Mobil Oil Corporation

Atlantic Richfield Company

Harry L Chang

Evin L Cook

Ralph F Burdyn

James G Kralik

A method for increasing oil recovery from a subterranean formation, the method consisting essentially of injecting a slug of water equal in volume to at least about 20% of the hydrocarbon pore volume of the formation into the formation, thereafter injecting a slug of solvent, the solvent consisting of materials selected from the group consisting of carbon dioxide, nitrogen, methane, hydrocarbons containing from 2 to about 5 carbon atoms and mixtures thereof, into the formation in a volume equal to from about 2% to about 10% of the initial hydrocarbon pore volume of the formation, thereafter injecting a water slug in an volume equal to from about 0.5 to about 3.0 times the volume of the preceding solvent slug, and repeating the solvent and water injection steps for a plurality of cycles with the amount of hydrocarbons containing from 2 to about 5 carbon atoms in the solvent decreasing from about 90 to about 100 mole percent in the initial solvent to about 30 mole percent in the final solvent and with the volume of solvent in each slug after the first being from about 0.5% to about 2.0% of the initial hydrocarbon pore volume of the formation, and injecting after the last solvent slug, a slug of water equal in volume to at least about 20% of the initial hydrocarbon pore volume of the formation.

Method for improving the recovery of oil from a subterranean formation

A process for recovering crude oil from a subterranean formation comprising injecting into the formation a liquid solution consisting essentially of at least one surfactant such as alkyl toluene sulfonate in an aqueous medium and injecting a gas to displace the movable oil effectively toward a production well. The process is advantageous in formations where temperatures preclude effective oil recovery using micellar/polymer chemical floods.

Enhanced oil recovery process with reduced gas drive mobility

Waterflooding employing the use of an initial mobility control slug which is graded at its front end by progressively increasing its viscosity and a terminal mobility control slug which is graded at its back end by progressively decreasing its viscosity. An intermediate mobility control slug of substantially constant viscosity may be injected between the initial and terminal slugs. The invention may be carried out in conjunction with surfactant or alkaline waterflooding.

Oil recovery by waterflooding with improved mobility control

A process for the recovery of oil from a subterranean oil reservoir involving the injection of a microemulsion comprising neutralized organic acids extracted from a petroleum oil, oil, and a co-surfactant having mutual solubility for oil and water. The microemulsion may be injected in two portions with the terminal portion having lower concentrations of oil and co-surfactant than the initial portion. The neutralized organic acids employed in the microemulsion may be produced by the alkaline extraction of a petroleum oil. The microemulsion may also contain an alkyl aryl sulfonate, an alkaline agent, and a monovalent salt.

Oil recovery by microemulsion injection

Recovery of oil from subterranean oil reservoirs by waterflooding employing an alkaline agent and a sulfonate surfactant. An aqueous initiation slug containing an alkaline agent selected from the group consisting of alkali metal and ammonium hydroxides is injected into the reservoir via a suitable injection system. Thereafter an aqueous surfactant slug is injected into the reservoir behind the initiation slug. The surfactant slug contains a sulfonate surfactant and an alkaline agent. Subsequent to injection of the surfactant slug, an aqueous flooding medium is injected in order to displace the oil within the reservoir to a production system from which it is recovered. A portion of the flooding medium may contain a thickening agent for mobility control purposes.

Oil recovery by alkaline-surfactant waterflooding

Recovery of oil from a subterranean reservoir employing an alkaline agent-sulfonate surfactant system in conjunction with the injection of a sacrificial system comprising an inorganic polyphosphate and an alkali metal carbonate. An aqueous initiaion slug containing an inorganic polyphosphate, an alkali metal carbonate and an alkaline agent selected from the group consisting of alkali metal and ammonium hydroxides is injected into the reservoir. The initiation slug is followed by the injection of an aqueous surfactant slug which contains an alkaline agent and a sulfonate surfactant. After injection of the surfactant slug, an aqueous flooding medium is injected in order to displace the oil within the reservoir to a production system from which it is recovered. The surfactant slug may also contain an inorganic polyphosphate and alkali metal carbonate and the concentrations of these agents in the surfactant slug may be lower than in the initiation slug.

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Dallas, TX, United States of America

Harry L Chang