Exxon Production Research Company

Walter W Gale

Thomas L Ashcraft

Rhoderick K Saunders

James R Bragg

Clarence W Carpenter

Ronald L Reed

Maura C Puerto

Robert N Healy

Mark P Warchol

To improve the separation of a produced oil-water emulsion containing a surfactant, the emulsion parameters of temperature and salinity are brought within certain critical limits. The emulsion will separate into an injectable brine/surfactant phase and a pipeline quality crude oil phase. The operable salinity range is from about 70% to about 130% of the reservoir salinity, and the operable temperature range is from about 75.degree. F. lower to about 75.degree. F. higher than the temperature of the reservoir from which the emulsion was produced.

Method for treating oil-water emulsions and recovering surfactants

To reduce the surfactant adsorption in a subterranean formation during a surfactant or microemulsion flooding process, lignosulfonate salts are injected into the formation after the surfactant solution has already been injected. The lignosulfonate afterflush may contain a thickener to promote better sweep efficiency, and water or brine will usually be used to drive the lignosulfonate salts through the reservoir to a production well.

Enhanced oil recovery process utilizing a lignosulfonate as a

A method for recovering oil from a subterranean formation is disclosed wherein a novel solution is injected into and driven through the formation. The solution contains an effective amount of surface-active agent having the general formula

Propoxylated ethoxylated surfactants and method of recovering oil

To improve the sweep efficiency of a microemulsion flooding process to recover crude oil from a subterranean formation, a mobility control polymer is added to the microemulsion to increase its viscosity. To enable the compatible incorporation of the polymer and surfactant into the microemulsion, while still utilizing an aqueous component having a salinity near that of the formation, a microemulsion oil component is used for which the surfactant's optimal salinity is substantially higher than for reservoir crude oil.

Microemulsions which compatibly incorporate viscosifiers and their use

Crude oil remaining in a subterranean formation is recovered through the injection of a microemulsion comprising an oil, i.e. a refined or crude oil, an aqueous medium and as a surfactant, a C.sub.8-16 orthoxylene sulfonate. The aqueous medium is preferably a brine having a salt concentration of up to about 2 1/2% by weight, although increased brine tolerance can be achieved by inclusion of a cosurfactant within the microemulsion. When utilized in the secondary or tertiary recovery of crude oil, the microemulsion is preferably followed by thickened water and thereafter unthickened water injected into and through the subterranean formation.

Microemulsion flooding process

A water-external microemulsion and a method of recovering crude oil therewith, the water-external microemulsion being one which comprises at least 90% by weight of an aqueous medium, an oil component and a surfactant comprising a C.sub.8-16 orthoxylene sulfonate in an amount greater than the critical micelle concentration to form the microemulsion. The water-external microemulsion allows for effective and efficient crude oil recovery by providing minimum adsorption and low oil-water interfacial tension.

Water-external microemulsion and method of recovering oil therewith

A method is disclosed for recovering oil from a subterranean oil-bearing formation wherein a liquid solution in injected into and driven through the formation and oil is recovered from the formation. The liquid solution contains an effective amount of a surface-active agent having the general formula: ##EQU1## or ##EQU2## wherein R.sub.1 is a benzene, toluene, or xylene radical having a linear or branched alkyl substituent containing from 6 to 24 carbon atoms;

Oil recovery method using a surfactant

One embodiment includes an oil recovery process, more particularly a secondary or tertiary type crude oil recovery process utilizing a drive fluid to move a displacing fluid through a subterranean formation wherein the displacing fluid displaces crude oil therefrom and is driven through the formation by means of the drive fluid. The crude oil recovery process is improved by utilizing as the drive fluid a thickened, transparent, aqueous solution of a water-soluble sulfated, polyethoxylated C.sub.10 -C.sub.18 primary alcohol or alkylated phenol. The displacing fluid is generally an aqueous surfactant solution, a miscible displacing medium or most preferably a microemulsion. In a further embodiment, the water-soluble, polyethoxylated C.sub.10 -C.sub.18 primary alcohol or alkylated phenol is employed as a mobility control agent in a waterflood thereby increasing the sweep efficiency thereof.

Growing community of inventors

Houston, TX, United States of America

Walter W Gale