thereof;
• or (ii) comprised of at least one structural unit of Formulae IIA, wherein Formulae II, and IIA have the following structures:
• wherein:
• R1 is each independently hydrogen, a protecting group, or alkyl;
• and
• R2, R3, R4, R5, R6 and R7 are each independently hydrogen, alkyl, or alkoxylalkyl;
• and
• the crosslinkable acrylamide polymer comprising a reaction product of a polymerization mixture comprised of at least one acrylamide monomer and at least one monomer of the Formula II or a salt thereof,
• wherein if the non-metallic organic crosslinking agent comprises diallylamine as the structure of Formula II, then the non-metallic organic crosslinking agent comprises a copolymer of diallylamine with an acrylamide or an acrylic acid;
• or a terpolymer of diallylamine with an acrylamide and an acrylic acid;
• or a copolymer of diallylamine with 2-acrylamido-2-methylpropane sulfonic acid (“AMPS”) or N-vinylpyrrolidone (“NVP”);
• or a terpolymer of diallylamine with AMPS and NVP.