Union Oil Company of California

LeRoy W Holm

Donald M Fenton

Paul W Fischer

David S Pye

Dennis L Saunders

George G Bernard

Donald H Ferr

Robert C Ransom

The permeability of higher permeability zones of a subterranean reservoir of heterogeneous permeability is reduced by injecting an aqueous solution of a water soluble surface active agent and then a gas mixture comprising carbon dioxide and a noncondensible, non-hydrocarbon gas insoluble in viscous crude. A stable foam forms in situ useful for blocking escape of solvent fluids into the higher permeability zones of the reservoir during enhanced recovery, typically by carbon dioxide flooding. Preferably, the solution of surface active agent and the gas mixture are injected in alternating slugs to enhance foam formation.

Method for foam emplacement in carbon dioxide enhanced recovery

A method for pollution abatement in groundwaters comprises drilling a series of wells in the path of an advancing front of contaminants in an aquifer, and using the wells to introduce into the aquifer an adsorbent for the particular contaminants present.

Groundwater pollution abatement

An enhanced oil recovery process for subterranean reservoirs wherein there is injected into the reservoir a relatively large slug of a dilute aqueous alkali metal silicate solution. It is optional to follow the silicate solution with an aqueous drive fluid. In treating heterogeneous reservoirs, it is further optional, prior to injecting the large slug of silicate solution, to inject one or more small slugs of the silicate solution alternately with one or more small slugs of a dilute aqueous solution of an agent that reacts with the alkali metal silicate to form a gelatinous precipitate. In the latter instance a small spacer slug of water is injected between successive slugs of the reactant solutions to separate the reactants during injection. It is still another option to precede the injection of the large slug of dilute aqueous alkali metal silicate solution with the injection of a slug of an aqueous solution of an alkali metal or ammonium salt selected from the group consisting of chloride, bromide, iodide and nitrate salts and admixtures thereof.

Enhanced oil recovery using alkaline sodium silicate solutions

A process for recovering oil from a heterogeneous subterranean reservoir having strata of widely varying permeability by injecting therein via a well a slug of a micellar solution followed by an aqeuous drive fluid wherein, at some time prior to the injection to all of the slug of the micellar solution, there is injected into the reservoir one or more aqueous solutions of reagents that react in the reservoir to form a plugging material, one of which reagents contains a polyvalent cation. After the plugging material has formed, the well is produced to remove from the reservoir the unreacted reagent containing a polyvalent cation which polyvalent cation would otherwise react with and reduce the efficiency of the subsequently injected micellar solution.

Micellar flooding process for heterogeneous reservoirs

An enhanced oil recovery process employing an aqueous alkyl polyethylene oxide sulfate solution and a carbon dioxide displacement fluid at injection pressures above about 1,500 p.s.i. The aqueous solution of an alkyl polyethylene oxide sulfate having 8 or 9 carbon atoms in the alkyl group and between 1 and 5 ethoxy groups significantly improves the areal sweep and overall efficiencies of dense fluid carbon dioxide enhanced oil recovery processes, especially under high salinity and low pH conditions. The efficiency of the process is increased as the injection pressure is increased.

Enhanced oil recovery process

A method for determining the fluid saturation, for example the hydrocarbon saturation, the residual oil saturation or water saturation, of a reservoir following a secondary recovery operation wherein there is injected into the reservoir via a well first hydrocarbons and then a secondary recovery medium to return the portion of the reservoir in the immediate vicinity of the well to the same fluid saturation as exists in the bulk of the reservoir. The reservoir is then logged with a logging instrument to determine the hydrocarbon saturation, gas saturation, residual oil and/or water saturation.

Determining residual oil saturation following flooding

A method of conducting an enhanced oil recovery process in a subterranean reservoir wherein, as part of the process, there is injected into the reservoir as a sweep fluid a foam containing carbon dioxide, water and a foaming agent having the formula: ##STR1## wherein R is a straight chain alkyl radical having from 10 to 16 carbon atoms; and M is an alkali metal or ammonium cation, with sodium being preferred. A particularly preferred foaming agent is sodium lauryl sulfoacetate.

Carbon dioxide foam flooding

An enhanced oil recovery process for subterranean reservoirs wherein there is injected into the reservoir a relatively large slug of a dilute aqueous alkali metal silicate solution. It is optional to follow the said silicate solution with an aqueous drive fluid. In treating heterogeneous reservoirs, it is further optional to also inject a small slug of a dilute aqueous solution of an agent that reacts with the alkali metal silicate to form a gelatinous precipitate. In the latter instance a small spacer slug of water is injected between successive slugs of the reactant solutions to separate the reactants during injection.

Oil recovery efficiency of tertiary oil recovery processes using a micellar solution as the displacement fluid is improved by injecting a dilute aqueous solution of an alkali metal silicate into the reservoir subsequent to the micellar solution injection and prior to the drive fluid injection. The alkali metal silicate has a M.sub.2 O/SiO.sub.2 ratio of between 1 and 4.

Micellar flooding process for recovering oil from petroleum reservoirs

A process for the recovery of petroleum from a subterranean formation by the injection of a micellar displacement system consisting of a micellar solution and aqueous phase including the ammonium or alkali metal salt of an aminopolycarboxylic acid as a chelating agent. The chelating agent is present in concentrations in excess of the stoichiometric amount required to chelate the multivalent ion of the aqueous phase.

Micellar flooding process

A soluble oil composition comprised of a liquid hydrocarbon, a preferentially oil-soluble surface active organic sulfonate, a preferentially water-soluble surface active organic sulfonate, and a stabilizing agent. The stabilizing agent can be a monohydric aliphatic alcohol containing 3 to 5 carbon atoms, a polyhydric aliphatic alcohol containing 3 carbon atoms, an aliphatic ketone containing 4 to 6 carbon atoms, a glycol ether containing 4 to 12 carbon atoms, or a dialkylene glycol containing 6 carbon atoms. The composition has particular utility as a displacement fluid in a flooding process for the recovery of oil, and for various well treating applications. The soluble oil composition can be substantially anhydrous, or it can contain water present as a water-in-oil microemulsion.

Soluble oil composition

A soluble oil comprising an admixture of a liquid hydrocarbon, surface active alkyl aryl sulfonates, an organic stabilizing agent, and an alkali metal or ammonium salt of a sulfated alkyl primary alcohol ethoxylate having 12 to 16 carbon atoms in the alkyl group. The preferred ethoxylate is a sulfated surfactant containing an admixture of an alkali metal or ammonium lauryl polyethoxy sulfate having 2 to 6 ethoxy groups and an amide builder. The soluble oil can be substantially anhydrous, or it can contain water present in the form of a water-in-oil microemulsion.

A process for recovering oil from subterranean petroleum reservoirs in which there are successively injected into the reservoir (1) an aqueous alkaline alkali metal silicate solution, (2) a micellar solution, and (3) an aqueous drive fluid; and wherein oil is recovered from one or more production wells spaced apart in the reservoir from the injection well. The micellar solution can be a substantially anhydrous soluble oil, a soluble oil containing water present in the form of a water-in-oil microemulsion, a water-external microemulsion, or an aqueous micellar surfactant solution. Additionally, the micellar solution can be a substantially anhydrous soluble oil or a soluble oil containing water present in the form of a water-in-oil microemulsion followed by a water-external microemulsion.

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Fullerton, CA, United States of America

LeRoy W Holm