Process for the reduction of the relative permeability to water in oil-bearing formations

• Main Authors: Barbosa, Luiz Cesar Ferreira, Coelho, Sérgio Luiz Pereira De Freitas, De Holleben, Carlos Roberto Carvalho, De Godoy, Geraldo Maria Ramos
• Format: Patent
• Language: English
• Published: 05.11.2002

The present invention relates to a process for the selective and controlled reduction of the relative permeability to water in oil-bearing formations, and more specifically to such a process whereby said reduction is achieved with the aid of successive polymer slugs, which are adsorbed to the rock surface and among themselves, creating a hydrophilic film which swells in the presence of water and strongly reduces the permeability to water. On the contrary, in the presence of oil the film keeps its original thickness, so that the permeability to oil is only slightly reduced. A process for the selective and controlled reduction of permeability to water in oil-bearing formations made up of sandstone or limestone, the process comprising the injection of a slug of polymer aqueous solutions having a polarity opposite to the polarity of the rock, followed by the injection of a spacing slug of alkaline halide and then a fresh slug of polymer aqueous solution, the polarity of which is opposite to the polarity of the first polymer slug, and then a slug of aqueous solution of trivalent metal crosslinking agent to effect the partial crosslinking of the polymer charges, the polymer layers being successively added until the injection pressure of the polymer aqueous solutions show that the desired Residual Resistance Factor RRF was attained, and well production may be resumed.