Method to improve use of polymers for injectivity profile control in enhanced oil recovery

A method for minimizing formation damage when placing a profile control gel into a formation having varying zones of permeability comprising:

• (a) injecting a first solidifiable gel into a formation which gel comprises hydroxypropyl guar gum and a gel breaker where said gel enters a zone of greater permeability without use of a mechanical packer thereby blocking a lesser permeability zone as a result of a filter cake buildup;
• (b) injecting thereafter a second solidifiable gel lacking a gel breaker into the formation which gel enters said greater permeability zone thereby forcing gel containing said gel breaker deeper into said greater permeability zone which gel comprises;
• (i) water;
• (ii) about 0.2 to about 5.0 wt. percent of a cross-linkable polymer having at least one functional group selected from a member of the group consisting of an amine, an amide, a hydroxyl, or a thiol group;
• and
• (iii) about 0.02 to about 50.0 wt. percent of a partially methylated aminoplast resin which cross-links with said polymer;
• (c) allowing both gels to solidify in the lesser and higher permeability zones;
• and
• (d) causing the solidified gel containing a gel breaker to liquefy thereby unblocking said lesser permeability zone to fluid flow.

A method for minimizing formation damage when placing a profile control gel into a formation having varying zones of permeability comprising:

• (a) injecting a solidifiable gel containing a gel breaker into a formation which gel enters a zone of greater permeability without use of a mechanical packer thereby blocking a lesser permeability zone as a result of a filter cake build up, where said gel comprises:
• (i) water;
• (ii) about 0.2 to about 5.0 wt. percent of a cross-linkable polymer which is a member selected from the group consisting of polyacrylamide, polyvinyl alcohol, xanthan biopolymers, heteropolysaccharide sodium alginate biopolymers, poly(acrylamide-co-acrylamido-2-methyl-propanesulfonate), a copolymer of N-vinyl-2-pyrrolidone and acrylamide, acrylamide modified polyvinyl alcohol, and mixtures thereof having at least one functional group selected from a member of the group consisting of an amine, an amide, a hydroxyl, or a thiol group;
• and
• (iii) about 0.02 to about 50.0 wt. percent of a partially methylated aminoplast resin which cross-links with said polymer thereby forming a gel of a size and strength sufficient to close pores in a zone of greater permeability in said formation;
• (b) injecting thereafter the gel of step (a) lacking a gel breaker into said higher permeability zone thereby forcing gel containing said gel breaker deeper into the higher permeability zone;
• (c) allowing both gels to solidify in the lesser and higher permeability zones;
• and
• (d) causing the solidified gel containing a gel breaker to liquefy thereby unblocking said lesser permeability zone to fluid flow while said higher permeability zone remains blocked to fluid flow.