Abstract: A profile control method for closing off a more permeable zone of a formation where water, high fluid flow, or high perssures are encountered. A water-external emulsion containing a monomer, a cross-linker, free radical initiators and reaction inhibitors is injected into the formation. There they react to form plastic-like solid spheres in the more permeable formation zone. Because the spheres are not water soluble and have high compressive strength, they can be used in severe flow applications. Ethylene, propylene and styrene monomers can be utilized to form solid spheres of polyethylene, polypropylene or polystyrene.

Abstract: A method for minimizing blockage in a zone of lesser permeability when injecting gels into a formation during profile control. A solidifiable gel which comprises a hydroxyproyl guar gum containing a gel breaker is injected into the formation where it enters a zone of lesser and a zone of greater permeability. Said gel blocks pores in the zone of lesser permeability. A second solidifiable gel formed from a melamine formaldehyde resin, a crosslinkable polymer, and lacking a gel breaker is injected into the zone of greater permeability where it subsequently solidifies. Said gel contained in the zone of lesser permeability liquefies thereby unblocking this zone. Afterwards, a water-flooding enhanced oil recovery method is directed into the zone of lesser permeability.

Abstract: A method for minimizing blockage in a zone of lesser permeability when injecting gels into a formation during profile control. A solidifiable gel containing a gel breaker is injected into the formation where it enters a zone of lesser and a zone of greater permeability. Said gel blocks pores in the zone of lesser permeability. Another solidifiable gel lacking a gel breaker is injected into the zone of greater permeability where it subsequently solidifies. Said gel contained in the zone of lesser permeability liquefies thereby unblocking this zone. Afterwards, a water-flooding enhanced oil recovery method is directed into the zone of lesser permeability.

Abstract: Relatively high permeability zones in a subterranean formation vertically bounded by relatively low permeability zones are selectively plugged by first injecting a solidifiable selective gel solution, preferably a xanthan/chromium gel solution, at a pressure sufficient to cause the gel solution to coat and temporarily plug the injection face of the low permeability zones without any significant amount of the gel penetrating the low permeability zones while allowing the gel solution to flow into the relatively high permeability zones. Reasonably promptly thereafter and before the selective gel solution solidifies in the high permeability zones, a solidifiable non-selective solution is injected into the formation that preferentially enters the relatively high permeability zones and allowed to solidify and plug the relatively high permeability zones.