Abstract: Enhanced (WAG type) oil recovery process in an underground reservoir uses forced injection, through one or more wells, alternately of fluid slugs and gas slugs, and recovery, through one or more production wells, of petroleum fluids displaced by the wetting fluid and the gas injected. The process includes dissolving a pressurized gas in the liquid of certain slugs and, after injection, relieving the pressure prevailing in the reservoir so as to generate gas bubbles by nucleation in the smallest pores, which has the effect of driving the oil away from the less permeable zones into the more permeable zones (with large pores or with fractures) where the oil is swept by the gas slugs injected later on. Implementation of the process considerably increases the oil recovery ratio that is usually reached with WAG type processes.

Abstract: The invention is used to manufacture an inhomogeneous medium whose porosity and permeability undergo rapid transitions from one point to another of its volume, by juxtaposing different materials without creating a barrier. Such a transition is made by juxtaposing a first material and a second material with a different porosity to the first. One of them can be a rock sample such as sandstone for example, the other can be a composite material obtained by agglomerating pyrex powder for example, the whole being heated according to a specific temperature cycle up to a temperature (TR) lower than the melting point of the two materials but sufficient to achieve partial melting of one of the materials at the interface with the other material, but without formation of a continuous or discontinuous capillary barrier between them, or an interzone with preferred passage for fluids. Thus, different composite materials can be juxtaposed to constitute the inhomogeneous medium.

Abstract: Modelling method for optimizing faster and more realistically the displacement conditions, in a porous medium wettable by a first fluid (water for example), of a mixture of fluids including this wetting fluid and at least another fluid (oil and possibly gas).

Abstract: The method according to the invention is aimed at increasing the efficiency of the conventional enhanced petroleum fluid (O) recovery method (WAG) in an underground reservoir, according to which displacement is achieved towards production wells by means of alternate injections of water slugs (W) and of gas slugs (G) into one or more injection wells. It is characterized in that a substance (alcohol for example) allowing the spreading coefficient (S) to be made negative is added to one or more water slugs. The proportion to be added is selected as a function of the pressure and temperature conditions of the reservoir to be swept. The petroleum fluid to be displaced is distributed in the form of meniscuses that reduce the mobility of the gas and improve the sweep capacity thereof. The method allows to better control the input profile, and a greater and therefore more efficient injection pressure can be used. The method can be used in the field of enhanced oil recovery.

Abstract: A process for the enhanced oil recovery in oil reservoirs having a significant cation exchange capacity. A displacement slug is injected into an injection well formed from several successive zones, the solubility in the injection water of the anionic surfactant which it contains being adjusted so as to increase, for compensating the rock-micellar solution interactions, from one zone of the slug to the next considering the order of introducing the different zones of the slug.

Abstract: Process for reducing or suppressing water penetration into oil or gas producing wells which comprises injecting an aqueous polymer solution of controlled viscosity into an underground formation and then placing the well on production. The polymer is, for example, hydrolyzed polyacrylamide and the solution is preferably a salt solution.